How to build a Makeblock Bluetooth/WiFi Cellbot car

November 22, 2014 by Aaron

Ingredients:
– LG Optimus Dynamic
– PC game controller (joystick)
– pygame for joystick input
– python script runs on PC to translate joystick input to movement commands
– SL4A to send movement commands from PC to smartphone over WiFi
– smartphone sends movement commands to Arduino via Bluetooth (also SL4A)
– Arduino translates commands to movement

First, we taught Bao to listen with Bluetooth

That was using pyserial, connecting directly from PC to Arduino via COM17.

I used that to build a basic instruction set to control movement. E.g.,:
!fwd 10
!bwd 5
!left 3
!right 10
!fwdleft 10 5
!bwdright 6 6
!stop

Those instructions are parsed and executed on the Arduino. The numbers tell how much the joystick was deflected.

But it wasn’t very interesting to connect directly from PC to robot via Bluetooth. I wanted to strap my smartphone on to add that extra layer of sensors and computing power. So my scheme was for my PC to talk to my smartphone and for the smartphone to be like the Jewel Wasp, controlling the robot via Bluetooth.

This was the main Python code running on my PC:


#!/usr/bin/env python

import android
import serial
import pygame
import sys

def initAndroid():
  # LG dynamic
  global g_droid
  global g_bao

  uuid = "00001101-0000-1000-8000-00805F9B34FB"
  mac = "98:D3:31:B0:E9:37" # makeblock mac
  g_droid = android.Android(('192.168.1.3', 33333))
  g_droid.wakeLockAcquirePartial()
  g_droid.bluetoothConnect(uuid, mac)
  conns = g_droid.bluetoothActiveConnections()
  if not conns.result:
     print "Android phone failed to link to robo's Bluetooth"
     sys.exit(0)
  else:
    print "Bluetooth connected"
  g_bao = conns.result.keys()[0]
  g_droid.bluetoothWrite("!beep\n", g_bao)

g_bao = None
g_droid = None
#g_bao = serial.Serial("COM17", 9600) # laptop bluetooth
initAndroid()

g_joyFwdBwdPos = 0
g_joyLeftRightPos = 0

# allow multiple joysticks
joy = []

def cleanupAndroid():
  global g_droid 
  global g_bao

  if g_droid:
    g_droid.bluetoothStop(g_bao)
    g_droid.wakeLockRelease()

# handle joystick event
def handleJoyEvent(e):
    global g_joyFwdBwdPos
    global g_joyLeftRightPos

    if e.type == pygame.JOYAXISMOTION:
        axis = "unknown"
        if (e.dict['axis'] == 1):
            axis = "X"

        if (e.dict['axis'] == 0):
            axis = "Y"

        if (e.dict['axis'] == 2):
            axis = "Throttle"

        if (e.dict['axis'] == 3):
            axis = "Z"

        if (axis != "unknown"):
          str = "Axis: %s; Value: %f" % (axis, e.dict['value'])
          # uncomment to debug
          #output(str, e.dict['joy'])

          # Arduino joystick-servo hack

          pos = e.dict['value']
          zero = 0.5

          vector = int(pos * 10)

          # update vectors
          if axis == "X" or axis == "Z":
            if pos < -zero or pos > zero:
              g_joyFwdBwdPos = vector
            else:
              g_joyFwdBwdPos = 0

          if axis == "Y" or axis == "Throttle":
            if pos < -zero or pos > zero:
              g_joyLeftRightPos = vector
            else:
              g_joyLeftRightPos = 0

          # decide move cmd based on vectors
          fbmag = abs(g_joyFwdBwdPos)
          lrmag = abs(g_joyLeftRightPos)
          if g_joyFwdBwdPos < 0:
            if g_joyLeftRightPos < 0:
              roboCmd("!fwdleft %d %d" % (fbmag, lrmag))
            elif g_joyLeftRightPos > 0:
              roboCmd("!fwdright %d %d" % (fbmag, lrmag))
            else:
              roboCmd("!fwd %d" % fbmag) 
          elif g_joyFwdBwdPos > 0:
            if g_joyLeftRightPos < 0:
              roboCmd("!bwdleft %d %d" % (fbmag, lrmag))
            elif g_joyLeftRightPos > 0:
              roboCmd("!bwdright %d %d" % (fbmag, lrmag))
            else:
              roboCmd("!bwd %d" % fbmag)
          elif g_joyLeftRightPos  < 0:
            roboCmd("!left %d" % lrmag)
          elif g_joyLeftRightPos > 0:
            roboCmd("!right %d" % lrmag)
          else:
            roboCmd("!stop")

    elif e.type == pygame.JOYBUTTONDOWN:
        str = "Button: %d" % (e.dict['button'])
        # uncomment to debug
        output(str, e.dict['joy'])

        button = e.dict['button']

        # Button 0 (trigger) to quit
        if (button == 0):
            print "Bye!\n"
            cleanupAndroid()
            quit()
        elif (button == 1):
          roboCmd("!beep")
    else:
        pass

# print the joystick position
def output(line, stick):
    print "Joystick: %d; %s" % (stick, line)

# wait for joystick input
def joystickControl():
    while True:
        e = pygame.event.wait()
        if (e.type == pygame.JOYAXISMOTION or e.type == pygame.JOYBUTTONDOWN):
            handleJoyEvent(e)

g_lastRoboCmd = None
def roboCmd(roboCmd):
  global g_lastRoboCmd
  global g_bao

  if "fwd" in roboCmd or "bwd" in roboCmd \
    or "left" in roboCmd or "right" in roboCmd \
    or "stop" in roboCmd:
    # don't send redundant movement commands to save data
    if g_lastRoboCmd == roboCmd:
      return

  g_lastRoboCmd = roboCmd
  print roboCmd

  if g_droid:
    g_droid.bluetoothWrite(roboCmd + "\n", g_bao)
  else:
    g_bao.write(roboCmd + "\n")

# main method
def main():
    # initialize pygame
    pygame.joystick.init()
    pygame.display.init()
    if not pygame.joystick.get_count():
        print "\nPlease connect a joystick and run again.\n"
        quit()
    print "\n%d joystick(s) detected." % pygame.joystick.get_count()
    for i in range(pygame.joystick.get_count()):
        myjoy = pygame.joystick.Joystick(i)
        myjoy.init()
        joy.append(myjoy)
        print "Joystick %d: " % (i) + joy[i].get_name()
    print "Depress trigger (button 0) to quit.\n"

    # run joystick listener loop
    joystickControl()

# allow use as a module or standalone script
if __name__ == "__main__":
    main()

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#!/usr/bin/env python

import android

import serial

import pygame

import sys

def initAndroid():

# LG dynamic

global g_droid

global g_bao

uuid = "00001101-0000-1000-8000-00805F9B34FB"

mac = "98:D3:31:B0:E9:37" # makeblock mac

g_droid = android.Android(('192.168.1.3', 33333))

g_droid.wakeLockAcquirePartial()

g_droid.bluetoothConnect(uuid, mac)

conns = g_droid.bluetoothActiveConnections()

if not conns.result:

print "Android phone failed to link to robo's Bluetooth"

sys.exit(0)

else:

print "Bluetooth connected"

g_bao = conns.result.keys()[0]

g_droid.bluetoothWrite("!beep\n", g_bao)

g_bao = None

g_droid = None

#g_bao = serial.Serial("COM17", 9600) # laptop bluetooth

initAndroid()

g_joyFwdBwdPos = 0

g_joyLeftRightPos = 0

# allow multiple joysticks

joy = []

def cleanupAndroid():

global g_droid

global g_bao

if g_droid:

g_droid.bluetoothStop(g_bao)

g_droid.wakeLockRelease()

# handle joystick event

def handleJoyEvent(e):

global g_joyFwdBwdPos

global g_joyLeftRightPos

if e.type == pygame.JOYAXISMOTION:

axis = "unknown"

if (e.dict['axis'] == 1):

axis = "X"

if (e.dict['axis'] == 0):

axis = "Y"

if (e.dict['axis'] == 2):

axis = "Throttle"

if (e.dict['axis'] == 3):

axis = "Z"

if (axis != "unknown"):

str = "Axis: %s; Value: %f" % (axis, e.dict['value'])

# uncomment to debug

#output(str, e.dict['joy'])

# Arduino joystick-servo hack

pos = e.dict['value']

zero = 0.5

vector = int(pos * 10)

