Statical balancing of a robot mechanism with the aid of a genetic algorithm

Abstract

ln designing robots statical balancing is of great importance. It enables essential reduction of the required motor power. Elimination of significant reduction of the gravity load at a powered joint can also lead to a simpler and more effective control system. It is shown that this problem can be formulated as an optimization problem. As objective function the average force on the gripper in the working area is used. It is shown that those forces can easily be derived with the aid of a Computer Algebra System. The lengths of the links and angles between them as well as the stiffness of springs can be considered as design variables. It is shown that a general design program based on Monte Carlo methods and genetic algorithms, that has a graphical interface that allows the user to modify search intervals, is very appropriate to these kinds of problems. As an example an industrial robot with 6-DOF is treated. The robot has a spring balancing system that has to be optimized. The robot with the parameters of its balancing system found this way is evaluated with an existing multibody dynamics program SPACAR that simulates the movements of the robot and calculates the forces at its powered joints. With the aid of MATLAB the forces in the working area are plotted in a 3D figure. The method described in this article is general and very appropriate to solve problems in practice without simplifications.

Intrinsically Safe Robot Arm: Adjustable Static Balancing and Low Power Actuation

“…In a well designed spring-balanced system the total potential energy in mass and spring remains constant, independent of the configuration of the manipulator. This concept was generalized for one degree-of-freedom by Streit and Gilmore [29] and later extended to more dimensions for various robots [1,9,11,26,27,31,35,36]. To allow the manipulator to handle a range of payloads, the balancing system will have to be adjustable.…”

Design and Prototyping of a New Balancing Mechanism for Spatial Parallel Manipulators

“…Balancing by using an auxiliary mechanism can be presented in the following manner: B3.1. Balancing by using an auxiliary linkage [19][20][21][22][23][24][25][26][27][28][29].…”

Torque minimisation of the 2-DOF serial manipulators based on minimum energy consideration and optimum mass redistribution

“…Such an approach allows zero free length springs to be used, which is more favourable for realisation of complete balancing. (e) Spring balancing by using an auxiliary linkage [21][22][23][24][25][26][27][28][29][30][31]. In these studies the articulated dyads, pantograph mechanism and parallelogram structure are used as the added systems for optimal displacements of the springs.…”