An impedance-based control architecture for multi-robot cooperative dual-arm mobile manipulation

Abstract

Abstract-Cooperative manipulation in robotic teams likely results in an increased manipulation performance due to complementary sensing and actuation capabilities or increased redundancy. However, a precise coordination of the involved manipulators is required in order to avoid undesired stress on the manipulated object. Extending the workspace of the robots by means of mobile platforms greatly enlarges the potential task spectrum but simultaneously poses new challenges for example in terms of increased kinematic errors. In this paper we show how kinematic errors in the closed kinematic chain originating from uncertainties in the geometry of object and manipulators limit the cooperative task performance. We extend an impedance-based coordination control scheme towards mobile multi-robot manipulation to limit undesired internal forces in the presence of kinematic uncertainties. Furthermore, we employ a task-space decoupling approach to reduce the impact of disturbances at the mobile platforms on the end effectors. The presented control scheme for cooperative, mobile dualarm manipulation is applicable in real-time and suitable for a team of heterogeneous manipulators. We evaluate the presented architecture by means of a large-scale experiment with four 7DoF manipulators on two mobile platforms.

Multi-robot manipulation controlled by a human with haptic feedback

“…Hence, in the transient phase the desired positions are not geometrically consistent with the object geometry any more. Desired trajectories which are not geometrically consistent with the object geometry result in an undesired internal force acting on the object [2]. This must be strictly avoided in a cooperative manipulation task.…”

“…Due to (14) the operator induces a breakup of the formation in the transient phase of the desired trajectoriesx c (t) by his movement x h,k . The divergence of the desired trajectories results in an internal force acting on the object [2]. To avoid this breakup (14) in the transient phase, only a single controllable state is required.…”

“…Since we only consider translational movements for the manipulators, the rotational impedance parameters are in gravity compensation. A workspace extension for all robotic manipulators by a mobile platform can be accomplished according to a potential function approach presented in [2]. In our experiments the object is an exercise ball with a diameter of 0.65 m and a weight of 1.159 kg.…”

Grasp pose estimation in human-robot manipulation tasks using wearable motion sensors

“…Thus, a biased estimate of the grasp pose, i.e. the relative kinematics between the human hand and the robotic end-effector, causes undesired interaction wrenches between partners [4] and results in non-matching robot and human trajectories. The undesired interaction wrenches bias human intention recognition schemes based on interaction wrenches [3].…”

Iterative optimal feedback control design under relaxed rigidity constraints for multi-robot cooperative manipulation

“…Many recent research activities on multi-robot problems focus on distributing motion commands of interconnected robots based on the desired movement of a rigid body using advanced robot dynamics [1]- [3]. Since contact forces are always present in the cooperation of robots, their inclusion into the control scheme facilitates a desired compliant interaction, called impedance control.…”