Md. Khairul Alam
Published © GPL3+

Walaarm: Walabot-Powered Robotic Arm

A robotic arm which can pick an object from any random location.

AdvancedWork in progress10 hours4,826

Things used in this project

Story

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Schematics

Block diagram of the System

Walaarm a93aaovguk

Schematic

The arm contains 5 micro servo motor. The motors are connected sequentially from the top (gripper) to bottom.
Arm schematic wct0kns5ru

Code

lambda_function

Python
Python code for AWS Lambda
"""
This sample demonstrates a simple skill built with the Amazon Alexa Skills Kit.
The Intent Schema, and Sample Utterances for this skill, as well
as testing instructions are located at http://amzn.to/1LzFrj6
 
The code is developed by:
	Md. Khairul Alam
	February, 2018
For additional samples, visit the Alexa Skills Kit Getting Started guide at
http://amzn.to/1LGWsLG
"""
 
from __future__ import print_function
import urllib2
import xml.etree.ElementTree as etree
from datetime import datetime as dt
import time
import paho.mqtt.client as mqtt

received_message = ""
user = ""
mqtt_topic = ""
# Define event callbacks
def on_connect(client, userdata, flags, rc):
    print("rc: " + str(rc))

def on_message(client, obj, msg):
    received_message = str(msg.payload)
    print(msg.topic + " " + str(msg.qos) + " " + received_message)


def on_subscribe(client, obj, mid, granted_qos):
    print("Subscribed: " + str(mid) + " " + str(granted_qos))
	
client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.on_subscribe = on_subscribe

#client.username_pw_set("cnpemclt", "ccZRVtdCTqID")
client.connect("iot.eclipse.org", "1883")

#client.connect("m12.cloudmqtt.com", 15708, 60)

# Start subscribe, with QoS level 0
client.subscribe("test/robot", 0)



def lambda_handler(event, context):
    """ Route the incoming request based on type (LaunchRequest, IntentRequest,
    etc.) The JSON body of the request is provided in the event parameter.
    """
    print("event.session.application.applicationId=" +
          event['session']['application']['applicationId'])
    print("event.session.application.userId=" +
          event['session']['user']['userId'])      
    #char = event['session']['user']['userId']
    #first 10 char from used id will be used to generate an unique topic
    #common part of the user id is deducted
    print(event['session']['user']['userId'][18:28])
    global user
    global mqtt_topic
    user = event['session']['user']['userId'][18:28]
    topic = "WALABOT/ROBOT/ARM/"
    mqtt_topic = topic + user
    print(mqtt_topic)
    """
    Uncomment this if statement and populate with your skill's application ID to
    prevent someone else from configuring a skill that sends requests to this
    function.
    """
    # if (event['session']['application']['applicationId'] !=
    #         "amzn1.echo-sdk-ams.app.[unique-value-here]"):
    #     raise ValueError("Invalid Application ID")
 
    if event['session']['new']:
        on_session_started({'requestId': event['request']['requestId']},
                           event['session'])
 
    if event['request']['type'] == "LaunchRequest":
        return on_launch(event['request'], event['session'])
    elif event['request']['type'] == "IntentRequest":
        return on_intent(event['request'], event['session'])
    elif event['request']['type'] == "SessionEndedRequest":
        return on_session_ended(event['request'], event['session'])
 
 
def on_session_started(session_started_request, session):
    """ Called when the session starts """
 
    print("on_session_started requestId=" + session_started_request['requestId']
          + ", sessionId=" + session['sessionId'])
 
 
def on_launch(launch_request, session):
    """ Called when the user launches the skill without specifying what they
    want
    """
 
    print("on_launch requestId=" + launch_request['requestId'] +
          ", sessionId=" + session['sessionId'])
    # Dispatch to your skill's launch
    return get_welcome_response()
 
 
def on_intent(intent_request, session):
    """ Called when the user specifies an intent for this skill """
 
    print("on_intent requestId=" + intent_request['requestId'] +
          ", sessionId=" + session['sessionId'])
 
    intent = intent_request['intent']
    intent_name = intent_request['intent']['name']
 
    # Dispatch to your skill's intent handlers
    if intent_name == "PickObjectIntent":
        return pick_object(intent, session)
    elif intent_name == "AMAZON.HelpIntent":
        return get_help()
    elif intent_name == "AMAZON.StopIntent" or intent_name == "AMAZON.CancelIntent":
        return session_end(intent, session)
    else:
        raise ValueError("Invalid intent")

 
def on_session_ended(session_ended_request, session):
    """ Called when the user ends the session.
 
