Model preview control in multi-contact motion-application to a humanoid robot

Abstract

Abstract-Our work builds largely on Nagasaka's stabilizer in multi-contact motion [1]. Using a sequence of contact stances from an offline multi-contact planner, we use first a Model Predictive Controller to generate a dynamic trajectory of the center of mass, then a whole-body closed-loop model-based controller to track it at best. Relatively to Nagasaka's work, we allow frame changes of the preferred force, provide a heuristic to compute the timing of the transition from purely geometrical features and investigate the synchronization problem between the reduced-model preview control and the whole-body controller. Using our framework, we generate a wide range of 3D motions, while accounting for predictable external forces, which includes transporting objects. Simulation scenarios are presented and obtained results are analyzed and discussed.

Vertical ladder climbing by the HRP-2 humanoid robot

“…For instance, by computing the CoM trajectory with a preview of up-coming contact, such as in [19]. This is certainly not necessary since the motion of the robot requires slow motion strategies at contact formation (including grasps) and removal and we do not use hook-like designed grippers.…”

Modelling of dynamically stable AR-601M robot locomotion in Simulink

“…A, B, C, D are the coefficients which are obtained from equation (8), and expansion of the state vector x in Taylor series to find its value in the next time [7]. In the role of a control vector u(k) the third derivative of the coordinates x, (݇) = ‫ݔ‬ ⃛(݇) is used.…”

“…Another approach (called the preview control approach) solves the bipedal walking as a ZMP tracking problem [7]. In this paper we overview two main walking pattern generation principles which are applied for Russian-made AR-601M anthropomorphic robot -a preview control method [8,9] and a virtual height inverted pendulum method [10,11]. Virtual experiments and control algorithms evaluation for AR-601M are performed in Simulink environment.…”

Model-predictive control in multi-contact based on stability polyhedrons

“…Typical MPC adopt an hierarchical approach, see e.g. in [1], [2], [3], [4]: they compute trajectories to be best tracked by the underlying local whole-body controller -see e.g. in [5], [6].…”

“…As it relied on the ZMP, it is however not applicable to multicontact motion. This approach was extended in [9] where Since then, we have proposed a multi-contact MPC formulation [2]. However, in order to linearize the CoM dynamics, we had to specify the motion along one axis, leave one component of the momentum uncontrolled and specify stance transition timings in a heuristic (non satisfactory) way.…”