Partial Force Control of Constrained Floating-Base Robots
This addresses control challenges for legged robots in complex environments, offering an incremental improvement in computational efficiency and performance.
The paper tackles the problem of controlling motion and contact forces for legged robots in multi-contact scenarios, presenting a method that reduces computational complexity while preserving flexibility, validated through simulations on a 23-degree-of-freedom humanoid robot and showing benefits like eliminating force/torque discontinuities compared to state-of-the-art techniques.
Legged robots are typically in rigid contact with the environment at multiple locations, which add a degree of complexity to their control. We present a method to control the motion and a subset of the contact forces of a floating-base robot. We derive a new formulation of the lexicographic optimization problem typically arising in multitask motion/force control frameworks. The structure of the constraints of the problem (i.e. the dynamics of the robot) allows us to find a sparse analytical solution. This leads to an equivalent optimization with reduced computational complexity, comparable to inverse-dynamics based approaches. At the same time, our method preserves the flexibility of optimization based control frameworks. Simulations were carried out to achieve different multi-contact behaviors on a 23-degree-offreedom humanoid robot, validating the presented approach. A comparison with another state-of-the-art control technique with similar computational complexity shows the benefits of our controller, which can eliminate force/torque discontinuities.