Mrinnovative
In this tutorial, I will share with you how to make a smart robotic arm. You can control this arm using a “Master” arm using potentiometers.
The “Slave” arm is comprised of servos and will run off of the potentiometer readings. This will mimic manual movements.
Along with this feature, the prototype is also smart because it can record positions and repeat them continuously.
This project is designed for people with experience using Arduino and electronics. Therefore, I wouldn’t recommend this project to absolute beginners.
You need basic understanding of using Servos, potentiometers, and programming knowledge.
COMPONENT REQUIRED
Arduino nano : - http://amzn.to/2BJYzxI
Servo motor : - http://amzn.to/2Ar89au
Tactile push button : -http://amzn.to/2BKPuEL
DC power jack : - http://amzn.to/2AwO8NP
Header pin : - http://amzn.to/2knXbfW
You can increase the number of joints to increase range of motion by increasing servos and potentiometers.
If you want to make your own arm you can use an Acrylic sheet or Popsicle sticks. As I have used.
You can even 3D print a design or use a CNC machine. Another option is to buy a Robotic Arm Kit,
which consists of everything needed for this project.
CIRCUIT DIAGRAM AND CUSTOM PCB
complete detail of the PCB you can find here :- https://oshwlab.com/sharmaz747/record-and-play-robotic-arm
I have try to build this circuit on bread-board and Zero PCB but all are fail because this option are not reliable,
this project is very sensitive to the value of potentiometer so I am not able to get the desire result I have fail so many times.
but Then I think about to try Custom PCB but my belief for PCB's are they must be so expensive but all of my fear was gone when I found JLCPCB.com really they are offering Quality PCB in very affordable rates, if you are also hesitate to try custom PCB just because you think they are very costly I will tell you don't wait just visit JLCPCB.com
If you seriously need quality PCB quickly in your hand then you must have to try JLCPCB PCB manufacturing service. They have Special offer of $2 for 1-4 Layer PCBs, free SMT assembly monthly. If new user signup today from this link JLCPCB.com you will get welcome coupons from JLCPCB.
SMT Assembly service of JLCPCB.com is cherry on top now get your PCB fully assembled and save your time and money Select components for your PCB from there Parts Library of 200k+ in-stock components they are offering $30 valued New User coupons & $24 SMT coupons every month $8.00 setup fee, and $0.0017 per joint
Now no need to order components separately for you PCB and get free from stress of soldering them on PCB just try PCB SMT assembly service and get you PCB with components pre assembled and ready for the project
👉 Try PCBA service of JLCPCB.com and save your time and money, get PCB ready for project, 200K+ components in library of JLCPCB.com as well as 3rd party parts to choose from. Assembly will support 10M+ parts from Digikey, mouser
👉 $30 valued New User coupons
👉 $24 SMT coupons every month
For more detials & offers please visit JLCPCB.com
- Follow the simple step to get this PCB board.
1 - Download the circuit board Gerber file: https://oshwlab.com/sharmaz747/record-and-play-robotic-arm
2 - Create an account using the link below: JLCPCB.com
3 - visit JLCPCB.com Add the Gerber file and place the order.
Carefully do the wiring as shown in drawing
Provide separate power supply (5V DC 1amps) to the Servo motors
Don't forget to short ground of both power source ( arduino + servo)
Please go through the attached images and video for better understanding..
I divide whole project in two parts
- Servo Motor assembly
- Potentiometer assembly
- Servo motor assembly: - Servo motor as J1, J2, J3, J4 fix the servo motors as shown in image use 3M tape to glue servo, use thin flexible plastic strip to make griper, make hole in center of each finger tie thread in that hole pass this thread from center hole and tie knot at the other end of thread with 4th servo motor’s knob, as you stretch thread finger get close vise versa. Fix whole arrangement on strong rigid base.
- Potentiometer assembly: - Fix potentiometer as shown in figure name potentiometer as do previous R3, R4, R5, R6 this time place R6 separately for easy access this potentiometer control gripper to pick and place. Potentiometer arrangement symmetry must be same as servo arm. Fix whole arrangement on strong rigid base.
