  Pneumatic muscle actuators (PMA) are easy-to-fabricate, lightweight,
compliant, and have high power-to-weight ratio, thus making them the ideal
actuation choice for many soft and continuum robots. But so far, limited work
has been carried out in dynamic control of PMAs. One reason is that PMAs are
highly hysteretic. Coupled with their high compliance and response lag, PMAs
are challenging to control, particularly when subjected to external loads. The
hysteresis models proposed to-date rely on many physical and mechanical
parameters that are difficult to measure reliably and therefore of limited use
for implementing dynamic control. In this work, we employ a Bouc-Wen hysteresis
modeling approach to account for the hysteresis of PMAs and use the model for
implementing dynamic control. The controller is then compared to PID feedback
control for a number of dynamic position tracking tests. The dynamic control
based on the Bouc-Wen hysteresis model shows significantly better tracking
performance. This work lays the foundation towards implementing dynamic control
for PMA-powered high degrees of freedom soft and continuum robots.