    Is not called when the skill returns should_end_session=true
    """
    print("on_session_ended requestId=" + session_ended_request['requestId'] +
          ", sessionId=" + session['sessionId'])
    # add cleanup logic here
 
# --------------- Functions that control the skill's behavior ------------------
 
 
def get_welcome_response():
    """ If we wanted to initialize the session to have some attributes we could
    add those here
    """
 
    session_attributes = {}
    card_title = "Welcome"
    speech_output = "Welcome to the wala-arm application. I can pick an object from any random location " \
                    "by the help of Wala-bot. To know how to configure Wala-bot just say help, "\
                    "or to pick an object you can ask me, 'pick the object.'" 
                
    # If the user either does not reply to the welcome message or says something
    # that is not understood, they will be prompted again with this text.
    reprompt_text = "To pick an object just ask me, pick the object." 
                  
    should_end_session = False
    #myMQTTClient.publish("test/door", "welcome", 0)
    return build_response(session_attributes, build_speechlet_response(
        card_title, speech_output, reprompt_text, should_end_session))
		
def get_help():
    """ If we wanted to initialize the session to have some attributes we could
    add those here
    """
    global user
    temp = user
    count = 0
    while count<20:
        temp = temp[:count] + ' ' + temp[count:] #added a space after every character
        count+=2
    session_attributes = {}
    card_title = "Help"
    speech_output = "I am sending an MQTT message to the Raspberry Pi, connected with Wala-bot. " \
                    " Use wala-bot/ robot/ arm/ " + temp + ", as your MQTT topic. "\
                    " I am spelling the last word again, " + temp + " . Use block letters for the topic name."\
                    " For details please visit hackster.io and search for Wala-arm." \
                    
  
    # If the user either does not reply to the welcome message or says something
    # that is not understood, they will be prompted again with this text.
    reprompt_text = "I am waiting for your command."
    should_end_session = False
    #myMQTTClient.publish("test/door", "welcome", 0)
    return build_response(session_attributes, build_speechlet_response(
        card_title, speech_output, reprompt_text, should_end_session))

def pick_object(intent, session):
    """ If we wanted to initialize the session to have some attributes we could
    add those here
    """
    #client.publish("walabot/robot/arm/...", "pick")
    global mqtt_topic
    client.publish(mqtt_topic, "pick")
    time.sleep(2)
    session_attributes = {}
    card_title = "Picking Object"
    speech_output = "OK."
    # If the user either does not reply to the welcome message or says something
    # that is not understood, they will be prompted again with this text.
    reprompt_text = ""
    should_end_session = True
    return build_response(session_attributes, build_speechlet_response(
        card_title, speech_output, reprompt_text, should_end_session))
 

def session_end(intent, session):
    """ If we wanted to initialize the session to have some attributes we could
    add those here
    """
    session_attributes = {}
    card_title = "End"
    speech_output = "Thank you for calling me. Have a nice day!"
    
    # If the user either does not reply to the welcome message or says something
    # that is not understood, they will be prompted again with this text.
    reprompt_text = ""
    should_end_session = True
    return build_response(session_attributes, build_speechlet_response(
        card_title, speech_output, reprompt_text, should_end_session))        
 
# --------------- Helpers that build all of the responses ----------------------
 
 
def build_speechlet_response(title, output, reprompt_text, should_end_session):
    return {
        'outputSpeech': {
            'type': 'PlainText',
            'text': output
        },
        'card': {
            'type': 'Simple',
            'title': title,
            'content': output
        },
        'reprompt': {
            'outputSpeech': {
                'type': 'PlainText',
                'text': reprompt_text
            }
        },
        'shouldEndSession': should_end_session
    }
 
 
def build_response(session_attributes, speechlet_response):
    return {
        'version': '1.0',
        'sessionAttributes': session_attributes,
        'response': speechlet_response
    }

walaarm

Python
Code for raspberry pi
from __future__ import print_function
from sys import platform
from os import system
import time
import serial
from imp import load_source
import paho.mqtt.client as mqtt

#ser = serial.Serial('/dev/ttyACM0',9600)
ser = serial.Serial('/dev/ttyAMA0',9600)

received_message = ""

# Define event callbacks
def on_connect(client, userdata, flags, rc):
    print("rc: " + str(rc))

def on_message(client, obj, msg):
    received_message = str(msg.payload)
    print(received_message)
    if received_message == 'pick':
        WalabotAPI.Start()
        WalabotAPI.StartCalibration()
        WalabotAPI.Trigger()  # initiates a scan and records signals
        targets = WalabotAPI.GetImagingTargets() # provides a list of identified targetsc
        system('cls' if platform == 'win32' else 'clear')  # clear the terminal
        for i, t in enumerate(targets):
            print('Target #{}\nx = {}\ny = {}\nz = {}\n'.format(
                i+1, t.xPosCm, t.yPosCm, t.zPosCm))
            if t.yPosCm <-1 and t.zPosCm <1: #i am taking three random position
                print('pos1')
                position = 'pos1'
            elif t.yPosCm >1 and t.zPosCm >1:
                print('pos2')
                position = 'pos2'
            elif t.yPosCm >3 and t.zPosCm >2:
                print('pos3')
                position = 'pos3'
            ser.write(position)
            ser.write('\n')
        WalabotAPI.Stop()  # stops Walabot when finished scanning
            
