FSRray

E-Skin

A bioinspired electronic skin system for robotic applications, combining FSR (force-sensing resistor) arrays and accelerometer arrays.

Overview

The electronic board uses two multiplexers and two 16-channel ADCs to read the FSRs. The multiplexers select the row or column of the FSR array, while the ADCs read the sensor values. A Teensy 4.1 controls the multiplexers and ADCs and sends data to the computer via USB or Ethernet.

Operation modes:

• Single mode: Connect one FSR array with up to 32x32 sensors
• Dual mode: Connect two FSR arrays with up to 16x16 sensors each

Sampling rate: ~400 KHz/channel (1562.5 Hz for a 16x16 array)

Project Structure

e-skin/
├── host/           # C++/Qt host application
│   ├── src/        # Source code (main.cpp)
│   └── lib/        # Git submodules (com_client, built_lsl)
├── src/            # Teensy firmware
│   └── Eskin/      # Main production firmware
├── models/         # KiCAD PCB designs
│   ├── KiCAD/              # Main control board (MUX + ADC)
│   ├── customSquare16x16/  # 16x16 FSR array
│   ├── customSquare8x8/    # 8x8 FSR array
│   ├── LIS2DH_array/       # LIS2DH accelerometer array
│   ├── KX134_array/        # KX134 accelerometer array
│   └── inskinacc/          # In-skin accelerometer
└── script/         # Python/MATLAB data acquisition scripts

Requirements

Host Application

• CMake 3.3+
• Qt6 (Core, Widgets, PrintSupport)
• C++11 compiler

Firmware

• Arduino IDE or PlatformIO
• Teensy 4.1 board support

Python Scripts

• Python 3.x
• Dependencies: pip install -r script/requirements.txt

Building

Host Application

cd host
mkdir build && cd build
cmake .. && make
./FSR_array -h  # Show usage

Firmware

Upload src/Eskin/Eskin.ino to Teensy 4.1 using Arduino IDE or PlatformIO.

• Board: Teensy 4.1
• Port: /dev/ttyACM0 (Linux) or COMx (Windows)

Python Data Recorder

pip install -r script/requirements.txt
python script/record.py <port> <array_size>
# Example: python script/record.py /dev/ttyACM0 16

Communication Protocol

• Serial: 500000 baud
• Ethernet: TCP port 5000
• Command format: 1 byte (2 MSB = mode, 6 LSB = array size)
  • Mode 0: Request 1 FSR array
  • Mode 1: Request 2 FSR arrays
  • Mode 2: Request 1 ACC array
  • Mode 3: Request 1 ACC array + 2 FSR arrays
• Response: 4-byte timestamps + uint16_t sensor data

Submodule Dependencies

• built_lsl - Lab Streaming Layer integration
• com_client - Serial/TCP communication library

Initialize submodules:

git submodule update --init --recursive

Example

See main.cpp for an example of how to use the communication library.

Contributing

See CONTRIBUTING.md for details on our code of conduct and the process for submitting pull requests.