Robot control
Whole-body control
Definition
Whole-body control coordinates a robot’s joints and contacts to satisfy several motion and force objectives together. In humanoids, it commonly combines balance, foot motion, hand tasks, and posture subject to physical constraints.
Also known as: WBC, Whole body control
Updated
Coordinating tasks that share joints
A humanoid reaching for a shelf cannot choose arm motion independently of balance and leg motion. Whole-body control expresses these requirements together, often assigning priorities or weights so that a hand task can yield when maintaining support requires it.
The survey by Wensing and colleagues describes widely used optimization formulations that compute joint commands from the current state. These can include contact constraints, joint limits, actuator effort limits, and desired task-space accelerations. Quadratic programs are common, but the term covers a broader family of control methods.
From a plan to motor commands
A higher-level planner may provide footsteps and a centroidal motion plan. The whole-body controller then uses the full robot model to realize those references through joint motion and contact forces. Operational-space control supplies a foundation for expressing task priorities, as described in MIT's manipulation notes.
Coordination cannot remove physical conflicts
If a hand target requires a joint to exceed its range while both feet remain fixed, all objectives cannot be satisfied exactly. The result depends on which constraints are hard and which goals are allowed error. Whole-body control also depends on the assumed contacts and estimated state; it does not itself guarantee that a planned foothold is present or that a slipping foot remains fixed.
Sources
Related terms
Operational-space control
Operational-space control formulates a robot’s motion and force behavior in task coordinates, such as the position and orientation of its hand, while accounting for the robot’s dynamics. Secondary joint objectives can be coordinated with the primary task.
Inverse dynamics
Inverse dynamics calculates the joint forces or torques required for specified joint positions, velocities, and accelerations under a dynamics model. The result also depends on gravity and specified external loading.
Centroidal dynamics
Centroidal dynamics describe the motion of a multibody system’s center of mass and the evolution of its total linear and angular momentum. External forces and moments determine the rates of change of those momenta.
Model predictive control
Model predictive control repeatedly optimizes future actions using a system model, applies the next part of the solution, and replans from updated state information. It can account for objectives and constraints over a finite prediction horizon.