DocumentCode :
2093829
Title :
Torque and compliance control of the pneumatic artificial muscles in the biped "Lucy"
Author :
Vanderborght, Bram ; Verrelst, Björn ; Van Ham, Ronald ; Van Damme, Michaël ; Beyl, Pieter ; Lefeber, Dirk
Author_Institution :
Dept. of Mech. Eng., Vrije Univ., Brussels
fYear :
2006
fDate :
15-19 May 2006
Firstpage :
842
Lastpage :
847
Abstract :
In the biped Lucy pleated pneumatic artificial muscles are used instead of electrical motors to power the joints, because in an antagonistic set-up both the torque and the compliance are controllable. The muscles have also a high power to weight ratio and they can reduce impact effects. Interesting characteristics that can be exploited for legged robots. In this paper a control strategy is discussed where a torque control unit tracks a predefined trajectory and a compliance controller is used to reduce control efforts and energy consumption by fitting the compliance of the actuator to the natural compliance of the desired trajectory. The first part of this paper focusses on the torque control unit for the biped. The proposed control architecture consists of the joint trajectory generator and the joint trajectory tracking controller. The trajectory generator calculates trajectories represented by polynomials based on objective locomotion parameters, which are average forward speed, step length, step height and intermediate foot lift. The joint trajectory tracking controller is divided in three parts: a computed torque module, a delta-p unit and a bang-bang pressure controller. Results of the incorporation of this control architecture in the real biped Lucy are given. Several essential graphs showing tracking performance and pressure regulation are given and the effectiveness of the control algorithm is discussed. A second part of the paper focusses on the compliance controller which is experimentally tested on a one DOF pendulum. A mathematical formulation to exploit the natural dynamics with respect to different walking patterns for this purpose is explained. The experimental results show the effectiveness and importance of the adaptation strategy
Keywords :
artificial limbs; compliance control; force control; legged locomotion; pneumatic actuators; position control; torque control; bang-bang pressure controller; biped Lucy; compliance control; joint trajectory tracking controller; legged robots; pneumatic artificial muscles; torque control; Actuators; Computer architecture; Energy consumption; Foot; Legged locomotion; Muscles; Polynomials; Pressure control; Torque control; Trajectory;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Robotics and Automation, 2006. ICRA 2006. Proceedings 2006 IEEE International Conference on
Conference_Location :
Orlando, FL
ISSN :
1050-4729
Print_ISBN :
0-7803-9505-0
Type :
conf
DOI :
10.1109/ROBOT.2006.1641814
Filename :
1641814
Link To Document :
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