Zhang Collins Controller

Description

This controller applies a spline defined as a percent of gait. It requires a heel FSR for proper operation. The torque profile implemented by this controller is based on the following publication:

Zhang, J., Fiers, P., Witte, K. A., Jackson, R. W., Poggensee, K. L., Atkeson, C. G., & Collins, S. H. (2017). [Human-in-the-loop optimization of exoskeleton assistance during walking.](https://www.science.org/doi/full/10.1126/science.aal5054) Science, 356(6344), 1280-1284.

Parameters

Parameter index order can be found in ControllerData.h.

  • torque Magnitude of the peak torque in Nm.

  • peak_time Time when the peak torque occurs (expressed as a percentage of the gait cycle).

  • rise_time Duration from zero torque to peak torque (expressed as a percentage of the gait cycle).

  • fall_time Duration from peak torque back to zero torque (expressed as a percentage of the gait cycle).

  • direction Flag to flip the torque from plantarflexion (PF) to dorsiflexion (DF); essentially an assistance/resistance flag.

  • use_pid Flag to enable PID control (1 = on, 0 = off).

  • p_gain Proportional gain for closed-loop control.

  • i_gain Integral gain for closed-loop control.

  • d_gain Derivative gain for closed-loop control.