# update vectors

if axis == "X" or axis == "Z":

if pos < -zero or pos > zero:

g_joyFwdBwdPos = vector

else:

g_joyFwdBwdPos = 0

if axis == "Y" or axis == "Throttle":

if pos < -zero or pos > zero:

g_joyLeftRightPos = vector

else:

g_joyLeftRightPos = 0

# decide move cmd based on vectors

fbmag = abs(g_joyFwdBwdPos)

lrmag = abs(g_joyLeftRightPos)

if g_joyFwdBwdPos < 0:

if g_joyLeftRightPos < 0:

roboCmd("!fwdleft %d %d" % (fbmag, lrmag))

elif g_joyLeftRightPos > 0:

roboCmd("!fwdright %d %d" % (fbmag, lrmag))

else:

roboCmd("!fwd %d" % fbmag)

elif g_joyFwdBwdPos > 0:

if g_joyLeftRightPos < 0:

roboCmd("!bwdleft %d %d" % (fbmag, lrmag))

elif g_joyLeftRightPos > 0:

roboCmd("!bwdright %d %d" % (fbmag, lrmag))

else:

roboCmd("!bwd %d" % fbmag)

elif g_joyLeftRightPos < 0:

roboCmd("!left %d" % lrmag)

elif g_joyLeftRightPos > 0:

roboCmd("!right %d" % lrmag)

else:

roboCmd("!stop")

elif e.type == pygame.JOYBUTTONDOWN:

str = "Button: %d" % (e.dict['button'])

# uncomment to debug

output(str, e.dict['joy'])

button = e.dict['button']

# Button 0 (trigger) to quit

if (button == 0):

print "Bye!\n"

cleanupAndroid()

quit()

elif (button == 1):

roboCmd("!beep")

else:

pass

# print the joystick position

def output(line, stick):

print "Joystick: %d; %s" % (stick, line)

# wait for joystick input

def joystickControl():

while True:

e = pygame.event.wait()

if (e.type == pygame.JOYAXISMOTION or e.type == pygame.JOYBUTTONDOWN):

handleJoyEvent(e)

g_lastRoboCmd = None

def roboCmd(roboCmd):

global g_lastRoboCmd

global g_bao

if "fwd" in roboCmd or "bwd" in roboCmd \

or "left" in roboCmd or "right" in roboCmd \

or "stop" in roboCmd:

# don't send redundant movement commands to save data

if g_lastRoboCmd == roboCmd:

return

g_lastRoboCmd = roboCmd

print roboCmd

if g_droid:

g_droid.bluetoothWrite(roboCmd + "\n", g_bao)

else:

g_bao.write(roboCmd + "\n")

# main method

def main():

# initialize pygame

pygame.joystick.init()

pygame.display.init()

if not pygame.joystick.get_count():

print "\nPlease connect a joystick and run again.\n"

quit()

print "\n%d joystick(s) detected." % pygame.joystick.get_count()

for i in range(pygame.joystick.get_count()):

myjoy = pygame.joystick.Joystick(i)

myjoy.init()

joy.append(myjoy)

print "Joystick %d: " % (i) + joy[i].get_name()

print "Depress trigger (button 0) to quit.\n"

# run joystick listener loop

joystickControl()

# allow use as a module or standalone script

if __name__ == "__main__":

main()

And this was what I had on the Arduino:



		
		
			
			

			
			#include <Makeblock.h>
#include <Arduino.h>
#include <String.h>
#include <SoftwareSerial.h>
#include <Wire.h>

MeDCMotor MotorL(M1);  
MeDCMotor MotorR(M2);
MeUltrasonicSensor ultrasonic(PORT_3);

MeBluetooth bluetooth(PORT_5);

const int MAXBUFSZ = 128;
char g_lineBuf[MAXBUFSZ]; 
int g_bufReadIdx = 0;

// movement settings
const boolean g_debug = true;
const int g_stepPeriod = 50;
const int g_maxStepsForward = 3000 / g_stepPeriod;
const int g_maxTurnSteps = 3000 / g_stepPeriod;
const int g_minSpeed = 45;
const int g_maxSpeed = 255;
const int g_speedFactor = 23;
const float g_leftTrim = .97;
const float g_rightTrim = 1.;

// enums
const int LED_PIN = 13;
const int EBRAKE_STOP = 2; // full stop
const int EBRAKE_WAIT = 1; // wait for "Go" signal
const int EBRAKE_GO = 0; // brakes off and GO!
const int MODE_ULTRASONIC = 0;
const int MODE_REMOTE = 1;
const int ULTRASONIC_INIT_SPEED = 200;

// robo state machine
int g_moveSpeed = ULTRASONIC_INIT_SPEED;
int g_numStepsForward = 0;
int g_numTurnSteps = 0;
boolean g_rightFlag;
int g_ebrake = EBRAKE_STOP;
long g_timeLastBlocked = 0;
uint8_t g_mode = MODE_REMOTE;

void setup()
{
  Serial.begin(9600);
  Serial.println("Software serial on");

  bluetooth.begin(9600);
  Serial.println("Bluetooth on");

  g_lineBuf[0] = '\0';
  ResetUltrasonic(EBRAKE_STOP);
  pinMode(LED_PIN, OUTPUT); // "obstructed" LED

  Serial.println("Bao ready");
}

void loop()
{
  char inDat;
  boolean hasBlue = false;

  hasBlue = bluetooth.available();

  if (hasBlue)
  {
    ResetUltrasonic(EBRAKE_GO);
    inDat = bluetooth.read();
    Serial.print(inDat);

    readIntoLineBuf(inDat);
    if (cmdLineReady())
    {
      String cmd(g_lineBuf);
      if (g_debug)
        Serial.println("COMMAND " + cmd);
      processCommand(cmd);
    }
  }
  else if (g_mode != MODE_REMOTE
    && millis() % g_stepPeriod == 0)
    doUltrasonicCar();
}

bool processCommand(String cmd)
{
  if (cmd == "!beep")
  {
    buzzerOn();
    delay(100);
    buzzerOff();
  }
  else if (cmd.startsWith("!fwd "))
    Forward(getSpeed(cmd, 0));
  else if (cmd.startsWith("!bwd "))
    Backward(getSpeed(cmd, 0));
  else if (cmd.startsWith("!left "))
    TurnLeft(getSpeed(cmd, 0));
  else if (cmd.startsWith("!right "))
    TurnRight(getSpeed(cmd, 0));
  else if (cmd.startsWith("!fwdleft"))
    ForwardAndLeft(getSpeed(cmd, 0), getSpeed(cmd, 1));
  else if (cmd.startsWith("!fwdright"))
    ForwardAndRight(getSpeed(cmd, 0), getSpeed(cmd, 1));
  else if (cmd.startsWith("!bwdleft"))
    BackwardAndTurnLeft(getSpeed(cmd, 0), getSpeed(cmd, 1));
  else if (cmd.startsWith("!bwdright"))
    BackwardAndTurnRight(getSpeed(cmd, 0), getSpeed(cmd, 1));
  else
    Stop();
}

int getSpeed(String cmd, int idx)
{
  int mag = getCmdInt(cmd, idx);
  return g_speedFactor * mag + g_minSpeed;
}

int getCmdInt(String cmd, int idx)
{
  int spaceIdx = cmd.indexOf(' ');
  for (int i=0; i < idx; i++)
    spaceIdx = cmd.indexOf(' ', spaceIdx+1);

  return cmd.substring(spaceIdx+1).toInt();
}

bool cmdLineReady()
{
  if (g_bufReadIdx != 0)
    return false; // still building line

  if (g_lineBuf[0] != '!')
    return false; // not a command line

  return true;
}

void readIntoLineBuf(char c)
{
  if (c == '\n' || c == '\r' || c == '\0')
  {
    // finish line for processing, set ready for next line
    g_bufReadIdx = 0;
    return;
  }

  if (g_bufReadIdx >= MAXBUFSZ - 1)
  {
    // drop overflow bytes
    return;
  }

  g_lineBuf[g_bufReadIdx] = c;
  g_lineBuf[g_bufReadIdx+1] = '\0';
  g_bufReadIdx++;
}

void doUltrasonicCar()
{
  int distance = ultrasonic.distanceCm();
  
  boolean isBlocked = (distance > 0 && distance < 60);
  if (isBlocked)
    g_timeLastBlocked = millis();
  else if (millis() - g_timeLastBlocked < 100)
    isBlocked = true;

  if (isBlocked)
    digitalWrite(LED_PIN, HIGH);
  else
    digitalWrite(LED_PIN, LOW);

