Balancing of Humanoid with Object Mass: Trade-off Analyses and Lifting Control

Noosaga Placements

• Robot Controlsubfield90%
  The paper focuses on balance control and trajectory optimization for humanoid robots, directly addressing robot control methodologies.
  The dynamic models and constraints are incorporated into the construction of the balanced state basin/boundary (BSB)...sufficient conditions for imposing balanced states on a trajectory are established and implemented with BSBs as explicit threshold constraints in the whole-body trajectory optimization for stable object-lifting control
• Operational-Space and Task-Space Controlframework80%
  The paper uses whole-body trajectory optimization and control, which aligns with operational-space and task-space control frameworks.
  implemented with BSBs as explicit threshold constraints in the whole-body trajectory optimization for stable object-lifting control
• Robot Kinematics Dynamicssubfield85%
  The paper heavily relies on whole-body dynamics, centroidal momentum, and contact wrench formulations, which are core to robot kinematics and dynamics.
  By formulating the object mass parameters in the whole-body dynamics with distributed contact wrenches and centers of pressure at the stance contacts...The joint-space dynamics are used to model the joint kinematics and actuations, the Cartesian-space centroidal dynamics to model the CoM states and system momenta...
• Learning-Based Robot Controlframework70%
  The paper compares its BSB-based approach against a CoP margin baseline, which is a common control method, and discusses limitations of existing approaches.
  For comparative evaluation against a baseline criterion, another lift-and-hold trajectory was generated with the BSB constraint replaced by a margined range for CoP...
• Robot Motion Planningsubfield60%
  The paper uses trajectory optimization for lifting tasks, which is a form of motion planning, though the focus is on stability constraints.
  implemented with BSBs as explicit threshold constraints in the whole-body trajectory optimization for stable object-lifting control
• Robust and Sliding-Mode Robot Controlframework60%
  The paper's stability analysis and control are situated within the broader context of robust control for legged robots, though it does not explicitly use robust control methods.
  The stabilizing capability of a biped system depends on the system’s state and its current/desired contact configurations as well as the system’s design and control parameters.
• Roboticssubfield50%
  The paper addresses humanoid robotics and loco-manipulation, which falls under the broader AI robotics umbrella, but the methods are primarily model-based control rather than AI/ML.
  The demand for humanoid loco-manipulation tasks with an object has recently increased...

Abstract

The demand for humanoid loco-manipulation tasks with an object has recently increased, and most existing control approaches for stability in such tasks rely on heuristics or machine-learning techniques. This study rigorously analyzes and exploits the dynamic effects of the object mass on balance stability. By formulating the object mass parameters in the whole-body dynamics with distributed contact wrenches and centers of pressure at the stance contacts, their nonlinear effects on the system momenta and constraints are quantified. The dynamic models and constraints are incorporated into the construction of the balanced state basin/boundary (BSB), a partition of the center-of-mass state space for a biped system to maintain balance in its desired contacts. The implications of the BSB for prediction and control are highlighted using a humanoid robot and an analytically tractable reduced-order mechanism. The BSBs under different conditions of base of support, actuation capacity, and pose provide systematic analyses of the effects of object mass on the balancing capability of a system. In particular, the trade-off relationships between momentum regulation and limiting factors in balancing are characterized, introducing two key quantities of the object: the critical mass, at which the system's balancing capability is maximum, and the transition mass, which activates different limiting factors. In addition, sufficient conditions for imposing balanced states on a trajectory are established and implemented with BSBs as explicit threshold constraints in the whole-body trajectory optimization for stable object-lifting control of the humanoid, demonstrating the lift-and-hold and lift-and-release tasks with distinct mass properties in simulations and experiments.

Paper Context