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FlexSEA-Pocket 0.1

FlexSEA-Pocket is a a low-power, 2-DoF version of FlexSEA-Rigid that was designed for the MIT Media Lab Biomechatronics group. It powers the climbing prosthesis demonstrated in Hugh Herr's 2018 TED talk: "How we'll become cyborgs and extend human potential".


  • Motors:
    • Motor 1 is connected to the phases marked 1 (positive) and 2 (negative)
    • Motor 2 is connected to the phases marked 3 (positive) and 4 (negative)
  • Encoders:
    • Quadrature encoder 1 is connected to +5V and GND, as well as IO4 (A) an IO5 (B)
    • Quadrature encoder 2 is connected to +5V and GND, as well as IO0 (A) an IO1 (B)
  • Strain gauges:
    • Strain gauge 1 is connected to +5V and GND, as well as SG1_P (Green) and SG1_N (White)
    • Strain gauge 2 is connected to +5V and GND, as well as SG2_P (Green) and SG2_N (White)
    • If the strain gauge has a shield, connect it to GND on one end of the cable.
  • General:
    • It is recommended to use one pair of power pins for the two encoders, and one for the two strain gauges. This will leave power pins available for future additions.

All the J10 signals are linked to Manage. All the signals use 3V3 logic, not 5V.

  • Communication:
    • UART2 RX and TX
    • SPI4, full-duplex interface with one slave select line
    • RS-485
  • 2x analog inputs, 0-3V3 12-bits. The signals are buffered (G=1) with an MCP6002.
  • 4x +3V3, 4x GND


Software Configuration

This information is as of 03/02/2018. This is a preliminary release, expect changes.

  • Open controller: range is ±500. It's a PWM duty cycle, not a voltage.

Known bugs

  • AIN0 and AIN1 are swapped on the schematic. Use analog[0] to read AIN1, and vice-versa.
flexsea-pocket.txt · Last modified: 2019/01/14 21:23 (external edit)