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Flex Controlled Air Powered Gripper

Made by blight3d28 / 3D Printing / Robotics / Sensors / Wearables

About the project

A silicone air powered gripper controlled with a flex sensor glove.

Project info

Difficulty: Moderate

Platforms: Adafruit, Arduino, Seeed Studio

Estimated time: 6 hours

License: GNU General Public License, version 3 or later (GPL3+)

Items used in this project

Hardware components

	Seeed Studio Grove - 2-Channel SPDT Relay I used 7 individual relays.	x 3
	Adafruit nOOds- Flexible LED Filament	x 1
	coin cell holder	x 1
	Arduino Nano 33 BLE Sense	x 2
	Long flex sensor	x 1
	Ecoflex 00-30	x 1
	Adafruit Air tube	x 1
	Adafruit Air valve	x 3
	Adafruit Air pump	x 3

View all

Hand tools and fabrication machines

	3D Printer (generic)	x 1
	Soldering iron (generic)	x 1

Story

My project is a silicone gripper controlled with a flex sensor connected to my hand. When I close my hand the arduino nano 33 ble sense connected to the flex sensor sends a message to another nano 33 ble sense, the 2nd nano is connected to 7 relays. Each relay is connected to an air pump/valve (3 air pumps & 3 air valves), the final relay controls the nOOds green LED.

The silicone "fingers" are made of EcoFlex 00-30. I casted them using two 3D-printed molds, a top & bottom, which later is connected together using some eco-flex (also inserted an air tube in-between the two parts with a little bit of ecoflex to make sure it sticks).

Schematics, diagrams and documents

Transmitter _schematic

CAD, enclosures and custom parts

Base & top

Feed the air tubes through the holes & super glue the 3 fingers to each side. Super glue the top on the base.

Go to download

Glove_TPU

Glove made 3d printed out of tpu. Super glue flex sensor & electronics.

Go to download

Finger silicone molds

This makes the top & bottom of a silicone finger which you connect together with some silicone. The circular designs goes on the outside, the linear design goes on the inside.

Go to download

Code

Transmitter_BLE_Flex

The transmitter code, arduino nano 33 BE sense with a flex sensor sends msg via BLE to another arduino.

#include <ArduinoBLE.h> const int R_LED_PIN = 22; const int G_LED_PIN = 23; const int B_LED_PIN = 24; int voltageThreshold = 250; void setup() { Serial.begin(9600); // initialize the BLE hardware BLE.begin(); Serial.println("BLE Central - LED control"); // start scanning for peripherals BLE.scanForUuid("19b10000-e8f2-537e-4f6c-d104768a1214"); } void loop() { // check if a peripheral has been discovered BLEDevice peripheral = BLE.available(); if (peripheral) { // discovered a peripheral, print out address, local name, and advertised service Serial.print("Found "); Serial.print(peripheral.address()); Serial.print(" '"); Serial.print(peripheral.localName()); Serial.print("' "); Serial.print(peripheral.advertisedServiceUuid()); Serial.println(); if (peripheral.localName() != "LED") { return; } // stop scanning BLE.stopScan(); controlLed(peripheral); // peripheral disconnected, start scanning again BLE.scanForUuid("19b10000-e8f2-537e-4f6c-d104768a1214"); } } void controlLed(BLEDevice peripheral) { Serial.println("Connecting ..."); if (peripheral.connect()) { Serial.println("Connected"); } else { Serial.println("Failed to connect!"); return; } // discover peripheral attributes Serial.println("Discovering attributes ..."); if (peripheral.discoverAttributes()) { Serial.println("Attributes discovered"); } else { Serial.println("Attribute discovery failed!"); peripheral.disconnect(); return; } // retrieve the LED characteristic BLECharacteristic ledCharacteristic = peripheral.characteristic("19b10001-e8f2-537e-4f6c-d104768a1214"); if (!ledCharacteristic) { Serial.println("Peripheral does not have LED characteristic!"); peripheral.disconnect(); return; } else if (!ledCharacteristic.canWrite()) { Serial.println("Peripheral does not have a writable LED characteristic!"); peripheral.disconnect(); return; } while (peripheral.connected()) { int currentVoltage = analogRead(A0); // store the incoming voltage Serial.println(currentVoltage); if (currentVoltage < 200 ) { setColor("GREEN"); ledCharacteristic.writeValue((byte)0x01); } if (currentVoltage > voltageThreshold) { Serial.println("button released"); setColor("RED"); ledCharacteristic.writeValue((byte)0x00); } } Serial.println("Peripheral disconnected"); } void setColor(String color) { if (color == "RED") { digitalWrite(R_LED_PIN, LOW); // High values -> lower brightness digitalWrite(G_LED_PIN, HIGH); digitalWrite(B_LED_PIN, HIGH); }else if (color == "GREEN") { digitalWrite(R_LED_PIN, HIGH); // High values -> lower brightness digitalWrite(G_LED_PIN, LOW); digitalWrite(B_LED_PIN, HIGH); }else if (color == "BLUE") { digitalWrite(R_LED_PIN, HIGH); // High values -> lower brightness digitalWrite(G_LED_PIN, HIGH); digitalWrite(B_LED_PIN, LOW); }else if (color == "PURPLE") { digitalWrite(R_LED_PIN, LOW); // High values -> lower brightness digitalWrite(G_LED_PIN, HIGH); digitalWrite(B_LED_PIN, LOW); } }

