Momentum-centric whole-body control and kino-dynamic motion generation for floating-base robots

Speaker: Alexander Herzog , Max Planck Institute for Intelligent Systems

Date: Tuesday, November 29, 2016

Time: 11:00 AM to 12:00 PM Note: all times are in the Eastern Time Zone

Public: Yes

Location: 32-G449 (Patil/Kiva)

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Host: Russ Tedrake, CSAIL

Contact: Russ Tedrake, russt@csail.mit.edu

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Reminders to: robotics@mit.edu, seminars@csail.mit.edu

Reminder Subject: TALK: Momentum-centric whole-body control and kino-dynamic motion generation for floating-base robots

Humanoid robots with torque control capabilities are becoming increasingly available in our research community. These robots allow for an explicit control of contact interactions which have the potential to allow robots locomote through difficult terrains. In order to accomplish tasks under balance and contact constraints, whole-body planning and control strategies are required to generate motion and force commands for all limbs efficiently.

Model-based control in combination with numerical optimization is becoming a reliable tool for efficient control of complex tasks on floating-base robots. In the first part of my talk I will discuss hierarchical inverse dynamics, a control framework that allows for the composition of complex behaviors from a hierarchy of simpler tasks and constraints. We use cascades of quadratic programs to resolve task hierarchies into joint torques in a 1kHz feedback-loop on our torque controlled humanoid. In our experiments we control the momentum of the robot embedded into a hierarchy of tasks and constraints leading to robust push recovery on our robot.

In the second part of my talk I will discuss our kino-dynamic motion generation approach for the full body. We solve an optimization program to obtain whole-body joint and contact force trajectories over a horizon that consider the full robot dynamics and contact constraints. We decompose this non-convex optimization problem into two better structured mathematical programs that are solved iteratively with better informed solvers. Our analysis reveals structure in the centroidal momentum dynamics of floating-base robots that leads to new efficient solvers on the full humanoid model. We can improve the speed of naive off-the shelf solvers by an order of magnitude and phrase direct shooting methods on centroidal dynamics with linear time complexity.

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Created by Russ Tedrake at Saturday, November 26, 2016 at 1:52 PM.