        

def on_subscribe(client, obj, mid, granted_qos):
    print("Subscribed: " + str(mid) + " " + str(granted_qos))
	
client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.on_subscribe = on_subscribe

client.connect("iot.eclipse.org", "1883")
client.subscribe("WALABOT/ROBOT/ARM/XXXXXXXXXX", 0)
#replace XXXXXXXXXX by the character alexa spells from user id
#run the Wala-arm skill and ask for help to get the character sequence
#this 10 character will be unique for every user
WalabotAPI = load_source('WalabotAPI',
 '/usr/share/walabot/python/WalabotAPI.py')
 
R_MIN, R_MAX, R_RES = 2, 50, 5  # SetArenaR values
THETA_MIN, THETA_MAX, THETA_RES = -25, 5, 2  # SetArenaTheta values
PHI_MIN, PHI_MAX, PHI_RES = -75, 75, 2  # SetArenaPhi values
TSHLD = 5  # SetThreshold value
VELOCITY_THRESHOLD = 0.7  # captured vel bigger than that counts as key-press

WalabotAPI.Init()  # load the WalabotSDK to the Python wrapper
WalabotAPI.SetSettingsFolder()
WalabotAPI.ConnectAny()  # establishes communication with the Walabot
WalabotAPI.SetProfile(WalabotAPI.PROF_SENSOR)
WalabotAPI.SetArenaR(R_MIN, R_MAX, R_RES)
WalabotAPI.SetArenaTheta(THETA_MIN, THETA_MAX, THETA_RES)
WalabotAPI.SetArenaPhi(PHI_MIN, PHI_MAX, PHI_RES)
WalabotAPI.SetThreshold(TSHLD)
WalabotAPI.SetDynamicImageFilter(WalabotAPI.FILTER_TYPE_MTI)
#WalabotAPI.Start()
#WalabotAPI.StartCalibration()

#client.loop_forever()
rc = 0
while rc == 0:
    rc = client.loop()
print("rc: " + str(rc))

#WalabotAPI.Stop()  # stops Walabot when finished scanning
#WalabotAPI.Disconnect() # stops communication with Walabot

Code for Arduino

Arduino
This sketch if for the Arduino connected with the Robotic Arm
/*************************************
 * Author: Md. Khairul Alam
 * This code is for controlling a robotic arm containing 5 servos
 */

#include <Servo.h>

Servo servo1, servo2, servo3, servo4, servo5;
String inputString = "";         // a string to hold incoming data
boolean stringComplete = false;  // whether the string is complete

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  servo1.attach(2);
  servo2.attach(3);
  servo3.attach(4);
  servo4.attach(5);
  servo5.attach(6);
  inputString.reserve(200);
  nutral();
  unhold(); 
}

void loop() {
  
  if (stringComplete) {
    if(inputString == "pos1"){//if received message = pos1
        pick_pos1(); //pick the object from location 1
        delay(20);
      }
    else if(inputString == "pos2"){
        pick_pos2();
        delay(20);
      } 
    else if(inputString == "pos3"){
        pick_pos3();
        delay(20);
      }  
    // clear the string:
    inputString = "";
    stringComplete = false;
  }

}

void servo_rotate(int num, int value){
  switch(num){
    case 1:
    servo1.write(value);
    break;

    case 2:
    servo2.write(value);
    break;

    case 3:
    servo3.write(value);
    break;

    case 4:
    servo4.write(value);
    break;

    case 5:
    servo5.write(value);
    break;
    }
 }
 
//this function grip an object
void hold(){  
  for(int i=180; i>110; i--)
    {
      servo_rotate(1, i);
      delay(15);
      }  
  }
  
//this function unhold an object
void unhold(){
  for(int i=95; i<180; i++)
    {
      servo_rotate(1, i);
      delay(15);
      }
  }
  
