Hardware & control
Whole-body control
Whole-body control coordinates a humanoid’s full multibody state, actuated joints and environmental contacts to pursue several motion or force objectives while respecting constraints such as balance, joint limits and friction. It is a family of hierarchical or optimisation-based methods, not one algorithm; implementations may output joint positions, accelerations or torques.
Also known as: WBC, Whole body control
Updated
Why the whole body enters the problem
Moving one humanoid limb changes more than that limb’s pose. Reaching with a hand shifts momentum and balance, while feet, hands or knees may carry contact forces. The floating base is not directly actuated, so its motion must be influenced through joint torques and environmental contacts.
The Sentis and Khatib framework therefore models supporting contacts, operational tasks and residual posture together. Typical objectives include hand or foot motion, centre-of-mass behaviour, gaze and contact force, subject to structural and environmental constraints.
Hierarchies and optimisation are different implementations
Classical hierarchical control gives critical constraints higher priority, then projects lower-priority tasks into the remaining motion space. This can stop a posture objective from overriding balance or a contact condition. The original hierarchical whole-body formulation describes constraints, operational tasks and posture as distinct priority levels.
Optimisation-based controllers instead express dynamics, contacts, limits and tasks as equalities, inequalities and costs. Dynamic whole-body motion generation demonstrates a strict hierarchy with full multibody dynamics, while Task Space Inverse Dynamics treats prioritised motion and force control. Kinematic whole-body controllers may output positions or velocities; inverse-dynamics versions commonly output torque. “WBC” alone does not identify the interface.
What whole-body training data needs
A reference pose sequence is insufficient for contact-rich control. Useful records synchronise base state, joint state, task targets, contact schedule, contact wrench, controller priorities or weights, active constraints, model version and final commands.
Learned controllers also need a clear split between observations available on hardware and simulator-only privileged state. Preserving these details shows whether a policy learned coordinated physical control or merely reproduced kinematics with hidden information.
Sources
Related terms
Hardware & control
Degree of freedom
A degree of freedom (DoF) is one independent parameter needed to specify a robot’s configuration; equivalently, a robot’s DoF is the dimension of its configuration space. It describes possible motion, not the number of motors. Joint constraints, closed kinematic chains and environmental contacts can make joint count, actuator count and controllable motion differ.
Hardware & control
Proprioception
Proprioception is sensing of a robot’s own internal configuration and motion rather than the external scene. For a humanoid it commonly includes joint positions and velocities, actuator effort or torque, and inertial measurements of body rotation and acceleration. These signals support state estimation and feedback control but do not, by themselves, directly describe nearby objects or terrain.
Hardware & control
Torque control
Torque control is a control mode in which desired joint torques, or equivalent linear forces, are the command variables sent to a robot’s low-level actuators. Unlike position control, it does not directly command where each joint should be. Motion and contact instead emerge from the applied efforts, robot dynamics, feedback, constraints and any higher-level controller.
Hardware & control
Impedance control
Impedance control regulates the dynamic relationship between a robot’s motion error and the force or torque it exerts, usually by giving the robot virtual stiffness, damping and sometimes inertia. It lets an end effector or limb yield predictably during contact instead of trying to hold an exact position regardless of interaction forces.