ARDUINO CODE
/*
serial config:
Board: Arduiono Pro / Pro Mini
Port: tty.usbseriala400eMNr
Programmer: USBtinyISP
*/
// Definitionen
#include <Servo.h> // servo treiber
Servo servo_0;
Servo servo_1;
Servo servo_2;
Servo servo_3;
int sensorPin0 = A0; // Schulter
int sensorPin1 = A1; // Handfind
int sensorPin2 = A2; // Ellbogen
int sensorPin3 = A3; // Zange
int count0, arrayStep, arrayMax, countverz, Taster, stepsMax, steps, time = 1000, del = 1000, temp;
//arraystep = memory what pos in the array
//arrayMax = max steps we safed to array
//countverz = seems to be something to calculate the delay between complete moves
//Taster = Button //stepsMax = longest way a servo have to travel
//steps = single steps for a move between stored positions
unsigned int verz = 0;
long previousMillis1 = 0;
long previousMillis2 = 0;
long previousMillis3 = 0;
long previousMillis4 = 0;
long previousMicros = 0;
unsigned long currentMillis = millis();
unsigned long currentMicros = micros();
// arrays
int Delay[7] = {0,0,1,1,1,1,1}; // array to map gripper pot to delay in seconds
int SensVal[4]; // sensor value
float dif[4], ist[4], sol[4], dir[4]; // difference between stored position and momentary position
int joint0[180];// array for servo(s)
int joint1[180];
int joint2[180];
int joint3[180];
int top = 179; // we should not write over the end from a array
// status boolean playmode = false, Step = false;
void setup()
{ pinMode(4, INPUT); // sets the digital pin 4 as input pinMode(6, INPUT); pinMode(13, OUTPUT); // sets the digital pin 13 as outtput digitalWrite(13, HIGH); // sets the LED on servo_0.attach(3); // attaches the servo servo_1.attach(10); servo_2.attach(5); servo_3.attach(11); Serial.begin(115200); // Baudrate have to be same on the IDE Serial.println("mini robot ready..."); //delay(1000); digitalWrite(13, LOW);
}
void loop() // here we go!
{ currentMillis = millis(); // all is about timing currentMicros = micros(); // read the button Button(); if(!playmode) // manualy modus { if(currentMillis - previousMillis1 > 25) // 25miliseconds until next manual mode update { if (arrayStep < top) { previousMillis1 = currentMillis; //reset readPot(); // get the value from potentiometers mapping(); // map to milliseconds for servos move_servo(); // setz newservo position //record(); } // end counter < max } // end step check } // ende manualy move else if(playmode) // play { if (Step) // next step read from array { digitalWrite(13, HIGH); //LED if (arrayStep < arrayMax) // we not reach the end from stored data { arrayStep += 1; // next array pos Read(); // from the arrays calculate(); // find biggest travel distance and calculate the other 3 servos (the have to do smaler steps to be finished at same time!) Step = 0; digitalWrite(13, LOW); } else // array read finished > start over { arrayStep = 0; // calc_pause(); // delay between moves read from potentiometer countverz = 0; // used for the delay while(countverz < verz) // verz = time getting from calc_pause(); { // here we do loop and wait until next start over countverz += 1; calc_pause(); digitalWrite(13, HIGH); delay(25); digitalWrite(13, LOW); delay(975); } } //Serial.println(arrayStep); } else // do the servos! { if (currentMicros - previousMicros > time) // here we do a single micro step { // previousMicros = currentMicros; play_servo(); } } }// ende playmode
// ---------------------------------------------------------------------------------Hardware pause switch PIN 6 while (digitalRead(4) == false) { digitalWrite(13, HIGH); delay(500); digitalWrite(13, LOW); delay(500); }
// ---------------------------------------------------------------------------------- Textout serial // serial ausgabe 1 sek /*if(currentMillis - previousMillis2 > 5000) { previousMillis2 = currentMillis; /*count0 = 0; while(count0 < 4) { int val = SensVal[count0]; // val = map(val, 142, 888, 0, 180); Serial.println(val); //Serial.println("test"); count0 += 1; } Serial.println(playmode); Serial.println(arrayStep); Serial.println(arrayMax); Serial.println(" "); }*/
}
// ---------------------------------------------------------------------------------------- sub routinen
void calc_pause() // read pot and map to usable delay time after a complete move is done
{ readPot(); temp = SensVal[3]; if (temp < 0) temp = 0; temp = map(temp, 0, 680, 0 ,5); verz = Delay[temp]; // verz = delay in second Serial.print(temp); Serial.print(" "); Serial.print(verz); Serial.print(" "); Serial.println(countverz);
}
void readPot() // read analog inputs and add some offsets (mechanical corrections)
{ SensVal[0] = analogRead(sensorPin0); //SensVal[0] += -10; // rotate SensVal[1] = analogRead(sensorPin1); //SensVal[1] += 280; // Shoulder SensVal[2] = analogRead(sensorPin2); //SensVal[2] += -50; // hand SensVal[3] = analogRead(sensorPin3); // SensVal[3] += 0;// gripper Serial.print(SensVal[2]);Serial.print(" "); // CHECK
