Planning robust walking motion on uneven terrain via convex optimization
In this paper, we present a convex optimization problem to generate Center of Mass (CoM) and momentum trajectories of a walking robot, such that the motion robustly satisfies the friction cone constraints on uneven terrain. We adopt the Contact Wrench Cone (CWC) criterion to measure a robot's d...
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| Format: | Article |
| Language: | English |
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IEEE
2020
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| Online Access: | https://hdl.handle.net/1721.1/124923 |
| _version_ | 1826189651104235520 |
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| author | Dai, Hongkai Tedrake, Russell L |
| author2 | Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory |
| author_facet | Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory Dai, Hongkai Tedrake, Russell L |
| author_sort | Dai, Hongkai |
| collection | MIT |
| description | In this paper, we present a convex optimization problem to generate Center of Mass (CoM) and momentum trajectories of a walking robot, such that the motion robustly satisfies the friction cone constraints on uneven terrain. We adopt the Contact Wrench Cone (CWC) criterion to measure a robot's dynamical stability, which generalizes the venerable Zero Moment Point (ZMP) criterion. Unlike the ZMP criterion, which is ideal for walking on flat ground with unbounded tangential friction forces, the CWC criterion incorporates non-coplanar contacts with friction cone constraints. We measure the robustness of the motion using the margin in the Contact Wrench Cone at each time instance, which quantifies the capability of the robot to instantaneously resist external force/torque disturbance, without causing the foot to tip over or slide. For pre-specified footstep location and time, we formulate a convex optimization problem to search for robot linear and angular momenta that satisfy the CWC criterion. We aim to maximize the CWC margin to improve the robustness of the motion, and minimize the centroidal angular momentum (angular momentum about CoM) to make the motion natural. Instead of directly minimizing the non-convex centroidal angular momentum, we resort to minimizing a convex upper bound. We show that our CWC planner can generate motion similar to the result of the ZMP planner on flat ground with sufficient friction. Moreover, on an uneven terrain course with friction cone constraints, our CWC planner can still find feasible motion, while the outcome of the ZMP planner violates the friction limit. Keywords: Friction; Robustness; Legged locomotion; Robot kinematics; Foot; Convex functions |
| first_indexed | 2024-09-23T08:19:00Z |
| format | Article |
| id | mit-1721.1/124923 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:19:00Z |
| publishDate | 2020 |
| publisher | IEEE |
| record_format | dspace |
| spelling | mit-1721.1/1249232022-09-23T12:18:21Z Planning robust walking motion on uneven terrain via convex optimization Dai, Hongkai Tedrake, Russell L Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory In this paper, we present a convex optimization problem to generate Center of Mass (CoM) and momentum trajectories of a walking robot, such that the motion robustly satisfies the friction cone constraints on uneven terrain. We adopt the Contact Wrench Cone (CWC) criterion to measure a robot's dynamical stability, which generalizes the venerable Zero Moment Point (ZMP) criterion. Unlike the ZMP criterion, which is ideal for walking on flat ground with unbounded tangential friction forces, the CWC criterion incorporates non-coplanar contacts with friction cone constraints. We measure the robustness of the motion using the margin in the Contact Wrench Cone at each time instance, which quantifies the capability of the robot to instantaneously resist external force/torque disturbance, without causing the foot to tip over or slide. For pre-specified footstep location and time, we formulate a convex optimization problem to search for robot linear and angular momenta that satisfy the CWC criterion. We aim to maximize the CWC margin to improve the robustness of the motion, and minimize the centroidal angular momentum (angular momentum about CoM) to make the motion natural. Instead of directly minimizing the non-convex centroidal angular momentum, we resort to minimizing a convex upper bound. We show that our CWC planner can generate motion similar to the result of the ZMP planner on flat ground with sufficient friction. Moreover, on an uneven terrain course with friction cone constraints, our CWC planner can still find feasible motion, while the outcome of the ZMP planner violates the friction limit. Keywords: Friction; Robustness; Legged locomotion; Robot kinematics; Foot; Convex functions Navy - ONR / Fy AppropriationsUncapped Funds (6923036) 2020-04-29T14:52:13Z 2020-04-29T14:52:13Z 2017-01 2019-07-11T13:08:47Z Article http://purl.org/eprint/type/ConferencePaper 9781509047185 2164-0580 9781509047178 https://hdl.handle.net/1721.1/124923 Dai, Hongkai and Tedrake, Russ. "Planning robust walking motion on uneven terrain via convex optimization." IEEE-RAS 16th International Conference on Humanoid Robots (Humanoids), November 2016, Cancun, Mexico, edited by Tamim Asfour, et al. IEEE, 2017 en http://dx.doi.org/10.1109/humanoids.2016.7803333 IEEE-RAS 16th International Conference on Humanoid Robots (Humanoids) Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf IEEE Other repository |
| spellingShingle | Dai, Hongkai Tedrake, Russell L Planning robust walking motion on uneven terrain via convex optimization |
| title | Planning robust walking motion on uneven terrain via convex optimization |
| title_full | Planning robust walking motion on uneven terrain via convex optimization |
| title_fullStr | Planning robust walking motion on uneven terrain via convex optimization |
| title_full_unstemmed | Planning robust walking motion on uneven terrain via convex optimization |
| title_short | Planning robust walking motion on uneven terrain via convex optimization |
| title_sort | planning robust walking motion on uneven terrain via convex optimization |
| url | https://hdl.handle.net/1721.1/124923 |
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