  boolean isStuck 
    = (g_numTurnSteps > g_maxTurnSteps
      || g_numStepsForward > g_maxStepsForward);

  if (g_ebrake == EBRAKE_STOP && !isBlocked)
  {
    // /unstuck, ready for go signal
    g_ebrake = EBRAKE_WAIT; 
    return;
  }
  else if (g_ebrake == EBRAKE_WAIT && isBlocked)
  {
    // "Go!"
    ResetUltrasonic(EBRAKE_GO);
    return;
  }
  else if (g_ebrake == EBRAKE_GO && isStuck)
  {
    // stuck -- yank ebrake
    g_ebrake = EBRAKE_STOP;
    Stop();
    return;
  }

  if (g_ebrake != EBRAKE_GO)
  {
    // halt until !blocked and receive "Go" signal
    return;
  }
  
  if (isBlocked)
  {
    // evasive maneuvers!
    randomSeed(analogRead(A4));
    int randnum = random(300);

    if (distance > 30)
    {
      if (randnum > 150 && !g_rightFlag)
        TurnLeft(g_moveSpeed);   
      else
        TurnRight(g_moveSpeed);  
    }
    else
    {
      if (randnum > 150) 
        BackwardAndTurnLeft(g_moveSpeed, g_moveSpeed);
      else 
        BackwardAndTurnRight(g_moveSpeed, g_moveSpeed);
    }
  }
  else
  {
    // ONWARD!
    Forward(g_moveSpeed);
  }
}

void ResetUltrasonic(int brakePos)
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps = 0;
  g_ebrake = brakePos;
  
  if (g_debug && g_mode == MODE_ULTRASONIC)
    Serial.println("Reset");
}

void Stop()
{
  MotorL.stop();
  MotorR.stop();
}

void Forward(int speed)
{
  g_numStepsForward++;
  g_numTurnSteps = 0;
  g_rightFlag = false;

  MotorL.run(speed * g_leftTrim);
  MotorR.run(speed * g_rightTrim);
  
  if (g_debug)
    Serial.println("Forward");
}

void ForwardAndLeft(int fspeed, int lspeed)
{
  g_numStepsForward++;
  g_numTurnSteps++;
  g_rightFlag = false;

  MotorL.run(fspeed - (lspeed / 2));
  MotorR.run(fspeed);
  
  if (g_debug)
    Serial.println("Forward+Left");
}

void ForwardAndRight(int fspeed, int rspeed)
{
  g_numStepsForward++;
  g_numTurnSteps++;
  g_rightFlag = true;

  MotorL.run(fspeed);
  MotorR.run(fspeed - (rspeed / 2));
  
  if (g_debug)
    Serial.println("Forward+Right");
}

void Backward(int speed)
{
  g_rightFlag = false;
  g_numTurnSteps = 0;
  MotorL.run(-speed);
  MotorR.run(-speed);

  if (g_debug)
    Serial.println("Backward");
}

void TurnLeft(int speed)
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps++;

  MotorL.run(-speed / 2);
  MotorR.run(speed / 2);
  
  if (g_debug)
    Serial.println("Left");
}

void TurnRight(int speed)
{
  g_rightFlag = true;
  g_numStepsForward = 0;
  g_numTurnSteps++;

  MotorL.run(speed / 2);
  MotorR.run(-speed / 2);
  
  if (g_debug)
    Serial.println("Right");
}

void BackwardAndTurnLeft(int bspeed, int lspeed)
{
  g_rightFlag = true;
  g_numStepsForward = 0;
  g_numTurnSteps++;

  MotorL.run(-bspeed + (lspeed / 2));
  MotorR.run(-bspeed);

  if (g_debug)
    Serial.println("Backward+Left");
}

void BackwardAndTurnRight(int bspeed, int rspeed)
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps++;

  MotorL.run(-bspeed);
  MotorR.run(-bspeed + (rspeed / 2));

  if (g_debug)
    Serial.println("Backward+Right");
}

void ChangeSpeed(int spd)
{
  g_moveSpeed = spd;
}
			
				
					
				
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						#include <Makeblock.h>
#include <Arduino.h>
#include <String.h>
#include <SoftwareSerial.h>
#include <Wire.h>
 
MeDCMotor MotorL(M1);  
MeDCMotor MotorR(M2);
MeUltrasonicSensor ultrasonic(PORT_3);
 
MeBluetooth bluetooth(PORT_5);
 
const int MAXBUFSZ = 128;
char g_lineBuf[MAXBUFSZ]; 
int g_bufReadIdx = 0;
 
// movement settings
const boolean g_debug = true;
const int g_stepPeriod = 50;
const int g_maxStepsForward = 3000 / g_stepPeriod;
const int g_maxTurnSteps = 3000 / g_stepPeriod;
const int g_minSpeed = 45;
const int g_maxSpeed = 255;
const int g_speedFactor = 23;
const float g_leftTrim = .97;
const float g_rightTrim = 1.;
 
// enums
const int LED_PIN = 13;
const int EBRAKE_STOP = 2; // full stop
const int EBRAKE_WAIT = 1; // wait for "Go" signal
const int EBRAKE_GO = 0; // brakes off and GO!
const int MODE_ULTRASONIC = 0;
const int MODE_REMOTE = 1;
const int ULTRASONIC_INIT_SPEED = 200;
 
// robo state machine
int g_moveSpeed = ULTRASONIC_INIT_SPEED;
int g_numStepsForward = 0;
int g_numTurnSteps = 0;
boolean g_rightFlag;
int g_ebrake = EBRAKE_STOP;
long g_timeLastBlocked = 0;
uint8_t g_mode = MODE_REMOTE;
 
void setup()
{
  Serial.begin(9600);
  Serial.println("Software serial on");
 
  bluetooth.begin(9600);
  Serial.println("Bluetooth on");
 
  g_lineBuf[0] = '\0';
  ResetUltrasonic(EBRAKE_STOP);
  pinMode(LED_PIN, OUTPUT); // "obstructed" LED
 
  Serial.println("Bao ready");
}
 
void loop()
{
  char inDat;
  boolean hasBlue = false;
 
  hasBlue = bluetooth.available();
 
  if (hasBlue)
  {
    ResetUltrasonic(EBRAKE_GO);
    inDat = bluetooth.read();
    Serial.print(inDat);
 
    readIntoLineBuf(inDat);
    if (cmdLineReady())
    {
      String cmd(g_lineBuf);
      if (g_debug)
        Serial.println("COMMAND " + cmd);
      processCommand(cmd);
    }
  }
  else if (g_mode != MODE_REMOTE
    && millis() % g_stepPeriod == 0)
    doUltrasonicCar();
}
 
bool processCommand(String cmd)
{
  if (cmd == "!beep")
  {
    buzzerOn();
    delay(100);
    buzzerOff();
  }
  else if (cmd.startsWith("!fwd "))
    Forward(getSpeed(cmd, 0));
  else if (cmd.startsWith("!bwd "))
    Backward(getSpeed(cmd, 0));
  else if (cmd.startsWith("!left "))
    TurnLeft(getSpeed(cmd, 0));
  else if (cmd.startsWith("!right "))
    TurnRight(getSpeed(cmd, 0));
  else if (cmd.startsWith("!fwdleft"))
    ForwardAndLeft(getSpeed(cmd, 0), getSpeed(cmd, 1));
  else if (cmd.startsWith("!fwdright"))
    ForwardAndRight(getSpeed(cmd, 0), getSpeed(cmd, 1));
  else if (cmd.startsWith("!bwdleft"))
    BackwardAndTurnLeft(getSpeed(cmd, 0), getSpeed(cmd, 1));
  else if (cmd.startsWith("!bwdright"))
    BackwardAndTurnRight(getSpeed(cmd, 0), getSpeed(cmd, 1));
  else
    Stop();
}
 
int getSpeed(String cmd, int idx)
{
  int mag = getCmdInt(cmd, idx);
  return g_speedFactor * mag + g_minSpeed;
}
 
int getCmdInt(String cmd, int idx)
{
  int spaceIdx = cmd.indexOf(' ');
  for (int i=0; i < idx; i++)
    spaceIdx = cmd.indexOf(' ', spaceIdx+1);
 
  return cmd.substring(spaceIdx+1).toInt();
}
 
bool cmdLineReady()
{
  if (g_bufReadIdx != 0)
    return false; // still building line
 