//this function drive servo 5 to set x position in angle
void set_xpos(int pos){
  int previous_pos = servo5.read();
  if(pos>previous_pos){
    for(int i=previous_pos; i<pos; i+=2){
      servo_rotate(5, i);
      delay(25);
      }
    }
  if(pos<previous_pos){
    for(int i=previous_pos; i>pos; i-=2){
      servo_rotate(5, i);
      delay(25);
      }
    } 
 }
//set sevo 3 position
void set_3pos(int pos){
  int previous_pos = servo3.read();
  if(pos>previous_pos){
    for(int i=previous_pos; i<pos; i+=2){
      servo_rotate(3, i);
      delay(25);
      }
    }
  if(pos<previous_pos){
    for(int i=previous_pos; i>pos; i-=2){
      servo_rotate(3, i);
      delay(25);
      }
    } 
 }
//set sevo 2 position
void set_2pos(int pos){
  int previous_pos = servo2.read();
  if(pos>previous_pos){
    for(int i=previous_pos; i<pos; i+=2){
      servo_rotate(2, i);
      delay(25);
      }
    }
  if(pos<previous_pos){
    for(int i=previous_pos; i>pos; i-=2){
      servo_rotate(2, i);
      delay(25);
      }
    } 
 }
//set sevo 4 position
void set_4pos(int pos){
  int previous_pos = servo4.read();
  if(pos>previous_pos){
    for(int i=previous_pos; i<pos; i+=2){
      servo_rotate(4, i);
      delay(25);
      }
    }
  if(pos<previous_pos){
    for(int i=previous_pos; i>pos; i-=2){
      servo_rotate(4, i);
      delay(25);
      }
    } 
 }

//go to middle point
void nutral(){
  set_2pos(90);
  delay(300);
  set_3pos(60);
  delay(300);
  set_4pos(90);
  delay(300); 
  set_xpos(90); 
  delay(300);   
}
//pick an object from position 1
void pick_pos1(){
  delay(1000);
  set_xpos(140);
  delay(1000);
  set_3pos(80);
  delay(1000);
  set_4pos(140);  
  delay(1000);
  set_2pos(90);
  delay(1000);
  hold();
  delay(1000);
  set_3pos(60);
  delay(1000);
  delay(300);
  set_2pos(90);
  delay(300);
  set_4pos(90);
  delay(300);
  set_xpos(10);
  delay(300);
  set_3pos(100);
  delay(300);
  set_4pos(130);
  delay(300);
  unhold();
  delay(300);
  nutral(); 
}
//pick an object from position 2
void pick_pos2(){
  delay(300);
  set_xpos(120);
  delay(300);
  set_3pos(105);
  delay(300);
  set_2pos(140);  
  delay(300);
  set_4pos(100);
  delay(300);
  set_2pos(160); 
  delay(300);
  hold();
  delay(500);
  set_2pos(90);
  delay(500);
  set_3pos(80);
  delay(500);
  set_3pos(60);
  delay(500);
  set_4pos(90);
  delay(300);
  set_xpos(10);
  delay(300);
  set_3pos(100);
  delay(300);
  set_4pos(130);
  delay(300);
  unhold();
  delay(300);
  nutral(); 
 }
//pick an object from position 3
void pick_pos3(){
  delay(300);
  set_xpos(70);
  delay(300);
  set_3pos(110);
  delay(300);
  set_4pos(120);
  delay(300);
  set_2pos(100); 
  delay(300);
  hold();
  delay(500);
  set_2pos(90);
  delay(500);
  set_3pos(80);
  delay(500);
  set_3pos(60);
  delay(500);
  set_4pos(90);
  delay(300);
  set_xpos(10);
  delay(300);
  set_3pos(100);
  delay(300);
  set_4pos(130);
  delay(300);
  unhold();
  delay(300);
  nutral(); 
}

void serialEvent() {
  while (Serial.available()) {    
    // get the new byte:
    char inChar = (char)Serial.read();     
    // if the incoming character is a newline, set a flag
    // so the main loop can do something about it:
    if (inChar == '\n') {
      stringComplete = true;
    }
    else
    // add it to the inputString:  
      inputString += inChar;
  }
}

Alexa skill

JSON
JSON code for the skill Walaarm
{
    "interactionModel": {
        "languageModel": {
            "invocationName": "wala arm",
            "intents": [
                {
                    "name": "AMAZON.CancelIntent",
                    "samples": []
                },
                {
                    "name": "AMAZON.HelpIntent",
                    "samples": []
                },
                {
                    "name": "AMAZON.StopIntent",
                    "samples": []
                },
                {
                    "name": "PickObjectIntent",
                    "slots": [],
                    "samples": [
                        "hold the thing",
                        "hold the object",
                        "pick thing",
                        "pick boject",
                        "pick the thing",
                        "pick the object"
                    ]
                }
            ],
            "types": []
        }
    }
}

Credits

Md. Khairul Alam

Md. Khairul Alam

28 projects • 250 followers
Engineer, developer, maker, and hacker.

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