HyperChiicken
Published © MIT

ARMin: Simple Robot Arm Controller Using Python

Control servos/motors connected to an Arduino robot arm kit using a Raspberry Pi, Python, and an Xbox 360 controller.

IntermediateFull instructions provided2 hours2,491
ARMin: Simple Robot Arm Controller Using Python

Things used in this project

Hardware components

Arduino UNO & Genuino UNO
Arduino UNO & Genuino UNO
×1
Raspberry Pi 3 Model B
Raspberry Pi 3 Model B
×1
Adeept Robot Arm Kit
×1
18650 li-ion battery
×2
xbox 360 controller
×1

Hand tools and fabrication machines

Screwdriver

Story

Read more

Schematics

Block Diagram

Code

arduino-control.py

Python
This is the code to be run on your Raspberry Pi. Depending on what permission level you have, you can use -- sudo python arduino-control.py -- on the command line
#!/usr/bin/env python
from __future__ import print_function
import xbox
from Arduino import Arduino
import time

# Define Arduino variables
servo1 = 9
servo2 = 6
servo3 = 5
servo4 = 3
servo5 = 11

board = Arduino()
board.Servos.attach(servo1)
board.Servos.attach(servo2)
board.Servos.attach(servo3)
board.Servos.attach(servo4)
board.Servos.attach(servo5)

angle1 = 90
angle2 = 90
angle3 = 90
angle4 = 90
angle5 = 0

# Format floating point number to string format -x.xxx
def fmtFloat(n):
    return '{:6.3f}'.format(n)

# Print one or more values without a line feed
def show(*args):
    for arg in args:
        print(arg, end="")

# Print true or false value based on a boolean, without linefeed
def showIf(boolean, ifTrue, ifFalse=" "):
    if boolean:
        show(ifTrue)
    else:
        show(ifFalse)

# Move servo with respect to the left analog stick X values limited to the min-max angle set 
def leftXmove(servonum,minAngle,maxAngle):
    angle = angle1
    if int(joy.leftX()) > 0:
        angle = angle - 2 
        if angle <= minAngle:
            angle = minAngle
        return angle
    elif int(joy.leftX()) < 0:
        angle = angle + 2
        if angle >= maxAngle:
            angle = maxAngle
        return angle
    else:
        return angle
    
# Move servo with respect to the left analog stick X values limited to the min-max angle set 
def leftYmove(servonum,minAngle,maxAngle):
    angle = angle2
    if int(joy.leftY()) > 0:
        angle = angle - 2
        if angle <= minAngle:
            angle = minAngle
        return angle
    elif int(joy.leftY()) < 0:
        angle = angle + 2
        if angle >- maxAngle:
            angle = maxAngle
        return angle
    else:
        return angle

# Move servo with respect to the right analog stick Y values limited to the min-max angle set     
def rightYmove(servonum,minAngle,maxAngle):
    angle = angle3
    if int(joy.rightY()) > 0:
        angle = angle - 2
        if angle <= minAngle:
            angle = minAngle
        return angle
    elif int(joy.rightY()) < 0:
        angle = angle + 2
        if angle >= maxAngle:
            angle = maxAngle
        return angle
    else:
        return angle

	
# Move servo with respect to the right analog stick X values limited to the min-max angle set     
def rightXmove(servonum,minAngle,maxAngle):
    angle = angle4
    if int(joy.rightX()) > 0:
        angle = angle - 2
        if angle <= minAngle:
            angle = minAngle
        return angle
    elif int(joy.rightX()) < 0:
        angle = angle + 2
        if angle >= maxAngle:
            angle = maxAngle
        return angle
    else:
        return angle

# Move servo when right trigger is used
def rightTrigmove(servonum,minAngle,maxAngle):
    angle5 = minAngle
    if int(joy.rightTrigger()) > 0:
        angle5 = maxAngle
        board.Servos.write(servonum,angle5)
    else:
        board.Servos.write(servonum,minAngle)

