Simultaneously achieving low trajectory errors and compliant control\emph{without} explicit models of the task was effectively addressed withCompliant Movement Primitives (CMP). For a single-robot task, this means thatit is accurately following its trajectory, but also exhibits compliant behaviorin case of perturbations. In this paper we extend this kind of behavior withoutexplicit models to bimanual tasks. In the presence of an external perturbationon any of the robots, they will both move in synchrony in order to maintaintheir relative posture, and thus not exert force on the object they arecarrying. Thus, they will act compliantly in their absolute task, but remainstiff in their relative task. To achieve compliant absolute behavior and stiffrelative behavior, we combine joint-space CMPs with the well known symmetriccontrol approach. To reduce the necessary feedback reaction of symmetriccontrol, we further augment it with copying of a virtual force vector at theend-effector, calculated through the measured external joint torques.Real-world results on two Kuka LWR-4 robots in a bimanual setting confirm theapplicability of the approach.
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