Force Balancing of Robotic Mechanisms Based on Adjustment of Kinematic Parameters

Force balancing is a very important issue in mechanism design and has only recently been introduced to the design of robotic mechanisms. In this paper, a force balancing method called adjusting kinematic parameters (AKP) for robotic mechanisms or real-time controllable (RTC) mechanisms is proposed, as opposed to force balancing methods, e.g., the counterweights (CW) method. Both the working principle of the AKP method and the design equation with which to construct a force balanced mechanism are described in detail. A particular implementation of the AKP method for the RTC mechanisms where two pivots on a link are adjustable is presented. A comparison of the two methods, namely the AKP method and the CW method, is made for two RTC mechanisms with different mass distribution. The joint forces and torques are calculated for the trajectory tracking of the RTC mechanisms. The result shows that the AKP method is consistently better than the CW method in terms of the reduction of the joint forces and the torques in the servomotors, and the smoothing of the fluctuation of the joint force.

[1]  D. A. Streit,et al.  ‘Perfect’ Spring Equilibrators for Rotatable Bodies , 1989 .

[2]  Puren Ouyang.  Force Balancing Design and Trajectory Tracking Control of Real-Time Controllable Mechanisms , 2002 .

[3]  Clément Gosselin,et al.  Static balancing of spatial parallel Platform mechanisms-revisited , 2000 .

[4]  I. S Kochev.  General method for full force balancing of spatial and planar linkages by internal mass redistribution , 1987 .

[5]  Sunil K. Agrawal,et al.  Design and fabrication of an active gravity balanced planar mechanism using auxiliary parallelograms , 2001 .

[6]  G. G. Lowen,et al.  Balancing of linkages—an update , 1983 .

[7]  P. R. Ouyang,et al.  A NOVEL FORCE BALANCING METHOD FOR REAL-TIME CONTROLLABLE MECHANISMS , 2002 .

[8]  Cemil Bagci.  Shaking force balancing of planar linkages with force transmission irregularities using balancing idler loops , 1979 .

[9]  Fang-Xiang Wu,et al.  Nonlinear PD control for trajectory tracking with consideration of the design for control methodology , 2002, Proceedings 2002 IEEE International Conference on Robotics and Automation (Cat. No.02CH37292).

[10]  Clément Gosselin.  Static Balancing of Spherical 3-DOF Parallel Mechanisms and Manipulators , 1999, Int. J. Robotics Res..

[11]  Kazuo Kobayashi.  Comparison Between Spring Balancer and Gravity Balancer in Inertia Force and Performance , 2001 .

[12]  Yueqing Yu.  Complete shaking force and shaking moment balancing of spatial irregular force transmission mechanisms using additional links , 1988 .

[13]  G. G. Lowen,et al.  A New Method for Com-pletely Force Balancing Simple Linkages , 1969 .