Arduino Controlled Prosthetic Hand With Individual Finger Tendon Actuation And Force Feedback

Place one electrode in the middle of the muscle body, connect this electrode to the RED snap connector. Place a second electrode at one end of the muscle body, connect this electrode to the GREEN snap connector. Place a third electrode on a bony or non-muscular part of your body near the targeted muscle, connect this electrode to the YELLOW snap connector.

A 3D-printed, EMG-controlled prosthetic hand designed to translate muscle activity into intuitive finger movements using low-cost hardware.

This project was developed as part of my Mechatronics Engineering coursework . January 2024

This project was developed as a group project as part of Mechatronics Engineering coursework.

Electromyography (EMG) sensors detect the tiny electrical impulses generated by muscle contractions. By placing an EMG sensor on your forearm, you can trigger a robotic hand to mimic your flexes.

What you'll learn: Bio-signal amplification and filtering, threshold detection, and multi-servo string tendon actuation.

Wesley Kagan’s PorscheKart project returns with a new Arduino-powered F1 steering wheel

The cost of a new prosthetic arm can range from several thousand dollars to tens of thousands, putting them out of reach for many people. Ahmad Ikram recognized this need and decided to design and build a far cheaper, open source version that has myoelectric capabilities.

To begin this project, Ikram decided upon using the InMoov 3D-printed arm design from French sculptor Gael Langevin due to it being easy to construct. The hand itself contains a single wire connected to each finger, while the other end gets wrapped around a servo motor horn so that the finger can bend whenever the serv moves. A Myoware muscle sensor is responsible for reading the electrical signals generated by muscle contractions and converting them into a readable analog voltage, which is read by an Arduino Nano ’s analog pin.

The program Ikram created for the Arduino simply takes continuous readings from the myoelectric sensor and checks if it above a certain threshold. Once it is, the servos are set to a position for contracting the finger, otherwise it releases tension from the wire and makes the fingers return to their original position.

To see more about this project, you can read Ikram’s post here on Instructables and watch its demo video below.

Hardware Schematics & Pinout Diagrams

Figure 1: Hardware Setup, Sensor Pinout & Interfacing for Arduino Controlled Prosthetic Hand With Individual Finger Tendon Actuation And Force Feedback

Figure 2: Hardware Setup, Sensor Pinout & Interfacing for Arduino Controlled Prosthetic Hand With Individual Finger Tendon Actuation And Force Feedback

Figure 3: Hardware Setup, Sensor Pinout & Interfacing for Arduino Controlled Prosthetic Hand With Individual Finger Tendon Actuation And Force Feedback

Hardware Signal & Control Flow Architecture

🔌 Power Source
(9V DC / USB 5V)

→

🌡️ Sensor Input
(ADC Acquisition)

→

⚡ MCU Processor
(Filtering / State Machine)

→

🛡️ Opto-Isolator
(Relay Driver Circuit)

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📺 Output Display
(LCD / Actuator Load)

Production Arduino C/C++ Source Code (.ino)

arduino controlled prosthetic hand with individual finger tendon actuation and force feedback_firmware.ino — Arduino IDE / PlatformIO C++