  if (g_lineBuf[0] != '!')
    return false; // not a command line
 
  return true;
}
 
void readIntoLineBuf(char c)
{
  if (c == '\n' || c == '\r' || c == '\0')
  {
    // finish line for processing, set ready for next line
    g_bufReadIdx = 0;
    return;
  }
 
  if (g_bufReadIdx >= MAXBUFSZ - 1)
  {
    // drop overflow bytes
    return;
  }
 
  g_lineBuf[g_bufReadIdx] = c;
  g_lineBuf[g_bufReadIdx+1] = '\0';
  g_bufReadIdx++;
}
 
void doUltrasonicCar()
{
  int distance = ultrasonic.distanceCm();
  
  boolean isBlocked = (distance > 0 && distance < 60);
  if (isBlocked)
    g_timeLastBlocked = millis();
  else if (millis() - g_timeLastBlocked < 100)
    isBlocked = true;
 
  if (isBlocked)
    digitalWrite(LED_PIN, HIGH);
  else
    digitalWrite(LED_PIN, LOW);
 
  boolean isStuck 
    = (g_numTurnSteps > g_maxTurnSteps
      || g_numStepsForward > g_maxStepsForward);
 
  if (g_ebrake == EBRAKE_STOP && !isBlocked)
  {
    // /unstuck, ready for go signal
    g_ebrake = EBRAKE_WAIT; 
    return;
  }
  else if (g_ebrake == EBRAKE_WAIT && isBlocked)
  {
    // "Go!"
    ResetUltrasonic(EBRAKE_GO);
    return;
  }
  else if (g_ebrake == EBRAKE_GO && isStuck)
  {
    // stuck -- yank ebrake
    g_ebrake = EBRAKE_STOP;
    Stop();
    return;
  }
 
  if (g_ebrake != EBRAKE_GO)
  {
    // halt until !blocked and receive "Go" signal
    return;
  }
  
  if (isBlocked)
  {
    // evasive maneuvers!
    randomSeed(analogRead(A4));
    int randnum = random(300);
 
    if (distance > 30)
    {
      if (randnum > 150 && !g_rightFlag)
        TurnLeft(g_moveSpeed);   
      else
        TurnRight(g_moveSpeed);  
    }
    else
    {
      if (randnum > 150) 
        BackwardAndTurnLeft(g_moveSpeed, g_moveSpeed);
      else 
        BackwardAndTurnRight(g_moveSpeed, g_moveSpeed);
    }
  }
  else
  {
    // ONWARD!
    Forward(g_moveSpeed);
  }
}
 
void ResetUltrasonic(int brakePos)
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps = 0;
  g_ebrake = brakePos;
  
  if (g_debug && g_mode == MODE_ULTRASONIC)
    Serial.println("Reset");
}
 
void Stop()
{
  MotorL.stop();
  MotorR.stop();
}
 
void Forward(int speed)
{
  g_numStepsForward++;
  g_numTurnSteps = 0;
  g_rightFlag = false;
 
  MotorL.run(speed * g_leftTrim);
  MotorR.run(speed * g_rightTrim);
  
  if (g_debug)
    Serial.println("Forward");
}
 
void ForwardAndLeft(int fspeed, int lspeed)
{
  g_numStepsForward++;
  g_numTurnSteps++;
  g_rightFlag = false;
 
  MotorL.run(fspeed - (lspeed / 2));
  MotorR.run(fspeed);
  
  if (g_debug)
    Serial.println("Forward+Left");
}
 
void ForwardAndRight(int fspeed, int rspeed)
{
  g_numStepsForward++;
  g_numTurnSteps++;
  g_rightFlag = true;
 
  MotorL.run(fspeed);
  MotorR.run(fspeed - (rspeed / 2));
  
  if (g_debug)
    Serial.println("Forward+Right");
}
 
void Backward(int speed)
{
  g_rightFlag = false;
  g_numTurnSteps = 0;
  MotorL.run(-speed);
  MotorR.run(-speed);
 
  if (g_debug)
    Serial.println("Backward");
}
 
void TurnLeft(int speed)
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps++;
 
  MotorL.run(-speed / 2);
  MotorR.run(speed / 2);
  
  if (g_debug)
    Serial.println("Left");
}
 
void TurnRight(int speed)
{
  g_rightFlag = true;
  g_numStepsForward = 0;
  g_numTurnSteps++;
 
  MotorL.run(speed / 2);
  MotorR.run(-speed / 2);
  
  if (g_debug)
    Serial.println("Right");
}
 
void BackwardAndTurnLeft(int bspeed, int lspeed)
{
  g_rightFlag = true;
  g_numStepsForward = 0;
  g_numTurnSteps++;
 
  MotorL.run(-bspeed + (lspeed / 2));
  MotorR.run(-bspeed);
 
  if (g_debug)
    Serial.println("Backward+Left");
}
 
void BackwardAndTurnRight(int bspeed, int rspeed)
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps++;
 
  MotorL.run(-bspeed);
  MotorR.run(-bspeed + (rspeed / 2));
 
  if (g_debug)
    Serial.println("Backward+Right");
}
 
void ChangeSpeed(int spd)
{
  g_moveSpeed = spd;
}

The main changes were to handle commands sent via Bluetooth. Bytes were read one at a time and accumulated into a buffer. The buffer was parsed for commands and the commands were executed. I had to tune the vectors a little to take advantage of the analog joystick input and to smooth out transitions to/from any direction.

I rigged the smartphone onto the robot with Legos. Then I downloaded and streamed the robot’s POV using the “IP Webcam” app because why not?

It’s ALIVE! Robot POV

Pilot POV

It worked better than I expected. The controller lag was not too bad, even with the inefficient command string processing scheme.

Tee hee

When I was done playing I restored it back to the old IR + Ultrasonic setup. I still haven’t figured out what’s the best next step from IR to Bluetooth for a kid.

LG Optimus Dynamic – perfect cellbot phone?

November 13, 2014 by Aaron

It is the cheapest, full-featured Android phone that I’ve found. Only $20 on Amazon NEW. It feels like finding hidden treasure because the only reason it’s so cheap is that the phone is targeted for the bottom market. And, normal people who buy the phone later add minutes to use it as a phone. But not us! If everyone did what we want to do with the phone, they’d lose money because there’s no way this package can be produced and sold for a profit at $20. So shhhh… let’s just keep this between you and me.

Here’s what you do after you get it:

(optional) Root it. That link takes you to a super simple one-click script and all you need is a PC and the USB cable that came with the phone. I don’t know why I rooted mine, but it’s Android and you can, so why not? You could install this custom ROM too if you want (I didn’t). And if you screw something up like I did, you always go back to “stock” with this.
Install SL4A — the Scripting Layer for Android. This lets you interface with Android and everything your phone’s hardware allows… from a Python script.
* Install the APK
* Menu > view > interpreters
* Menu > add > Python
* Install the Python APK > OPEN the Python app > Install Python (+ whatever modules you want, like pySerial + pyBluez)
In SL4A, go to Menu > view > interpreters > Menu > start server
(Note the IP address and port, e.g. 192.168.1.3:12345)
From your PC, write a simple Python script called hello.py to talk to the server on your phone:
hello.py

import android droid = android.Android((192.168.1.3, 12345)) droid.ttsSpeak("hello world")

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import android
droid = android.Android((192.168.1.3, 12345))
droid.ttsSpeak("hello world")
Notice the “import android” above. That’s from here. Download android.py and put it next to hello.py above.
python hello.py
CHEER

The hardware isn’t great and it’s still on Gingerbread, but I’m pretty sure it’s still more powerful than NASA’s Lunar Lander. It’s just a steal at $20 for the nice package. Battery life is super and everything works fine. It even has an external micro SD slot! Oh one thing you might want to upgrade for our example above is the Text-to-Speech voice. Gingerbread is old so you don’t get Google’s latest TTS software. So I downloaded IVONA. It’s free, it works for Gingerbread and I like Amy’s UK English voice.

By the way, the SL4A website taught me that I’m not the first brilliant person to think of using smartphones for robots. And, the term for robots that use smartphones is Cellbots. But it still makes me wonder why people still want to mess with things like a $30 XBee WiFi module. Especially when phones like the Optimus Dynamic gives you WiFi (plus everything else) for $20. Who knows.

Happy Hacking!

Robot Kit – Day 7

November 11, 2014 by Aaron

Our new ultrasonic car + IR code seems to work well, even in the living room. You only wanted to switch to MAX SPEED to watch it go nuts:

We made an interesting discovery: mama’s fuzzy bunny slippers are invisible to the ultrasonic sensor. I tried to demonstrate why by bouncing some balls off different surfaces. But I’m not sure if you got it.

