Model-free self-adaptive nonsingular terminal sliding mode control method for sand blasting derusting parallel robot

Abstract

The invention discloses a model-free self-adaptive nonsingular terminal sliding mode control method for a sand blasting derusting parallel robot. In order to obtain a dynamic model which can comprehensively reflect dynamic characteristics and can realize real-time control, a time delay estimation method of a Stewart parallel mechanism dynamic model is provided to online obtain a system model; in order to solve the problem of joint friction force existing in the sand blasting derusting parallel robot system, the model-free self-adaptive nonsingular terminal sliding mode control method is provided; furthermore, an adaptive rule capable of rapidly adjusting switching gain is defined, so that the adaptability of the system to the coulomb friction force direction and amplitude sudden change is improved. According to the model-free self-adaptive nonsingular terminal sliding mode control method for the sand blasting derusting parallel robot based on the Stewart parallel mechanism, the problem of joint friction force existing in the sand blasting derusting parallel robot system is effectively solved, meanwhile, sliding mode control buffeting is weakened, and high-precision trajectory tracking control of the sand blasting derusting parallel robot system is achieved.

Description

technical field [0001] The invention relates to the field of sandblasting and rust removal of steel box girders, in particular to a control method for a sandblasting and rust removal parallel robot based on a Stewart parallel mechanism. Background technique [0002] For the sand blasting and rust removal of steel box girders, the traditional manual operation is inefficient and has a lot of safety hazards, and the quality of sand blasting and rust removal depends on the experience of workers. For this reason, a parallel sand blasting and rust removal based on Stewart parallel mechanism has been developed. robot. The parallel robot for sandblasting and derusting is based on the motion of the Stewart platform. The Stewart parallel mechanism has a typical space closed-chain structure, and there are a lot of kinematic constraints. Traditional dynamic modeling methods such as Lagrange method and Newton-Euler method are difficult to establish a dynamic model of the Stewart platfor...

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Problems solved by technology

However, when the direction of Coulomb friction changes suddenly at certain moments, the pulse-shaped delay error only occurs at certain moments, the existing non-singular terminal sliding mode control method conservatively selects a fixed switching gain, in order to effectively solve the pulse-shaped For the problem of delay error, it is necessary to always use a switching gain greater than the upper bound of the pulse-type delay error, which is likely to cause serious chattering of sliding mode control and reduce tracking accuracy

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