Sensing

Micron 2 Sensing

The sensing system of Micron 2 is a magnetometer aided gyroscope-free inertial measurement unit (GS-IMU), it consists of:

·        Three dual-axis accelerometers – Analog Devices ADXL-202E or ADXL-203

·        Three-axis magnetometer – Honeywell HMC-2003

Comparing with a conventional three gyros and three accelerometers IMU of Micron 1, the new all-accelerometers design reduces the standard deviation of the estimates of translational displacements by 29.3% in each principal axis and those of the Euler orientation parameters q_x, q_y and q_z by 99.1%, 99.1% and 92.8% respectively. Technical details of Micron 2 Sensing system:

·       Design of All-Accelerometer Inertial Measurement Unit for Tremor Sensing in Hand-held Microsurgical Instrument

      W. Ang, P. Khosla and C. Riviere

      IEEE International Conference on Robotics and Automation, Sep 2003

A detailed modeling error analysis is performed on the magnetometer aided GS-IMU. The measurement model is summarized as shown:

The North-sensing information of the magnetometer and the gravity information of accelerometers are fused via Extended Kalman filtering to bind the orientation or attitude errors caused by the integration drifts of the inertial sensors.

Half-Micron Video