PC to android smartphone recipe

November 10, 2014 by Aaron

Bao has been taking a break. I think having a robot that moves on its own stresses you out. You’ve been running to flip the off switch after playing with Bao a little. Maybe it’s too much for a 3 year old to deal with. On the plus side, now you know the deal with batteries and recharging, and how Bao gets slow when he’s low on energy. The “energy” and “battery” concept is handy for explaining why you have to eat and sleep.

Anyway, while Bao has been resting, we’ve moved on to the next phase of Bao’s evolution. After some research, I’ve found the perfect recipe. But first, check out the ingredients to see if you can guess what we’re making:

1) LG Optimus Dynamic
This is a $20 prepaid smartphone. Prepaid meaning you can actually buy minutes to use it as a smartphone (e.g. if you need a spare phone for family visiting from out of town). And this one’s nice because it has “triple minutes” for life. So you can buy 200 minutes and the phone will give you 600 minutes magically. But what I’m really buying this for is the hardware and software. It comes packed with the usual sensors: GPS, accelerometer, compass, light sensor; and communication interfaces: Bluetooth, WiFi, PLUS a camera, video recorder, audio recorder, a 1GHz processor, some RAM and 4GB of storage space, AND whatever apps you want and the Android OS to tie it all together. All for $20! In the robot world, each of these devices would cost $20 or more by themselves. But thanks to the economics of smartphones, you can get them ALL for $20. What a wonderful time we live in. I really feel that smartphone tech will accelerate many more industries. (Example: Oculus Rift.) So instead of buying loosey goosey electronics for your robo, the only thing you need is Bluetooth… to pair with a smartphone.

2) Scripting Layer for Android (SL4A)
This is what you install on your Android phone. SL4A lets you tap into every function on your phone from your favorite scripting language (e.g., Python). SL4A can either run a script stored on the phone, or you can connect to SL4A to run a script from your PC. E.g., check this out:

From your PC:



		
		
			
			

			
			import android
droid = android.Android(('192.168.1.3', 53833))
recog = droid.recognizeSpeech().result
droid.ttsSpeak(recog)

			
				
					
				
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						import android
droid = android.Android(('192.168.1.3', 53833))
recog = droid.recognizeSpeech().result
droid.ttsSpeak(recog)
 
					
				
			
		


This tells your phone at 192.168.1.3 to, "Capture what I say, then say it back to me." How crazy is that? (Browse the API to see what else it can do.) You can tell it to take a picture, make a phone call, or even drive a robot... (hint hint)
3) web2py

This is what I used to make a toddler-proof web interface or "app" or GUI. The front-end (View) is HTML/Javascript, and the backend (Controller) is Python -- perfect for hooking up with SL4A. Right now, it doesn't do much. But it still has you rolling on the floor laughing, because I send the words you type to the phone and the phone says them (using SL4A). You've been having fun typing different words to see how the text-to-speech voice screws it up. Anyway, this bomb-proof custom toddler web UI works much better than VI, which we were using earlier...


Oh, and here's my latest IR + Ultrasonic car code. It's tuned for the 3-wheel car and my kitchen:


		
		
			
			

			
			
#include <Makeblock.h>
#include <SoftwareSerial.h>
#include <Wire.h>

MeDCMotor MotorL(M1);  
MeDCMotor MotorR(M2);
MeUltrasonicSensor UltrasonicSensor(PORT_3);
MeInfraredReceiver infraredReceiverDecode(PORT_6);

const boolean g_debug = true;
const int g_stepPeriod = 50;
const int g_maxStepsForward = 3000 / g_stepPeriod;
const int g_maxTurnSteps = 3000 / g_stepPeriod;
const int g_minSpeed = 45;
const float g_leftTrim = .97;
const float g_rightTrim = 1.;

const int LED_PIN = 13;
const int EBRAKE_STOP = 2; // full stop
const int EBRAKE_WAIT = 1; // wait for "Go" signal
const int EBRAKE_GO = 0; // brakes off and GO!
const int MODE_ULTRASONIC = 0;
const int ULTRASONIC_INIT_SPEED = 150;
const int MODE_IR = 1;

int g_speedFactor = 23;
int g_moveSpeed = ULTRASONIC_INIT_SPEED;
int g_numStepsForward = 0;
int g_numTurnSteps = 0;
boolean g_rightFlag;
int g_ebrake = EBRAKE_STOP;
long g_timeLastBlocked = 0;

uint8_t g_mode = MODE_IR;

void setup()
{
  if (g_debug)
    Serial.begin(9600);

  ResetUltrasonic(EBRAKE_STOP);

  infraredReceiverDecode.begin(); 
  pinMode(LED_PIN, OUTPUT); // "obstructed" LED
}

void loop()
{
  if (infraredReceiverDecode.available() || infraredReceiverDecode.buttonState())
  {
    ResetUltrasonic(EBRAKE_GO);
    switch (infraredReceiverDecode.read())
    {
      case IR_BUTTON_PLUS: 
        Forward();
        break;
      case IR_BUTTON_MINUS:
        Backward();
        break;
      case IR_BUTTON_NEXT:
        TurnRight();
        break;
      case IR_BUTTON_PREVIOUS:
        TurnLeft();
        break;
      case IR_BUTTON_TEST:
        ForwardAndLeft();
        break;
      case IR_BUTTON_RETURN:
        ForwardAndRight();
        break;
      case IR_BUTTON_9:
        ChangeSpeed(g_speedFactor*9+g_minSpeed);
        break;
      case IR_BUTTON_8:
        ChangeSpeed(g_speedFactor*8+g_minSpeed);
        break;
      case IR_BUTTON_7:
        ChangeSpeed(g_speedFactor*7+g_minSpeed);
        break;
      case IR_BUTTON_6:
        ChangeSpeed(g_speedFactor*6+g_minSpeed);
        break;
      case IR_BUTTON_5:
        ChangeSpeed(g_speedFactor*5+g_minSpeed);
        break;
      case IR_BUTTON_4:
        ChangeSpeed(g_speedFactor*4+g_minSpeed);
        break;
      case IR_BUTTON_3:
        ChangeSpeed(g_speedFactor*3+g_minSpeed);
        break;
      case IR_BUTTON_2:
        ChangeSpeed(g_speedFactor*2+g_minSpeed);
        break;
      case IR_BUTTON_1:
        ChangeSpeed(g_speedFactor*1+g_minSpeed);
        break;
      case IR_BUTTON_POWER:
        buzzerOn();
        delay(100);
        buzzerOff();
        break;
      case IR_BUTTON_MENU:
        if (g_mode == MODE_IR)
        {
          buzzerOn();
          delay(100);
          buzzerOff();
          delay(100);
          buzzerOn();
          delay(100);
          buzzerOff();
          delay(100);
          buzzerOn();
          delay(300);
          buzzerOff();

          g_mode = MODE_ULTRASONIC;
          g_moveSpeed = ULTRASONIC_INIT_SPEED;
        }
        else
        {
          buzzerOn();
          delay(100);
          buzzerOff();
          digitalWrite(LED_PIN, LOW);

          g_mode = MODE_IR;
        }

        break;
      default:
        break;
    }
  }
  else
  {
    if (g_mode == MODE_IR)
      Stop();
    else if (millis() % g_stepPeriod == 0)
      doUltrasonicCar();
  }
}

void doUltrasonicCar()
{
  int distance = UltrasonicSensor.distanceCm();
  
  boolean isBlocked = (distance > 0 && distance < 60);
  if (isBlocked)
    g_timeLastBlocked = millis();
  else if (millis() - g_timeLastBlocked < 100)
    isBlocked = true;

  if (isBlocked)
    digitalWrite(LED_PIN, HIGH);
  else
    digitalWrite(LED_PIN, LOW);

  boolean isStuck 
    = (g_numTurnSteps > g_maxTurnSteps
      || g_numStepsForward > g_maxStepsForward);

  if (g_ebrake == EBRAKE_STOP && !isBlocked)
  {
    // /unstuck, ready for go signal
    g_ebrake = EBRAKE_WAIT; 
    return;
  }
  else if (g_ebrake == EBRAKE_WAIT && isBlocked)
  {
    // "Go!"
    ResetUltrasonic(EBRAKE_GO);
    return;
  }
  else if (g_ebrake == EBRAKE_GO && isStuck)
  {
    // stuck -- yank ebrake
    g_ebrake = EBRAKE_STOP;
    Stop();
    return;
  }

  if (g_ebrake != EBRAKE_GO)
  {
    // halt until !blocked and receive "Go" signal
    return;
  }
  
  if (isBlocked)
  {
    // evasive maneuvers!
    randomSeed(analogRead(A4));
    int randnum = random(300);

    if (distance > 30)
    {
      if (randnum > 190 && !g_rightFlag)
        TurnLeft();   
      else
        TurnRight();  
    }
    else
    {
      if (randnum > 190) 
        BackwardAndTurnLeft();
      else 
        BackwardAndTurnRight();
    }
  }
  else
  {
    // ONWARD!
    Forward();
  }
}

void ResetUltrasonic(int brakePos)
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps = 0;
  g_ebrake = brakePos;
  
  if (g_debug && g_mode == 0)
    Serial.println("Reset");
}

void Stop()
{
  MotorL.stop();
  MotorR.stop();
  
  if (g_debug)
    Serial.println("Stop");
}

void Forward()
{
  g_numStepsForward++;
  g_numTurnSteps = 0;
  g_rightFlag = false;