# Instantiate the controller
joy = xbox.Joystick()

# Show various axis and button states until Back button is pressed
print("Xbox controller sample: Press Back button to exit")
while not joy.Back():
    # Show connection status
    show("Connected:")
    showIf(joy.connected(), "Y", "N")    
    # Left analog stick
    show("  Left X/Y:", fmtFloat(joy.leftX()), "/", fmtFloat(joy.leftY()))      
    # Right analog stick
    show("  Right X/Y:", fmtFloat(joy.rightX()), "/", fmtFloat(joy.rightY()))  
    # Right trigger
    show("  RightTrg:", fmtFloat(joy.rightTrigger()))
    # Poll controller leftX values and move servo1 accordingly
    angle1 = leftXmove(servo1,0,180)
    board.Servos.write(servo1,angle1)
    # Poll controller leftY values and move servo2 accordingly
    angle2 = leftYmove(servo2,0,120)
    board.Servos.write(servo2,angle2)
    # Poll controller rightY values and move servo3 accordingly
    angle3 = rightYmove(servo3,0,180)
    board.Servos.write(servo3,angle3)
    # Poll controller rightX values and move servo4 accordingly
    angle4 = rightXmove(servo4,0,180)
    board.Servos.write(servo4,angle4)
    # Move claw conencted to servo5 depending on right trigger value
    rightTrigmove(servo5,0,90)
    # A/B/X/Y buttons
    show("  Buttons:")
    showIf(joy.A(), "A")
    showIf(joy.B(), "B")
    showIf(joy.X(), "X")
    showIf(joy.Y(), "Y") 
    # Dpad U/D/L/R
    show("  Dpad:")
    showIf(joy.dpadUp(),    "U")
    showIf(joy.dpadDown(),  "D")
    showIf(joy.dpadLeft(),  "L")
    showIf(joy.dpadRight(), "R")  
    # Move cursor back to start of line
    show(chr(13))
# Close out when done
joy.close()

prototype.ino

Arduino
Upload this sketch to your Arduino
#include <SoftwareSerial.h>
#include <Wire.h>
#include <Servo.h>
#include <EEPROM.h>

void Version(){
  Serial.println(F("V0.6"));
}


SoftwareSerial *sserial = NULL;
Servo servos[8];
int servo_pins[] = {0, 0, 0, 0, 0, 0, 0, 0};
boolean connected = false;

int Str2int (String Str_value)
{
  char buffer[10]; //max length is three units
  Str_value.toCharArray(buffer, 10);
  int int_value = atoi(buffer);
  return int_value;
}

void split(String results[], int len, String input, char spChar) {
  String temp = input;
  for (int i=0; i<len; i++) {
    int idx = temp.indexOf(spChar);
    results[i] = temp.substring(0,idx);
    temp = temp.substring(idx+1);
  }
}

uint8_t readCapacitivePin(String data) {
  int pinToMeasure = Str2int(data);
  // readCapacitivePin
  //  Input: Arduino pin number
  //  Output: A number, from 0 to 17 expressing
  //  how much capacitance is on the pin
  //  When you touch the pin, or whatever you have
  //  attached to it, the number will get higher
  //  http://playground.arduino.cc/Code/CapacitiveSensor
  //
  // Variables used to translate from Arduino to AVR pin naming
  volatile uint8_t* port;
  volatile uint8_t* ddr;
  volatile uint8_t* pin;
  // Here we translate the input pin number from
  //  Arduino pin number to the AVR PORT, PIN, DDR,
  //  and which bit of those registers we care about.
  byte bitmask;
  port = portOutputRegister(digitalPinToPort(pinToMeasure));
  ddr = portModeRegister(digitalPinToPort(pinToMeasure));
  bitmask = digitalPinToBitMask(pinToMeasure);
  pin = portInputRegister(digitalPinToPort(pinToMeasure));
  // Discharge the pin first by setting it low and output
  *port &= ~(bitmask);
  *ddr  |= bitmask;
  delay(1);
  // Make the pin an input with the internal pull-up on
  *ddr &= ~(bitmask);
  *port |= bitmask;

  // Now see how long the pin to get pulled up. This manual unrolling of the loop
  // decreases the number of hardware cycles between each read of the pin,
  // thus increasing sensitivity.
  uint8_t cycles = 17;
       if (*pin & bitmask) { cycles =  0;}
  else if (*pin & bitmask) { cycles =  1;}
  else if (*pin & bitmask) { cycles =  2;}
  else if (*pin & bitmask) { cycles =  3;}
  else if (*pin & bitmask) { cycles =  4;}
  else if (*pin & bitmask) { cycles =  5;}
  else if (*pin & bitmask) { cycles =  6;}
  else if (*pin & bitmask) { cycles =  7;}
  else if (*pin & bitmask) { cycles =  8;}
  else if (*pin & bitmask) { cycles =  9;}
  else if (*pin & bitmask) { cycles = 10;}
  else if (*pin & bitmask) { cycles = 11;}
  else if (*pin & bitmask) { cycles = 12;}
  else if (*pin & bitmask) { cycles = 13;}
  else if (*pin & bitmask) { cycles = 14;}
  else if (*pin & bitmask) { cycles = 15;}
  else if (*pin & bitmask) { cycles = 16;}

  // Discharge the pin again by setting it low and output
  //  It's important to leave the pins low if you want to
  //  be able to touch more than 1 sensor at a time - if
  //  the sensor is left pulled high, when you touch
  //  two sensors, your body will transfer the charge between
  //  sensors.
  *port &= ~(bitmask);
  *ddr  |= bitmask;

