Constant-Jacobian parallel mechanism comprising five-freedom-degree branches

Abstract

A constant-Jacobian parallel mechanism comprising five-freedom-degree branches comprises a fixed platform, a movable platform and three branches connected with the fixed platform and the movable platform. The first branch is five-freedom-degree branch PPRU structure and comprises a first movement pair, a second movement pair, a first rotating pair and a first universal hinge. The second branch is a five-freedom-degree branch PRPU structure and comprises a third movement pair, a second rotating pair, a fourth movement pair and a second universal hinge. The third branch is a five-freedom-degree branch CRU structure and comprises a first cylinder pair, a third rotation pair and a third universal hinge. The constant-Jacobian parallel mechanism comprising the five-freedom-degree branches can achieve spatial three-dimensional movement of the movable platform, when movement pairs of the first movement pair, the third movement pair and the first cylinder pair are used as driving input, the feature that the Jacobian matrix is constant is achieved, indexes, relevant to the Jacobian matrix, describing the movement performance and the force transmission performance of the mechanism also keep constant, the problems of control, path planning and the like of the parallel mechanism are solved, and much convenience is brought to analysis and design of the mechanism.

Description

technical field [0001] The invention belongs to the field of parallel robots, in particular to a parallel mechanism. Background technique [0002] Parallel mechanism has been widely used because of its advantages of high rigidity, strong bearing capacity, high precision, and non-overlapping errors. The typical six-DOF parallel mechanism Stewart platform and its deformation are widely used in various simulated motions, such as the motion simulation of aircraft, automobiles, ships, etc. With the expansion of the application field of parallel mechanisms, in many cases, all six degrees of freedom in space are not required to meet the requirements. Under this demand, parallel mechanisms with fewer degrees of freedom have attracted widespread attention from scholars at home and abroad, especially the three-degree-of-freedom movement. Parallel mechanism, among which the Delta mechanism is a three-degree-of-freedom mobile parallel mechanism that is very successful in industrial pro...

AI Technical Summary

Problems solved by technology

At present, most of the performance indicators of the mechanism are evaluated based on the Jacobian matrix. If the Jacobian matrix of the mechanism changes, the related performance indicators, such as motion and force transmission performance indicators, will also change accordingly. It has brought many difficulties to the design, which has brought inconvenience to the improvement of the control precision of the mechanism.

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