DIY Simple Robot Claw/Gripper (Actuated)

This is a simple actuated robot claw made out of household materials such as popsicle sticks and cardboard. It is designed as a quick and easy projects for aspiring makers and DIYers.

This robot claw is actuated with a single 9g servo motor, whose movement is controlled by a push button switch. Holding the switch button will make the robot claw grip, and it is released when the maximum threshold angle of the gripper has been reached.

I am inspired to make this robot claw and share this design with other makers as I found that a large majority of the robot claws designs requires a lot of expensive materials or sophisticated tools like laser cutters and 3D printers. This design merely requires cardboard, popsicle sticks, and a hot glue gun, all of which can be acquired form the local dollar store.

Step 1: Tools and Materials

Materials

• Popsicle Sticks
• Cardboard

Electronics

• Breadboard
• Push Button Switch
• 10K Ω Resistor
• Arduino 101 or Arduino Uno
• Jumper Wires
• Servo motor
• Servo Extension

Tools

• Scissors
• Hot glue gun and glue sticks
• Tape

Step 2: Making the Claws

1. Cut 1/3 of the popsicles stick off using a pair of scissors.
2. Glue these pieces back at a 20 degree angle with a hot glue gun
3. Further secure it by wrapping with clear tape around the glued area, once dried.
4. Tape two pairs of these popsicle claws together to provide strength, then apply small bead of hot glue in the middle.
5. Repeat these steps until you have 3 pairs of claws

Step 3: Glueing the Cardboard to the Bottom Claw

1. Cut a rectangular piece of cardboard the length of the claw and 4.5cm wide.
2. Glue the popsicle claws on the edges of the cardboard cut-out.
3. Make a half-box with the cardboard, like shown in the picture, and glue it to the popsicle claw with hot glue.
4. Cut off any excess cardboard.

Step 4: Glueing the Cardboard to the Top Claw

1. Cut off a 4.5 x 4.5cm square piece of cardboard and bend it 90 degrees at the midpoint
2. Add a bead of glue at the bend and spread it to make the 90 degree bend permanent
3. Cut off a notch the size of two possible sticks at the centre of the 90 degree bend.
4. Stick the popsicle sticks through the notch and glue it down.

Step 5: Calibrating and Gluing the Servo Motor

1. Glue the base of the servo horizontally to the top claw's cardboard base.
2. Plug in the red wire of the servo motor to the 5V pin in the Arduino Board
3. Plug in the black wire of the servo motor to the GND pin in the Arduino Board.
4. Plug in the white wire of the servo motor to the digital pin 3 in the Arduino Board.
5. Then compile and upload the code below to calibrate the servo motor

#include <Servo.h>

Servo servo1;

int servoPin = 3;

void setup() {
  // initialize servo motor

  servo1.attach (servoPin);
  servo1.write(0);

}

5. At this calibrated position of the servo, apply hot glue to the control horn and glue it to bottom claw horizontally.

6. Unplug the wires once glued.

7. [Optional] Cut off a notch if the servo's body hits the bottom cardboard.

Step 6: Wiring the Circuit

1. Connect the servo extension cable to the servo motor wire. Be mindful of the connections, the colours must match.
2. Connect the signal wire of the servo extension, shown as the blue jumper wire, to pin 3 in the Arduino Board.
3. Connect the red wire of the servo extension, shown as the red jumper wire, to the 5V pin in the Arduino Board.
4. Connect the black wire of the servo extension, shown as the black jumper wire, to the GND pin in the Arduino
5. Connect one of the pins of the switch to a 10KΩ resistor to the red power rail in the breadboard. Connect this same pin to pin 7 on the Arduino, as well.
6. Connect the other remaining pin of the switch to a the GND pin on the Arduino Board..
7. Lastly, connect the red power rail in the breadboard to the 3.3V pin on the Arduino Board.

Step 7: Coding

The servo motor is controlled by pushing the push button switch, read as a 0, since it is an active low signal. When the push button is released, the servo holds it position. This is evident in the code, as the switch is used as a toggle switch. When the servo reaches it maximum gripping angle, then the object is released the it is actuated back to it's initial position, which we have calibrated to be 0 degrees.

#include Servo servo1;int servoPin = 3;
int switchPin = 7;
int counter = 0;void setup() {
  // put your setup code here, to run once:  // initialize servo motor
  servo1.attach (servoPin);
  
  // declare the switch pin as an input signal
  pinMode (switchPin, INPUT); 
  servo1.write(80);
  Serial.begin (9600);
}
void loop() {
  // put your main code here, to run repeatedly:    int buttonState = digitalRead (switchPin);
  Serial.println(buttonState);
  if (buttonState == 0){
    if (counter != 90){
    //servo1.write (counter);
    counter++;  
    } else {
    //servo1.write (0);
    counter = 0;
    }
  }
  delay(10);
  
}

Step 8: Robot Claw Demonstration

The robot claw can hold light objects such as this shot glass, where I store all my jumper wires. It's strength is determined by the torque that your servo motor can provide.

Enjoy your build, make it your own, and keep on making awesome projects!