A Unified Whole-Body Control Method for 3D Target Visual Tracking with a Mobile Manipulator

Visual tracking with a mobile manipulator is required to continuously keep a moving target near the center of the camera’s field of view. Conventional methods generally employ either the mobile base or the manipulator alone for target tracking. However, base-only tracking provides limited task-space motion capability, whereas arm-only tracking is restricted by the finite workspace and joint limits of the manipulator. To address this problem, this paper proposes integrating base–camera alignment and gain-scheduling visual servoing controller into a unified whole-body control frame to generate coordinated motion of the mobile base and the robotic arm for visual tracking. The mobile base and six-joint manipulator are represented as an eight-degree of freedom kinematic system, and their velocities are determined simultaneously by a quadratic program incorporating joint and velocity constraints. Auxiliary objectives regulate arm manipulability, transient motion allocation, and base–camera alignment. The proposed method enables the robot to reactively track a moving target in a three-dimensional workspace while maintaining the desired target distance. Experiments on a mobile manipulator demonstrate coordinated base–arm motion for the tested target-tracking tasks. In an illustrative controller-level step response, gain scheduling reduces the settling time from 7.99 s to 2.39 s relative to the previous fixed-gain configuration.