#x2014;This paper proposes a control algorithm for the scrollic (synchronously closing with rolling constraints) gripper in order to control the trajectory of an object grasped outside the workspace toward the center of the gripper. The gripper has fingers composed of two cylinders in parallel, the translation and rotation of which are independently driven by direct-drive motors. The algorithm is based on sensory information about angular displacements of the cylindrical fingers, i.e. rollers. In fact, the object has direct affects on the rollers and the displacements are actively collected by rotary encoders. That is, contact sense not by tactile sensors but by intrinsic angular sensors is utilized. The algorithm yields the gripper to reduce a dynamic decoupled behavior and makes it compliant not only to close but also to open during a close motion. The algorithm presents a high level of tolerance concerning uncertainties about the object's position, orientation, size, shape and weight. The kinematics, the design concept and the control algorithm of the gripper are shown. Also, these are verified by grasp demonstrations.
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