Youngsu Cho

Kinematic analysis of tendon driven robot mechanism for heavy weight handling

This paper addresses the kinematic analysis of tendon driven manipulator for handling heavy weight. Contrary to elementary N, N + 1 or 2N type tendon manipulators, this paper propose a specific N + 2 type robot manipulator for handling heavy weight. Necessary kinematics and statics issues are discussed. A more extended N + a type can be designed if more freedom for load distribution to tendons is sought. Numerical examples are given to confirm the validity of the analysis.

Synthesis of tendon driven mechanism by null basis selection

This paper propose a novel method for designing N + α open-ended serial tendon-driven mechanism (STDM). The design method starts from assigning a set of desired null space bases and from these the structure matrix is optimized so that the mechanisms actuation capability is maximized. An illustrative synthesis example is provided.

Simultaneous identification of kinematic screw and joint compliance of elastic robot manipulators using deflected circular trajectories

In this paper, a new kinematic parameter calibration method is proposed for robot manipulators having elastic joints. Kinematic screw and compliance parameters are identified through the proposed calibration procedure, so that an enhanced kinematic accuracy is achieved. Traditional circular point analysis is modified to cope with new product-of-exponential (POE) kinematic model that accounts for joint deflection. Simulation result is provided to validate the proposed kinematic calibration method.

A manipulator with counterbalancing mechanism for safety in human-robot collaboration

Demands for human-robot collaboration in production line has increased and the problem of safety in robot becomes more and more important. This paper presents a manipulator with counterbalancing mechanism to secure safety of a human worker in human-robot collaboration environment by reducing a needed power to drive a manipulator. A counterbalancing torque to cancel out a gravitational torque was generated by a restoring force of spring. Also a control algorithm to minimize the effect of spring on tracking performance was proposed. Experimental results were suggested to verify the performance of the proposed method.

Stiffness characteristics of new modular type antagonistic tendon-driven joint systems

This paper presents a new antagonistic tendon-driven joint (TDJ) which has an advantage of enhanced stiffness characteristics. Detailed mathematical analyses on the stiffness of typical TDJs are worked out to compare the stiffness among them. Prototypes of the proposed TDJ design are introduced in the form of packaged modular structure that merges two TDJs generating a combined roll-pitch motion or similar ones. Numerical examples are given to confirm the superior stiffness of the proposed TDJ design.