}
void mapping() // we need microsecond for the servos instead potentiometer values
{ ist[0] = map(SensVal[0], 150, 900, 600, 2400);// drehen ist[1] = map(SensVal[1], 1000, 100, 550, 2400);// Schulter ist[2] = map(SensVal[2], 120, 860, 400, 2500);// Hand ist[3] = map(SensVal[3], 1023, 0, 500, 2500);// Zange Serial.println(ist[2]); // CHECK
}
void record()
{ joint0[arrayStep] = ist[0]; // write positions in servo array joint1[arrayStep] = ist[1]; joint2[arrayStep] = ist[2]; joint3[arrayStep] = ist[3];
}
void Read()
{ sol[0] = joint0[arrayStep]; // read from the array sol[1] = joint1[arrayStep]; sol[2] = joint2[arrayStep]; sol[3] = joint3[arrayStep];
}
void move_servo()
{ servo_0.writeMicroseconds(ist[3]); // send milissecond values to servos servo_1.writeMicroseconds(ist[2]); servo_2.writeMicroseconds(ist[0]); servo_3.writeMicroseconds(ist[1]); }
// ------------------------------------------------------------ single steps calculating
void calculate()
{ // travel distance for each servo dif[0] = abs(ist[0]-sol[0]); dif[1] = abs(ist[1]-sol[1]); dif[2] = abs(ist[2]-sol[2]); dif[3] = abs(ist[3]-sol[3]);
// biggest travel way from all 4 servos stepsMax = max(dif[0],dif[1]); stepsMax = max(stepsMax,dif[2]); stepsMax = max(stepsMax,dif[3]); // stepsMax is the biggest distance a servo have to do beween momentary position and new pos read from the array //Serial.println(stepsMax); if (stepsMax < 500) // del(ay) between a single step is bigger is move is smaler. just looks cool del = 1200; else del = 600; // calculating single (micro) step for each servo // need that to do move all servos in a loop (stepsMax times done) with different values. // This makes all servos have done the traveling distance at same time if (sol[0] < ist[0]) dir[0] = 0-dif[0]/stepsMax; else dir[0] = dif[0]/stepsMax; if (sol[1] < ist[1]) dir[1] = 0-dif[1]/stepsMax; else dir[1] = dif[1]/stepsMax; if (sol[2] < ist[2]) dir[2] = 0-dif[2]/stepsMax; else dir[2] = dif[2]/stepsMax; if (sol[3] < ist[3]) dir[3] = 0-dif[3]/stepsMax; else dir[3] = dif[3]/stepsMax; //Serial.println(dir4);
}
void play_servo()
{ steps += 1; if (steps < stepsMax) // sure we not reach the end from a move { //time = del*5;// anfahr rampe if(steps == 20) time = del*4; // ramp up else if(steps == 40) time = del*3; // time is the delay in microsecns we wait in the mainloop until else if(steps == 80) time = del*2; // a micro step will be done else if(steps == 100) time = del-1; // cannot explain here is not del*1 if(steps == stepsMax-200) time = del*2; // stop ramp down (200 microsteps before end time will be increased else if(steps == stepsMax-80) time = del*3; else if(steps == stepsMax-40) time = del*4; else if(steps == stepsMax-20) time = del*5; ist[0] += dir[0]; // set new pos ist[1] += dir[1]; ist[2] += dir[2]; ist[3] += dir[3];
servo_0.writeMicroseconds(ist[3]); // Zange //anschlüsse gemappt! servo_1.writeMicroseconds(ist[2]); // Hand servo_2.writeMicroseconds(ist[0]); // Schulter servo_3.writeMicroseconds(ist[1]); // Ellbogen } else { Step = 1; // next step aus array lesen steps = 0; // servo zwischenschritte }
}
void data_out() // just to write the recorded data to serial
{ int i = 0; while(i < arrayMax) { digitalWrite(13, HIGH); i += 1; Serial.print(joint0[i]); Serial.print(", "); } Serial.println("Joint0"); i = 0; while(i < arrayMax) { digitalWrite(13, HIGH); i += 1; Serial.print(joint1[i]); Serial.print(", "); } Serial.println("Joint1"); i = 0; while(i < arrayMax) { digitalWrite(13, HIGH); i += 1; Serial.print(joint2[i]); Serial.print(", "); } Serial.println("Joint2"); i = 0; while(i < arrayMax) { digitalWrite(13, HIGH); i += 1; Serial.print(joint3[i]); Serial.print(", "); } Serial.println("Joint3");
}
void Button() // check buttons for single and doubleclick
{ if (digitalRead(6) == false) { delay(1); if (digitalRead(6) == true) // taster losgelassen { if (Taster == 0) { Taster = 1; previousMillis3 = currentMillis; //Serial.print("Status Record "); Serial.println(Taster); } else if ((Taster == 1) && (currentMillis - previousMillis3 < 250)) { Taster = 2; //Serial.println(Taster); } /*else if ((Taster == 2) && (currentMillis - previousMillis3 < 500)) { Taster = 3; Serial.println(Taster); }*/ } } if ((Taster == 1) && (currentMillis - previousMillis3 > 1000)) // write to array { arrayStep += 1; arrayMax = arrayStep; record(); Taster = 0; playmode = false; Serial.print("Record Step: "); Serial.println(arrayStep); digitalWrite(13, HIGH); delay(100); digitalWrite(13, LOW); } else if (Taster == 2) { arrayStep = 0; playmode = true; Taster = 0; Step = 1; Serial.println("playmode "); data_out(); delay(250); digitalWrite(13, LOW); } /*if (Taster == 3) { // ++ arrayStep // playmode = 1; Taster = 0; Serial.println("Clear "); }*/ if (currentMillis - previousMillis3 > 2000) // button Status clear { Taster = 0; //Serial.println("restart "); }
}