  //return cycles;
  Serial.println(cycles);
}

void Tone(String data){
  int idx = data.indexOf('%');
  int len = Str2int(data.substring(0,idx));
  String data2 = data.substring(idx+1);
  int idx2 = data2.indexOf('%');
  int pin = Str2int(data2.substring(0,idx2));
  String data3 = data2.substring(idx2+1);
  String melody[len*2];
  split(melody,len*2,data3,'%');

  for (int thisNote = 0; thisNote < len; thisNote++) {
    int noteDuration = 1000/Str2int(melody[thisNote+len]);
    int note = Str2int(melody[thisNote]);
    tone(pin, note, noteDuration);
    int pause = noteDuration * 1.30;
    delay(pause);
    noTone(pin);
  }
}

void ToneNo(String data){
  int pin = Str2int(data);
  noTone(pin);
}

void DigitalHandler(int mode, String data){
      int pin = Str2int(data);
    if(mode<=0){ //read
        Serial.println(digitalRead(pin));
    }else{
        if(pin <0){
            digitalWrite(-pin,LOW);
        }else{
            digitalWrite(pin,HIGH);
        }
        //Serial.println('0');
    }
}

void AnalogHandler(int mode, String data){
     if(mode<=0){ //read
        int pin = Str2int(data);
        Serial.println(analogRead(pin));
    }else{
        String sdata[2];
        split(sdata,2,data,'%');
        int pin = Str2int(sdata[0]);
        int pv = Str2int(sdata[1]);
        analogWrite(pin,pv);
    }
}

void ConfigurePinHandler(String data){
    int pin = Str2int(data);
    if(pin <=0){
        pinMode(-pin,INPUT);
    }else{
        pinMode(pin,OUTPUT);
    }
}

void shiftOutHandler(String data) {
    String sdata[4];
    split(sdata, 4, data, '%');
    int dataPin = sdata[0].toInt();
    int clockPin = sdata[1].toInt();
    String bitOrderName = sdata[2];
    byte value = (byte)(sdata[3].toInt());
    if (bitOrderName == "MSBFIRST") {
       shiftOut(dataPin, clockPin, MSBFIRST, value);
    } else {
       shiftOut(dataPin, clockPin, LSBFIRST, value);
    }
}

void shiftInHandler(String data) {
    String sdata[3];
    split(sdata, 3, data, '%');
    int dataPin = sdata[0].toInt();
    int clockPin = sdata[1].toInt();
    String bitOrderName = sdata[2];
    int incoming;
    if (bitOrderName == "MSBFIRST") {
       incoming = (int)shiftIn(dataPin, clockPin, MSBFIRST);
    } else {
       incoming = (int)shiftIn(dataPin, clockPin, LSBFIRST);
    }
    Serial.println(incoming);
}

void SS_set(String data){
  delete sserial;
  String sdata[3];
  split(sdata,3,data,'%');
  int rx_ = Str2int(sdata[0]);
  int tx_ = Str2int(sdata[1]);
  int baud_ = Str2int(sdata[2]);
  sserial = new SoftwareSerial(rx_, tx_);
  sserial->begin(baud_);
  Serial.println("ss OK");
}

void SS_write(String data) {
 int len = data.length()+1;
 char buffer[len];
 data.toCharArray(buffer,len);
 Serial.println("ss OK");
 sserial->write(buffer);
}
void SS_read(String data) {
 char c = sserial->read();
 Serial.println(c);
}

void pulseInHandler(String data){
    int pin = Str2int(data);
    long duration;
    if(pin <=0){
          pinMode(-pin, INPUT);
          duration = pulseIn(-pin, LOW);
    }else{
          pinMode(pin, INPUT);
          duration = pulseIn(pin, HIGH);
    }
    Serial.println(duration);
}

void pulseInSHandler(String data){
    int pin = Str2int(data);
    long duration;
    if(pin <=0){
          pinMode(-pin, OUTPUT);
          digitalWrite(-pin, HIGH);
          delayMicroseconds(2);
          digitalWrite(-pin, LOW);
          delayMicroseconds(5);
          digitalWrite(-pin, HIGH);
          pinMode(-pin, INPUT);
          duration = pulseIn(-pin, LOW);
    }else{
          pinMode(pin, OUTPUT);
          digitalWrite(pin, LOW);
          delayMicroseconds(2);
          digitalWrite(pin, HIGH);
          delayMicroseconds(5);
          digitalWrite(pin, LOW);
          pinMode(pin, INPUT);
          duration = pulseIn(pin, HIGH);
    }
    Serial.println(duration);
}

