Introduction: Wearable Assistive Tech Gripper: Doraemon's Hand

This project is done by a group of students from Singapore Polytechnic. We are: Yan Jun Feng, Yeo Ling Zhi Kenny, Chan Keng-Yew Paul,Cheong Kai Xiang, and our supervisor is: Mr. Teo Shin Jen.

The Concept of our prototype:

A wearable assistive technology device to help human with fore-arm disabilities or limited dexterity to pick up objects.

Skill level:

Basic soldering and C++ programming skill.

Things you need:

Ultrasonic sensor SRF05


Vacuum pump from aliexpress

Copper stripboard

Copper wire

Rainbow ribbon cable

12v dc relay

NPN transistor(2N2222) for the relay

12v 2800mAH Li-Ion battery

Step 1: Building the Coffee Gripper

Inspired by a DIY how to video we saw on the Internet

on the picking up mechanism, we have DIY the coffee gripper with the vacuum pump bought from aliexpress, hard tubing from local hardware store, balloon, and plastic bottle spout recycled from regular PET bottles. Used Coffee grounds courtesy of a local hotelier. Our version is extended with an ultrasonic sensor SRF05

Step 2: Wiring With the Pic18 Microcontroller

Input of micro controller: Ultrasonic sensor(2 data pins, vcc and gnd)

Output of micro controller: LED bar(8 data pins), vacuum pump(1 data pin)

Port B of micro controller connect to LED bar

Port D of micro controller connect to relay&transistor circuit that is used to switched 12v dc to the vacuum pump

Connection of ultrasonic sensor can be found here

wiring of the vacuum pump requires a standard 12v DC relay + 2N2222 transistor circuit with the base connected to MCU data pin.

Step 3: Ultrasonic Sensor & LED Bar

Construction of the sensor is as follow. Tape down the ultrasonic sensor at the side of the gripper.
The LED bar serves as an indicator to the distance reported by ultrasonic sensor

Step 4: Putting Everything Together

Using the rainbow ribbon cables, connect the MCU to the input and output devices. We have used a relay&transistor circuit to switched between 12v supply to the vacuum pump and 5v MCU data pins.

The electronics sans the coffee gripper&SRF05 are put into a pouch follow by the coffee gripper & SRF05 are assembled into a glove that is fastened with velcro. Airline tubin, VCC and gnd wires, data wires are then secure using heat shrink tubing and secure along the arm to the pouch.

Step 5: How It Works

The SRF05 will detect the distance between the gripper and the surface. Once the coffee gripper is placed upon the object to be picked up and the distance is within the threshold, the vacuum pump will start removing air from the balloon filled with coffee to create a grip surrounding the object.

Releasing of the object follows similar methodology.
Please see attached for source code.

Step 6: Demo Video

Tech Contest

Participated in the
Tech Contest

Epilog Challenge VI

Participated in the
Epilog Challenge VI