Proportional Joint Moment Controller

Description

This controller applies a torque to the ankle proportional to the normalized FSR reading of the toe. More details on this controller can be found in:

G. M. Gasparri, J. Luque and Z. F. Lerner, “[Proportional Joint-Moment Control for Instantaneously Adaptive Ankle Exoskeleton Assistance](https://ieeexplore.ieee.org/abstract/document/8669971),” in IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 27, no. 4, pp. 751-759, April 2019, doi: 10.1109/TNSRE.2019.2905979.

Parameters

Parameter index order can be found in ControllerData.h.

  • stance_max The peak torque (in Nm) during stance. When the normalized FSR is 1, this will be the torque applied to the ankle.

  • swing_max The constant torque (in Nm) during swing. This value is rarely used.

  • is_assitance When set to 1 (assistive), the system applies the torque in the plantar flexion direction; when set to 0 (resistive), the torque is applied in the dorsiflexion direction.

  • use_pid This flag turns PID control on (1) or off (0).

  • p_gain Proportional gain for closed-loop control.

  • i_gain Integral gain for closed-loop control.

  • d_gain Derivative gain for closed-loop control.

  • torque_alpha Filtering term for the exponentially weighted moving average (EWMA) filter used on the torque sensor to reduce noise. Lower values increase the delay due to filtering.