  MotorL.run(g_moveSpeed * g_leftTrim);
  MotorR.run(g_moveSpeed * g_rightTrim);
  
  if (g_debug)
    Serial.println("Forward");
}

void ForwardAndLeft()
{
  g_numStepsForward++;
  g_numTurnSteps++;
  g_rightFlag = false;

  MotorL.run(g_moveSpeed / 2);
  MotorR.run(g_moveSpeed);
  
  if (g_debug)
    Serial.println("Forward+Left");
}

void ForwardAndRight()
{
  g_numStepsForward++;
  g_numTurnSteps++;
  g_rightFlag = true;

  MotorL.run(g_moveSpeed);
  MotorR.run(g_moveSpeed / 2);
  
  if (g_debug)
    Serial.println("Forward+Right");
}

void Backward()
{
  g_rightFlag = false;
  g_numTurnSteps = 0;
  MotorL.run(-g_moveSpeed);
  MotorR.run(-g_moveSpeed);
}
void TurnLeft()
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps++;

  MotorL.run(-g_moveSpeed);
  MotorR.run(g_moveSpeed);
  
  if (g_debug)
    Serial.println("Left");
}
void TurnRight()
{
  g_rightFlag = true;
  g_numStepsForward = 0;
  g_numTurnSteps++;

  MotorL.run(g_moveSpeed);
  MotorR.run(-g_moveSpeed);
  
  if (g_debug)
    Serial.println("Right");
}

void BackwardAndTurnLeft()
{
  g_rightFlag = true;
  g_numStepsForward = 0;
  g_numTurnSteps++;

  MotorL.run(-g_moveSpeed/2);
  MotorR.run(-g_moveSpeed);

  if (g_debug)
    Serial.println("Backward+Left");
}
void BackwardAndTurnRight()
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps++;

  MotorL.run(-g_moveSpeed);
  MotorR.run(-g_moveSpeed/2);

  if (g_debug)
    Serial.println("Backward+Right");
}

void ChangeSpeed(int spd)
{
  g_moveSpeed = spd;
}
			
				
					
				
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#include <Makeblock.h>
#include <SoftwareSerial.h>
#include <Wire.h>
 
MeDCMotor MotorL(M1);  
MeDCMotor MotorR(M2);
MeUltrasonicSensor UltrasonicSensor(PORT_3);
MeInfraredReceiver infraredReceiverDecode(PORT_6);
 
const boolean g_debug = true;
const int g_stepPeriod = 50;
const int g_maxStepsForward = 3000 / g_stepPeriod;
const int g_maxTurnSteps = 3000 / g_stepPeriod;
const int g_minSpeed = 45;
const float g_leftTrim = .97;
const float g_rightTrim = 1.;
 
const int LED_PIN = 13;
const int EBRAKE_STOP = 2; // full stop
const int EBRAKE_WAIT = 1; // wait for "Go" signal
const int EBRAKE_GO = 0; // brakes off and GO!
const int MODE_ULTRASONIC = 0;
const int ULTRASONIC_INIT_SPEED = 150;
const int MODE_IR = 1;
 
int g_speedFactor = 23;
int g_moveSpeed = ULTRASONIC_INIT_SPEED;
int g_numStepsForward = 0;
int g_numTurnSteps = 0;
boolean g_rightFlag;
int g_ebrake = EBRAKE_STOP;
long g_timeLastBlocked = 0;
 
uint8_t g_mode = MODE_IR;
 
void setup()
{
  if (g_debug)
    Serial.begin(9600);
 
  ResetUltrasonic(EBRAKE_STOP);
 
  infraredReceiverDecode.begin(); 
  pinMode(LED_PIN, OUTPUT); // "obstructed" LED
}
 
void loop()
{
  if (infraredReceiverDecode.available() || infraredReceiverDecode.buttonState())
  {
    ResetUltrasonic(EBRAKE_GO);
    switch (infraredReceiverDecode.read())
    {
      case IR_BUTTON_PLUS: 
        Forward();
        break;
      case IR_BUTTON_MINUS:
        Backward();
        break;
      case IR_BUTTON_NEXT:
        TurnRight();
        break;
      case IR_BUTTON_PREVIOUS:
        TurnLeft();
        break;
      case IR_BUTTON_TEST:
        ForwardAndLeft();
        break;
      case IR_BUTTON_RETURN:
        ForwardAndRight();
        break;
      case IR_BUTTON_9:
        ChangeSpeed(g_speedFactor*9+g_minSpeed);
        break;
      case IR_BUTTON_8:
        ChangeSpeed(g_speedFactor*8+g_minSpeed);
        break;
      case IR_BUTTON_7:
        ChangeSpeed(g_speedFactor*7+g_minSpeed);
        break;
      case IR_BUTTON_6:
        ChangeSpeed(g_speedFactor*6+g_minSpeed);
        break;
      case IR_BUTTON_5:
        ChangeSpeed(g_speedFactor*5+g_minSpeed);
        break;
      case IR_BUTTON_4:
        ChangeSpeed(g_speedFactor*4+g_minSpeed);
        break;
      case IR_BUTTON_3:
        ChangeSpeed(g_speedFactor*3+g_minSpeed);
        break;
      case IR_BUTTON_2:
        ChangeSpeed(g_speedFactor*2+g_minSpeed);
        break;
      case IR_BUTTON_1:
        ChangeSpeed(g_speedFactor*1+g_minSpeed);
        break;
      case IR_BUTTON_POWER:
        buzzerOn();
        delay(100);
        buzzerOff();
        break;
      case IR_BUTTON_MENU:
        if (g_mode == MODE_IR)
        {
          buzzerOn();
          delay(100);
          buzzerOff();
          delay(100);
          buzzerOn();
          delay(100);
          buzzerOff();
          delay(100);
          buzzerOn();
          delay(300);
          buzzerOff();
 
          g_mode = MODE_ULTRASONIC;
          g_moveSpeed = ULTRASONIC_INIT_SPEED;
        }
        else
        {
          buzzerOn();
          delay(100);
          buzzerOff();
          digitalWrite(LED_PIN, LOW);
 
          g_mode = MODE_IR;
        }
 
        break;
      default:
        break;
    }
  }
  else
  {
    if (g_mode == MODE_IR)
      Stop();
    else if (millis() % g_stepPeriod == 0)
      doUltrasonicCar();
  }
}
 
void doUltrasonicCar()
{
  int distance = UltrasonicSensor.distanceCm();
  
  boolean isBlocked = (distance > 0 && distance < 60);
  if (isBlocked)
    g_timeLastBlocked = millis();
  else if (millis() - g_timeLastBlocked < 100)
    isBlocked = true;
 
  if (isBlocked)
    digitalWrite(LED_PIN, HIGH);
  else
    digitalWrite(LED_PIN, LOW);
 
  boolean isStuck 
    = (g_numTurnSteps > g_maxTurnSteps
      || g_numStepsForward > g_maxStepsForward);
 
  if (g_ebrake == EBRAKE_STOP && !isBlocked)
  {
    // /unstuck, ready for go signal
    g_ebrake = EBRAKE_WAIT; 
    return;
  }
  else if (g_ebrake == EBRAKE_WAIT && isBlocked)
  {
    // "Go!"
    ResetUltrasonic(EBRAKE_GO);
    return;
  }
  else if (g_ebrake == EBRAKE_GO && isStuck)
  {
    // stuck -- yank ebrake
    g_ebrake = EBRAKE_STOP;
    Stop();
    return;
  }
 
  if (g_ebrake != EBRAKE_GO)
  {
    // halt until !blocked and receive "Go" signal
    return;
  }
  
  if (isBlocked)
  {
    // evasive maneuvers!
    randomSeed(analogRead(A4));
    int randnum = random(300);
 
    if (distance > 30)
    {
      if (randnum > 190 && !g_rightFlag)
        TurnLeft();   
      else
        TurnRight();  
    }
    else
    {
      if (randnum > 190) 
        BackwardAndTurnLeft();
      else 
        BackwardAndTurnRight();
    }
  }
  else
  {
    // ONWARD!
    Forward();
  }
}
 
void ResetUltrasonic(int brakePos)
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps = 0;
  g_ebrake = brakePos;
  
  if (g_debug && g_mode == 0)
    Serial.println("Reset");
}
 
void Stop()
{
  MotorL.stop();
  MotorR.stop();
  
  if (g_debug)
    Serial.println("Stop");
}
 
void Forward()
{
  g_numStepsForward++;
  g_numTurnSteps = 0;
  g_rightFlag = false;
 