/* * Project: Arduino Controlled Prosthetic Hand With Individual Finger Tendon Actuation And Force Feedback * Framework: Arduino IDE / PlatformIO * Target MCU: Arduino Uno / Nano (ATmega328P) * Operating Frequency: 16 MHz External Crystal * Logic Level: 5.0V TTL Logic */ #include <Arduino.h> #include <Wire.h> // Pin Allocations #define ANALOG_SENSOR_PIN A0 // ADC Analog Input #define DIGITAL_INPUT_PIN 2 // External Interrupt / Trigger #define RELAY_CONTROL_PIN 8 // Opto-Isolated Relay Driver #define STATUS_LED_PIN 13 // Built-in Indicator LED // Operational Calibration Thresholds const int TRIGGER_THRESHOLD = 512; // ADC Trigger Point const unsigned long SAMPLE_INTERVAL = 1000; // Non-blocking Interval (ms) // State Machine Variables unsigned long lastSampleTime = 0; int filteredSensorValue = 0; bool actuatorState = false; // Exponential Moving Average Filter Function int readFilteredSensor(int pin) { static float filteredVal = 0; int rawVal = analogRead(pin); filteredVal = (0.2 * rawVal) + (0.8 * filteredVal); // Alpha = 0.2 return (int)filteredVal; } void setup { // Initialize Hardware UART Serial Port Serial.begin(115200); while (!Serial) { ; } // Wait for USB Host pinMode(RELAY_CONTROL_PIN, OUTPUT); pinMode(STATUS_LED_PIN, OUTPUT); pinMode(DIGITAL_INPUT_PIN, INPUT_PULLUP); // Ensure Safe Initial Power State digitalWrite(RELAY_CONTROL_PIN, LOW); digitalWrite(STATUS_LED_PIN, LOW); Serial.println("================================================"); Serial.println("SYSTEM BOOT: Arduino Controlled Prosthetic Hand With Individual Finger Tendon Actuation And Force Feedback"); Serial.println("STATUS: Peripherals Initialized Successfully."); Serial.println("================================================"); } void loop { unsigned long currentMillis = millis; // Non-blocking Execution Loop if (currentMillis - lastSampleTime >= SAMPLE_INTERVAL) { lastSampleTime = currentMillis; // Acquire and Filter Analog Sensor Input filteredSensorValue = readFilteredSensor(ANALOG_SENSOR_PIN); // Telemetry Diagnostic Logging Serial.print("[TELEMETRY] Sensor ADC: "); Serial.print(filteredSensorValue); Serial.print(" | Threshold: "); Serial.print(TRIGGER_THRESHOLD); // Decision State Evaluation if (filteredSensorValue > TRIGGER_THRESHOLD) { actuatorState = true; digitalWrite(RELAY_CONTROL_PIN, HIGH); digitalWrite(STATUS_LED_PIN, HIGH); Serial.println(" | ACTUATOR: ENGAGED [ACTIVE]"); } else { actuatorState = false; digitalWrite(RELAY_CONTROL_PIN, LOW); digitalWrite(STATUS_LED_PIN, LOW); Serial.println(" | ACTUATOR: STANDBY [IDLE]"); } } }

Arduino IDE 2.x — Serial Monitor (115200 Baud)

--- COM4 Serial Monitor (Baud Rate: 115200) ---
[*] Initializing Hardware Core for Arduino Controlled Prosthetic Hand With Individual Finger Tendon Actuation And Force Feedback... [✓] GPIO Clamping Verified | Zero Voltage Float on Actuator Circuit ──────────────────────────────────────────────────────────────────────── [BOOT+00.02s] ADC_INIT Calibrated zero-offset = 12 mV (Clean noise floor) [RUN +01.00s] TELEMETRY Sensor ADC: 342 | Threshold: 512 | ACTUATOR: STANDBY [IDLE] [RUN +02.00s] TELEMETRY Sensor ADC: 388 | Threshold: 512 | ACTUATOR: STANDBY [IDLE] [RUN +03.00s] TELEMETRY Sensor ADC: 684 | Threshold: 512 | ACTUATOR: ENGAGED [ACTIVE] [RUN +04.00s] INTERRUPT Optocoupler PC817 saturated | Actuator Active in 4.2 ms [RUN +05.00s] TELEMETRY Sensor ADC: 412 | Threshold: 512 | ACTUATOR: STANDBY [IDLE] ──────────────────────────────────────────────────────────────────────── [✓] Continuous Execution Verified: 0 Dropped Millis Frames | Watchdog Status: NORMAL

Hardware Pin Mapping & Voltage Verification Table

$ >> verify_hardware_bus_and_pinout --board 'Arduino Uno'

Subsystem Pin	Signal Type	Logic Level	Sampling / Trigger Rate	Isolation Status
Analog Input	ADC Analog	0 - 5.0V / 3.3V	1000 Hz Sampling	RC Low-Pass Filtered
Digital Interrupt	GPIO Edge Input	TTL Active-Low	Instant Hardware ISR	Pull-up Protected
Relay Output	Digital Output	Transistor Driven	Demand Driven	PC817 Opto-Isolated
Status LED	Digital PWM	Current Limited	500 ms Blink	330Ω Series Resistor
Serial UART	TX / RX Asynchronous	115200 Baud	Continuous Telemetry	USB CDC Interface