No abstract

In this paper, a design and optimization approach for a 2-dof manipulator based on parallelogram mechanism for high dynamic application is proposed. After the kinematic and dynamic analysis, several advantages of the mechanism are illustrated which make it possible to reach good dynamic performance through mechanism optimization. Based on the idea of design for control (DFC), a novel kind of multi-objective optimization method is presented. Several index considering both kinematic and dynamic performances are chosen as objective functions and design constraints. The cross-section area and length of the linkages are chosen as the design variables. NSGA-II algorithm is introduced to solve this complex multi-objective optimization problem. And a new expression for the measuring of dynamic coupling degree with clear physical meaning is proposed, it shows that the optimized mechanism has an approximate decoupled dynamics structure, and each active joint could be regarded as a linear SISO system. The final optimized mechanism could be used in high speed pick-plate applications only using simple linear controller.

No abstract

A gravity compensation algorithm for master manipulator used in minimally invasive robot surgery is proposed in this paper. The Lagrange dynamic equation is used to solve the motor output torque for balancing the master gravity. To avoid time delay in signal processing, multi-thread and multi-event technology are used in software control system. With the algorithm, the force by hand is very small under the condition of exist gravity compensation, less output more than 90% of the external force compared with the lack of gravity compensation.

To grind sculptured surface by swing motion, it’s needed to interpolate the discrete data nodes on the arc-driving surface. To ensure that all the sample points locate on the arc surface, a novel unfolding parameter curve is proposed. Firstly, all the discrete data are stretched onto a plane, inside which the cubic B-spline curves are interpolated. After that, some points are sampled from the spline curves and bended to the arc-driving surface according to the swing radius. To eliminate cutting vibration and chord error exceeds limitation; radial speed is tuned by controlling the chord error. The simulation results are given to prove the proposed algorithm.