void SV_add(String data) {
    String sdata[3];
    split(sdata,3,data,'%');
    int pin = Str2int(sdata[0]);
    int min = Str2int(sdata[1]);
    int max = Str2int(sdata[2]);
    int pos = -1;
    for (int i = 0; i<8;i++) {
        if (servo_pins[i] == pin) { //reset in place
            servos[pos].detach();
            servos[pos].attach(pin, min, max);
            servo_pins[pos] = pin;
            Serial.println(pos);
            return;
            }
        }
    for (int i = 0; i<8;i++) {
        if (servo_pins[i] == 0) {pos = i;break;} // find spot in servo array
        }
    if (pos == -1) {;} //no array position available!
    else {
        servos[pos].attach(pin, min, max);
        servo_pins[pos] = pin;
        Serial.println(pos);
        }
}

void SV_remove(String data) {
    int pos = Str2int(data);
    servos[pos].detach();
    servo_pins[pos] = 0;
}

void SV_read(String data) {
    int pos = Str2int(data);
    int angle;
    angle = servos[pos].read();
    Serial.println(angle);
}

void SV_write(String data) {
    String sdata[2];
    split(sdata,2,data,'%');
    int pos = Str2int(sdata[0]);
    int angle = Str2int(sdata[1]);
    servos[pos].write(angle);
}

void SV_write_ms(String data) {
    String sdata[2];
    split(sdata,2,data,'%');
    int pos = Str2int(sdata[0]);
    int uS = Str2int(sdata[1]);
    servos[pos].writeMicroseconds(uS);
}

void sizeEEPROM() {
    Serial.println(E2END + 1);
}

void EEPROMHandler(int mode, String data) {
    String sdata[2];
    split(sdata, 2, data, '%');
    if (mode == 0) {
        EEPROM.write(Str2int(sdata[0]), Str2int(sdata[1]));
    } else {
        Serial.println(EEPROM.read(Str2int(sdata[0])));
    }
}

void SerialParser(void) {
  char readChar[64];
  Serial.readBytesUntil(33,readChar,64);
  String read_ = String(readChar);
  //Serial.println(readChar);
  int idx1 = read_.indexOf('%');
  int idx2 = read_.indexOf('$');
  // separate command from associated data
  String cmd = read_.substring(1,idx1);
  String data = read_.substring(idx1+1,idx2);

  // determine command sent
  if (cmd == "dw") {
      DigitalHandler(1, data);
  }
  else if (cmd == "dr") {
      DigitalHandler(0, data);
  }
  else if (cmd == "aw") {
      AnalogHandler(1, data);
  }
  else if (cmd == "ar") {
      AnalogHandler(0, data);
  }
  else if (cmd == "pm") {
      ConfigurePinHandler(data);
  }
  else if (cmd == "ps") {
      pulseInSHandler(data);
  }
  else if (cmd == "pi") {
      pulseInHandler(data);
  }
  else if (cmd == "ss") {
      SS_set(data);
  }
  else if (cmd == "sw") {
      SS_write(data);
  }
  else if (cmd == "sr") {
      SS_read(data);
  }
  else if (cmd == "sva") {
      SV_add(data);
  }
  else if (cmd == "svr") {
      SV_read(data);
  }
 else if (cmd == "svw") {
      SV_write(data);
  }
 else if (cmd == "svwm") {
      SV_write_ms(data);
  }
  else if (cmd == "svd") {
      SV_remove(data);
  }
  else if (cmd == "version") {
      Version();
  }
  else if (cmd == "to") {
      Tone(data);
  }
  else if (cmd == "nto") {
      ToneNo(data);
  }
  else if (cmd == "cap") {
      readCapacitivePin(data);
  }
  else if (cmd == "so") {
      shiftOutHandler(data);
  }
  else if (cmd == "si") {
      shiftInHandler(data);
  }
  else if (cmd == "eewr") {
      EEPROMHandler(0, data);
  }
  else if (cmd == "eer") {
      EEPROMHandler(1, data);
  }
  else if (cmd == "sz") {
      sizeEEPROM();
  }
}

void setup()  {
  Serial.begin(115200);
    while (!Serial) {
      ; // wait for serial port to connect. Needed for Leonardo only
    }
  Serial.println("connected");
}

void loop() {
  SerialParser();
}

blink.py

Python
Run this to check if the Arduino-python3 module is working
#!/usr/bin/env python
"""
 Blinks an LED on digital pin 13
 in 1 second intervals
"""

from Arduino import Arduino
import time

board = Arduino() # plugged in via USB, serial com at rate 115200
board.pinMode(13, "OUTPUT")

while True:
    board.digitalWrite(13, "LOW")
    time.sleep(1)
    board.digitalWrite(13, "HIGH")
    time.sleep(1)

Credits

HyperChiicken

HyperChiicken

9 projects • 12 followers
I cobble things together :]

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