Receiver_BLE_Flex

Receiver code, controls the relays connected to the 3 air pumps/3 air valves plus the nOOds LED.

#include <ArduinoBLE.h> BLEService ledService("19B10000-E8F2-537E-4F6C-D104768A1214"); // BLE LED Service // BLE LED Switch Characteristic - custom 128-bit UUID, read and writable by central BLEByteCharacteristic switchCharacteristic("19B10001-E8F2-537E-4F6C-D104768A1214", BLERead | BLEWrite); int relay7SOLELEFT = 7; int relay10PUMPLEFT = 10; int relay8SOLEMIDDLE = 8; int relay11PUMPMIDDLE = 11; int relay9SOLERIGHT = 9; int relay12PUMPRIGHT = 12; int relay5LED = 5; void setup() { Serial.begin(9600); pinMode(relay7SOLELEFT, OUTPUT); pinMode(relay10PUMPLEFT, OUTPUT); pinMode(relay8SOLEMIDDLE, OUTPUT); pinMode(relay11PUMPMIDDLE, OUTPUT); pinMode(relay9SOLERIGHT, OUTPUT); pinMode(relay12PUMPRIGHT, OUTPUT); pinMode(relay5LED, OUTPUT); // begin initialization if (!BLE.begin()) { Serial.println("starting BLE failed!"); while (1); } // set advertised local name and service UUID: BLE.setLocalName("LED"); BLE.setAdvertisedService(ledService); // add the characteristic to the service ledService.addCharacteristic(switchCharacteristic); // add service BLE.addService(ledService); // set the initial value for the characeristic: switchCharacteristic.writeValue(0); // start advertising BLE.advertise(); Serial.println("BLE LED Peripheral"); } void loop() { // listen for BLE peripherals to connect: BLEDevice central = BLE.central(); // if a central is connected to peripheral: if (central) { Serial.print("Connected to central: "); // print the central's MAC address: Serial.println(central.address()); // while the central is still connected to peripheral: while (central.connected()) { // if the remote device wrote to the characteristic, // use the value to control the LED: if (switchCharacteristic.written()) { if (switchCharacteristic.value()) { // any value other than 0 digitalWrite(relay8SOLEMIDDLE, HIGH); digitalWrite(relay11PUMPMIDDLE, HIGH); digitalWrite(relay7SOLELEFT, HIGH); digitalWrite(relay10PUMPLEFT, HIGH); digitalWrite(relay9SOLERIGHT, HIGH); digitalWrite(relay12PUMPRIGHT, HIGH); digitalWrite(relay5LED, HIGH); Serial.println("ON"); } else { // a 0 value digitalWrite(relay8SOLEMIDDLE, LOW); digitalWrite(relay11PUMPMIDDLE, LOW); digitalWrite(relay7SOLELEFT, LOW); digitalWrite(relay10PUMPLEFT, LOW); digitalWrite(relay9SOLERIGHT, LOW); digitalWrite(relay12PUMPRIGHT, LOW); digitalWrite(relay5LED, LOW); Serial.println("OFF"); } } } } }

Credits

blight3d28

Hi, I'm Computer Scientist, love robotics & programming.

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About the project

Project info