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hardware:mocap

Board overview

This board is designed for motion capture. It especially targets human motion.

Technology used

For accurate motion reconstruction accelerometer is not sufficient on its own. For example, a rotation along an axis that does not cross the accelerometer center can generate a huge acceleration (Coriolis acceleration). To compensate this artifact, one must use a sensor that gives a hint on the rotation. On the motion board we propose on this website, we added two kind of sensors: gyrometer and magnetometer. The accelerometer we used is a LIS3LV02DQ from ST Microelectronics. Its a 3-axis 12-bits-resolution accelerometer (+/-6g) that is interfaced using I2C or SPI buses. For rotation estimation we added two gyrometers, a single-axis gyrometer and a dual-axis one (because 3-axis gyrometers do not exists at the time we speak). The single-axis one is a LY530AL from ST Microelectronics (Z axis, 10-bits resolution, I2C, SPI and analog outputs, +/-300°/s). The dual-axis X-Y gyrometer is a IDG500 from Invensense (analog output, +/-500°/s). For more accurate orientation estimation we added a I2C 3-axis magnetometer from Honeywell (HMC5843) that gives 12-bits measures of the magnetic field (earth magnetic field for angular reference).

Interface with WSN430 boards

As the four sensors we used on this board have different kind of interface, we chose to connect them that way:

  • LIS3LV02DQ is connected to the I2C bus (SPI was not chosen because the magnetometer has only I2C)
  • LY530AL is also connected to the I2C bus
  • IDG500 is connected the ADCs
  • HMC5843 is connected to I2C bus

The daughter board pinout is:

  • I2C:
    • SDA: SERIAL_IN
    • SCL: SERIAL_CLK
  • ADC
    • X: ADC1
    • X4.5: ADC0
    • Y: ADC4
    • Y4.5: ADC3
    • IDG500 voltage reference: DAC0 (ADC6)
    • Temperature sensor: DAC1 (ADC7)

Board schematics

Main schematic

Power supply

Accelerometer

Gyrometers

Dual-axis (X-Y) gyrometer

Single-axis (Z) gyrometer

Magnetometer

hardware/mocap.txt · Last modified: 2018/04/13 14:47 (external edit)