Paper Info
Title
Full dynamics LQR control of a humanoid robot: An experimental study on balancing and squatting
Abstract
Humanoid robots operating in human environments require whole-body controllers that can offer precise tracking and well-defined disturbance rejection behavior. In this contribution, we propose an experimental evaluation of a linear quadratic regulator (LQR) using a linearization of the full robot dynamics together with the contact constraints. The advantage of the controller is that it explicitly takes into account the coupling between the different joints to create optimal feedback controllers for whole-body control. We also propose a method to explicitly regulate other tasks of interest, such as the regulation of the center of mass of the robot or its angular momentum. In order to evaluate the performance of linear optimal control designs in a real-world scenario (model uncertainty, sensor noise, imperfect state estimation, etc), we test the controllers in a variety of tracking and balancing experiments on a torque controlled humanoid (e.g. balancing, split plane balancing, squatting, pushes while squatting, and balancing on a wheeled platform). The proposed control framework shows a reliable push recovery behavior competitive with more sophisticated balance controllers, rejecting impulses up to 11.7 Ns with peak forces of 650 N, with the added advantage of great computational simplicity. Furthermore, the controller is able to track squatting trajectories up to 1 Hz without relinearization, suggesting that the linearized dynamics is sufficient for significant ranges of motion.
Year
DOI
Venue
2014
10.1109/HUMANOIDS.2014.7041387
Humanoid Robots
Keywords
Field
DocType
angular momentum,controllers,feedback,humanoid robots,linear quadratic control,mobile robots,motion control,position control,robot dynamics,stability,torque control,angular momentum,balance controllers,balancing experiments,contact constraints,disturbance rejection behavior,full dynamics LQR control,human environments,humanoid robot,impulse rejection,linear quadratic regulator,linearized dynamics,optimal feedback controllers,precise tracking,push recovery behavior,squatting trajectory tracking,torque controlled humanoid,whole-body controllers
Robot control,Control theory,Torque,Optimal control,Control theory,Simulation,Computer science,Robot,Linear-quadratic regulator,Linearization,Humanoid robot
Conference
ISSN
Citations 
PageRank 
2164-0572
5
0.55
References 
Authors
13
3
Name
Order
Citations
PageRank
Sean Mason1493.55
Ludovic Righetti271154.91
Stefan Schaal36081530.10