  MotorL.run(g_moveSpeed * g_leftTrim);
  MotorR.run(g_moveSpeed * g_rightTrim);
  
  if (g_debug)
    Serial.println("Forward");
}
 
void ForwardAndLeft()
{
  g_numStepsForward++;
  g_numTurnSteps++;
  g_rightFlag = false;
 
  MotorL.run(g_moveSpeed / 2);
  MotorR.run(g_moveSpeed);
  
  if (g_debug)
    Serial.println("Forward+Left");
}
 
void ForwardAndRight()
{
  g_numStepsForward++;
  g_numTurnSteps++;
  g_rightFlag = true;
 
  MotorL.run(g_moveSpeed);
  MotorR.run(g_moveSpeed / 2);
  
  if (g_debug)
    Serial.println("Forward+Right");
}
 
void Backward()
{
  g_rightFlag = false;
  g_numTurnSteps = 0;
  MotorL.run(-g_moveSpeed);
  MotorR.run(-g_moveSpeed);
}
void TurnLeft()
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps++;
 
  MotorL.run(-g_moveSpeed);
  MotorR.run(g_moveSpeed);
  
  if (g_debug)
    Serial.println("Left");
}
void TurnRight()
{
  g_rightFlag = true;
  g_numStepsForward = 0;
  g_numTurnSteps++;
 
  MotorL.run(g_moveSpeed);
  MotorR.run(-g_moveSpeed);
  
  if (g_debug)
    Serial.println("Right");
}
 
void BackwardAndTurnLeft()
{
  g_rightFlag = true;
  g_numStepsForward = 0;
  g_numTurnSteps++;
 
  MotorL.run(-g_moveSpeed/2);
  MotorR.run(-g_moveSpeed);
 
  if (g_debug)
    Serial.println("Backward+Left");
}
void BackwardAndTurnRight()
{
  g_rightFlag = false;
  g_numStepsForward = 0;
  g_numTurnSteps++;
 
  MotorL.run(-g_moveSpeed);
  MotorR.run(-g_moveSpeed/2);
 
  if (g_debug)
    Serial.println("Backward+Right");
}
 
void ChangeSpeed(int spd)
{
  g_moveSpeed = spd;
}

Robot Kit – Day Six

November 6, 2014 by Aaron

Oh the wonderful things a robot can do

It can go CHOO CHOO

It can go BEEP BEEP

I’m going to resist making any more mods until you suggest them. I also want to give mama a chance to tinker. Because she said, “But I wanted to do the BEEP!”

One thing we might have to do soon is give Bao a bumper. The ultrasonic sensor takes a beating from all the crashes. Anyway, with the new 3-wheel configuration, we haven’t had to recharge it for 3 days. The 4-wheel tank ran empty in just one day. But then again, we’ve only been in IR mode. Maybe the Ultrasonic processing is a power hog too.

And finally, it was time for new batteries. I strapped some Legos to the frame. You put "one door for going in, and one door for going out."

And finally, it was time for new batteries. Just for fun, I strapped some Legos to the frame. You made “one door for going in, and one door for going out.”

Robot Kit – Day Six (“What’s that sound downstairs?”)

November 3, 2014 by Aaron

What’s that sound coming from downstairs?

“I want his name to still be Bawa.”

Bonus: The mailman brought gifts! An 8-pack of Eneloops and one fast charger. I got that charger because it has a DC 12V input, which can be driven by cigarette lighter sockets and a foldable solar panel I’ve been thinking of getting.

Choo choo!

Mama gets a turn too, somewhat. And we learn to share

Robot Kit – Day Five

November 3, 2014 by Aaron

Here’s Bao with fresh batteries and the new program

I was impressed with how quickly you understood its algorithm.

We had a play date in the afternoon and Bao was an excellent babysitter

Later, I got excited when the CR2025 batteries came in the mail for the IR remote. So we upgraded Bao with IR control. You were a terrible pilot at first, and as you can see, we found out why when you ran away in the middle of playing.

It turned out that you had to go potty. You were a much better pilot after that

I was starting to wonder if we really wanted the tank mode. The tracks kept getting stuck, it ate too much power, it was heavier, and it wasn’t efficient (2 wheels driving 4 wheels, slack in the tracks, etc). The 3-wheeled car was starting to look like a better design. It’s simple like a FWD car, with each motor driving one wheel directly. So we converted Bao to a 3-wheeler tonight and you renamed him to Bawa.

Robot Kit – Day Four

November 1, 2014 by Aaron

“I want to call it a Sister Kit, not a Starter Kit.”

Its name is now Bow (as in Bow-wow). And it’s a girl.

Batteries are still charging. Meanwhile, I showed you the code and the instruction “Forward”. We’re learning how to “teach” the robot how to do things by sending it instructions. The first thing we’ll do is show it how to go forward. You said, “And then we’ll teach it to spin.” Good idea. Then I was thinking of teaching it how to use its “eyes” so it spins when you put your hand in front of it. Then maybe we’ll load the ultrasonic obstacle-avoidance program.

It’s alive! (Forward only)

New trick (Turn left – but not enough power)

After adding more juice to motors:

Peekaboo mode: “Ultrasonic Car” demo program with Forward() replaced with Stop():

Then we ran out of power 🙁

Update: Somehow I kept tinkering until 5am without batteries, but with the board attached to my computer. I couldn’t move the motors, but I could simulate it by printing to the SoftwareSerial. I added a “handbrake” mode so it pulls the handbrake if it’s stuck or if it gets bored. Then, to start it again, you first have to turn it so it’s no longer facing any obstacle. Then, give it the “Go” signal by waving in front of its eyes.



		
		
			
			

			
			/*************************************************************************
* File Name          : Makeblock Ultrasonic.ino
* Author             : Aaron
* Updated            : Aaron
* Version            : V1.0.0
* Date               : 10/31/2014
* Description        : Ultrasonic car with "Handbrake" and Hand Wave Go signal
                       connect on the M1 and M2 port of baseshield, the Ultrasonic sensor
                       connect on port 3.
* License            : CC-BY-SA 3.0
* Copyright (C) 2013 Maker Works Technology Co., Ltd. All right reserved.
* http://www.makeblock.cc/
**************************************************************************/
#include <Makeblock.h>
#include <Arduino.h>
#include <SoftwareSerial.h>
#include <Wire.h>

