Design and Control of a Pneumatic Hybrid Actuator

To simulate arbitrary force/displacement relationships, a hybrid actuator consisting of a .uidic muscle and a linear pressure spring is presented. Fluidic Muscles are interesting in their use as actuators in robotics, since they have a high power/weight ratio, a slip-stick free motion and a long durability. The operating point is de.ned as the half contracted-stroke of the muscle. The present paper describes a procedure to simulate virtual stiffness of a linear actuator by choosing an operating point of the pre-stressed muscle and applying PID Control to produce desired forces as function of state. The results are presented for a testbed. It is shown how the aforementioned control scheme produces a rapid and .exible stiffnes simulation. The device can be employed for later use in general environments such as motion simulations. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)