Design of a Biped Actuated by Pleated Pneumatic Artificial Muscles

This paper presents the design of a biped actuated by Pleated Pneumatic Artificial Muscles. These actuators have a very high power to weight ratio and an inherent adaptable compliance. The mechanical design of the bipedal robot is modular, making parts easy to change and replace. The frame of the robot is made out of a high-grade aluminium alloy. The weight of the machine, all included, is about 30 kg and its height 150 cm. The applied control has two levels: a high level controller for the complete system and a low level controller for each joint, locally implementing the high level decisions. The high level controller runs on a PC and each low level controller is implemented on a 16-bit microcontroller and operates a set of fast switching pneumatic on-off valves that set the muscle pressures in order to follow required trajectories. All microcontrollers are linked to the PC through a dual ported ram unit that acts as a buffer and data transfer agent on a 16 bit parallel asynchronous bus. The paper discusses in detail the different concepts of our design. Special attention is given to the flexibility of the mechanical construction and the elaborate control hardware because through these an adaptable and broad experimental platform is ensured.