Cooperative mobile manipulator with dual compliance controllers based on estimated torque and visual force

This paper proposes dual compliance controllers based on estimated torque and visual force on mobile manipulator to provide cooperativeness. A compliance control provides robot with affinity and adaptability to work in open environment. Generally, compliance control is a control system with trajectory compensation so that an external force may be followed. However, this paper compensates not only external force of physical sensation, but also virtual force of non-physical sensation based on visual information. Here, the robot will be compliance with wider sensation. The visual information is provided by high-speed vision sensor. The target object is attached with hexagon pattern of artificial markers to reduce the required image processing time. The distance approximation between the object and the camera is used as visual force not as position or speed reference that commonly used in visual servoing. Later, the visual force adjusts the mobile manipulator command reference. Finally, the experimental result shows the validity of the proposed method.