MeDCMotor MotorL(M1);  
MeDCMotor MotorR(M2);
MeUltrasonicSensor UltrasonicSensor(PORT_3);
int moveSpeed = 190;
int turnSpeed = 200;
int stepPeriod = 150;
int numStepsForward = 0;
int maxStepsForward = 3000 / stepPeriod;
int numTurnSteps = 0;
int maxTurnSteps = 3000 / stepPeriod;
boolean leftflag,rightflag;
int OBS_PIN = 13;
boolean debug = true;
int handbrake = 2; // 2 = full stop, 1 = wait for "go" signal, 0 = no brakes
long timeLastBlocked = 0;

void setup()
{
    randomSeed(analogRead(0));
    if (debug)
      Serial.begin(9600);
    pinMode(OBS_PIN, OUTPUT); // "obstructed" LED
    Reset();
}

void loop()
{
  if (millis() % stepPeriod == 0)
    doUltrasonicCar();
}

void doUltrasonicCar()
{
  //buzzerOff(); // isStuck makes buzz. This clears all buzzes on next iter 

  int distance = UltrasonicSensor.distanceCm();
  
  boolean isBlocked = (distance > 2 && distance < 40);
  if (isBlocked)
    timeLastBlocked = millis();
  else if (millis() - timeLastBlocked < 1000)
    isBlocked = true;

  boolean isStuck = (numTurnSteps > maxTurnSteps
                     || numStepsForward > maxStepsForward);
  
  if (isBlocked)
    digitalWrite(OBS_PIN, HIGH);
  else
    digitalWrite(OBS_PIN, LOW);

  if (handbrake == 2 && !isBlocked)
  {
    // /unstuck, ready for go signal
    handbrake = 1; 
    return;
  }
  else if (handbrake == 1 && isBlocked)
  {
    // "Go!"
    handbrake = 0;
    Reset();
    return;
  }
  else if (handbrake == 0 && isStuck)
  {
    handbrake = 2;
    Stop();
    //buzzerOn();
    return;
  }

  if (handbrake > 0)
    return;
  
  if (isBlocked)
  {
    // avoid obstacle
    int randnum=random(300);
    if (randnum > 150 && !rightflag)
      TurnLeft();   
    else
      TurnRight();  
  }
  else
  {
    // ONWARD!
    Forward();
  }
}

void Reset()
{
  leftflag=false;
  rightflag=false;
  numStepsForward = 0;
  numTurnSteps = 0;
  
  if (debug)
    Serial.println("Reset");
}

void Stop()
{
  MotorL.stop();
  MotorR.stop();
  
  if (debug)
    Serial.println("Stop");
}

void Forward()
{
  numStepsForward++;
  numTurnSteps = 0;
  leftflag=false;
  rightflag=false;

  MotorL.run(moveSpeed);
  MotorR.run(moveSpeed);
  
  if (debug)
    Serial.println("Forward");
}
void Backward()
{
  numTurnSteps = 0;
  MotorL.run(-moveSpeed);
  MotorR.run(-moveSpeed);
}
void TurnLeft()
{
  leftflag=true;
  numStepsForward = 0;
  numTurnSteps++;

  MotorL.run(-turnSpeed);
  MotorR.run(turnSpeed);
  
  if (debug)
    Serial.println("Left");
}
void TurnRight()
{
  rightflag=true;
  numStepsForward = 0;
  numTurnSteps++;

  MotorL.run(turnSpeed);
  MotorR.run(-turnSpeed);
  
  if (debug)
    Serial.println("Right");
}
			
				
					
				
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						/*************************************************************************
* File Name          : Makeblock Ultrasonic.ino
* Author             : Aaron
* Updated            : Aaron
* Version            : V1.0.0
* Date               : 10/31/2014
* Description        : Ultrasonic car with "Handbrake" and Hand Wave Go signal
                       connect on the M1 and M2 port of baseshield, the Ultrasonic sensor
                       connect on port 3.
* License            : CC-BY-SA 3.0
* Copyright (C) 2013 Maker Works Technology Co., Ltd. All right reserved.
* http://www.makeblock.cc/
**************************************************************************/
#include <Makeblock.h>
#include <Arduino.h>
#include <SoftwareSerial.h>
#include <Wire.h>
 
MeDCMotor MotorL(M1);  
MeDCMotor MotorR(M2);
MeUltrasonicSensor UltrasonicSensor(PORT_3);
int moveSpeed = 190;
int turnSpeed = 200;
int stepPeriod = 150;
int numStepsForward = 0;
int maxStepsForward = 3000 / stepPeriod;
int numTurnSteps = 0;
int maxTurnSteps = 3000 / stepPeriod;
boolean leftflag,rightflag;
int OBS_PIN = 13;
boolean debug = true;
int handbrake = 2; // 2 = full stop, 1 = wait for "go" signal, 0 = no brakes
long timeLastBlocked = 0;
 
void setup()
{
    randomSeed(analogRead(0));
    if (debug)
      Serial.begin(9600);
    pinMode(OBS_PIN, OUTPUT); // "obstructed" LED
    Reset();
}
 
void loop()
{
  if (millis() % stepPeriod == 0)
    doUltrasonicCar();
}
 
void doUltrasonicCar()
{
  //buzzerOff(); // isStuck makes buzz. This clears all buzzes on next iter 
 
  int distance = UltrasonicSensor.distanceCm();
  
  boolean isBlocked = (distance > 2 && distance < 40);
  if (isBlocked)
    timeLastBlocked = millis();
  else if (millis() - timeLastBlocked < 1000)
    isBlocked = true;
 
  boolean isStuck = (numTurnSteps > maxTurnSteps
                     || numStepsForward > maxStepsForward);
  
  if (isBlocked)
    digitalWrite(OBS_PIN, HIGH);
  else
    digitalWrite(OBS_PIN, LOW);
 
  if (handbrake == 2 && !isBlocked)
  {
    // /unstuck, ready for go signal
    handbrake = 1; 
    return;
  }
  else if (handbrake == 1 && isBlocked)
  {
    // "Go!"
    handbrake = 0;
    Reset();
    return;
  }
  else if (handbrake == 0 && isStuck)
  {
    handbrake = 2;
    Stop();
    //buzzerOn();
    return;
  }
 
  if (handbrake > 0)
    return;
  
  if (isBlocked)
  {
    // avoid obstacle
    int randnum=random(300);
    if (randnum > 150 && !rightflag)
      TurnLeft();   
    else
      TurnRight();  
  }
  else
  {
    // ONWARD!
    Forward();
  }
}
 
void Reset()
{
  leftflag=false;
  rightflag=false;
  numStepsForward = 0;
  numTurnSteps = 0;
  
  if (debug)
    Serial.println("Reset");
}
 
void Stop()
{
  MotorL.stop();
  MotorR.stop();
  
  if (debug)
    Serial.println("Stop");
}
 
void Forward()
{
  numStepsForward++;
  numTurnSteps = 0;
  leftflag=false;
  rightflag=false;
 
  MotorL.run(moveSpeed);
  MotorR.run(moveSpeed);
  
  if (debug)
    Serial.println("Forward");
}
void Backward()
{
  numTurnSteps = 0;
  MotorL.run(-moveSpeed);
  MotorR.run(-moveSpeed);
}
void TurnLeft()
{
  leftflag=true;
  numStepsForward = 0;
  numTurnSteps++;
 
  MotorL.run(-turnSpeed);
  MotorR.run(turnSpeed);
  
  if (debug)
    Serial.println("Left");
}
void TurnRight()
{
  rightflag=true;
  numStepsForward = 0;
  numTurnSteps++;
 
  MotorL.run(turnSpeed);
  MotorR.run(-turnSpeed);
  
  if (debug)
    Serial.println("Right");
}

Robot Kit – Day Three

November 1, 2014 by Aaron

Uh oh, we’re missing the brain bucket

The plastic rivets in the kit were a pain. Too small for my fingers. I fumbled for a long time and it wasn’t something you could help with. Finally it was time to put on the eyes.

Then you tried connecting the batteries to the brains. Beep!

Then we connected the brains to the eyes

But it did not work

The Arduino IDE upload to the robot failed with a stk500_getsync error.

We really wanted to turn it on. But it was getting late because we went trick-or-treating. So we had to save it for tomorrow.

Update: while you were asleep I figured out that I was following old instructions and using and old driver. The Makeblock websites were probably outdated in a few places. E.g., the old one said to select Arduino Uno. But what worked was using the Arduino Leonardo driver and choosing Arduino Leonardo as the board in the IDE. I uploaded the “Blink” test and the blue blinking LED was glorious. Then I tested the DC motors. One track spun the wrong way so I reversed the wires. Now both tracks spun forward with the Forward instruction as they should. The motors were wimpy because it looks like the batteries didn’t come pre-charged. So pop them in the charger, and I spent some time “child-proofing” the structure for j. A few twist-ties helped secure the brain bucket from tugging and snatching. We are ready for tomorrow. I didn’t want to introduce all these extra complications for you tomorrow; I wasn’t sure if I would lose your attention. But maybe I’m not giving you enough credit and I should have?

Secret Science Lab

Surprising adventures with Science (and kids)!

Monthly Archives: November 2014

How to build a Makeblock Bluetooth/WiFi Cellbot car

LG Optimus Dynamic – perfect cellbot phone?

Robot Kit – Day 7

PC to android smartphone recipe

Robot Kit – Day Six

Robot Kit – Day Six (“What’s that sound downstairs?”)

Robot Kit – Day Five

Robot Kit – Day Four

Robot Kit – Day Three