Modeling And Tracking For Mechanical System With Friction And Backlash

Friction and Backlash widely exist in mechanical systems. Friction exists the surface ofrelative motion which is a complex dynamic behavior. The behavior will cause the hysteresiseffect in a low-velocity regime. Because the drive unit often does not contact load directlyinstead of gears or screws in mechanical system, it appears backlash. In many mechanicalsystems, the effect of friction and backlash overlaps and concurrences. In high precisioncontrol systems， a controller designed to compensate only the friction may perform poorly inthe presence of backlash, and vice versa. However, in the current study of high precisionmechanical motion control system, there are few literature involves the control problemsconsidering both friction and backlash.In this paper, we study the modeling and tracking control for the mechanical system withfriction and backlash. This dissertation focuses on the following work:Firstly, by reading related literature both at home and abroad, combined with the relatedtheory research status at home and abroad, modeling and compensation control are analyzedfor the hard nonlinearity friction and backlash respectively. The research purpose ofmechanical system with friction and backlash is presented.Secondly, the actual mechanical system with friction and backlash is modeled. Weconsider the SRV02-ET mechanical rotary motion experiment platform as the research object.The compensation and tracking control methods involved both the nonlinearity friction andbacklash are discussed.Thirdly, a robust adaptive control algorithm is developed for a class of nonlinear systemswith unknown backlash-like hysteresis. The projection algorithm is used for parametersestimation. The adaptive law is designed. The convergence property of the system is provedby selecting the appropriate Lyapunov function. The simulation results verify the feasibility ofthe method.Fourthly, for the mechanical system with friction and backlash, the sliding frictionrelated with speed is adopted in the friction part. A continuous dead zone backlash model isadopted in the backlash part. Combining with the nonlinear observer, an adaptive controller isdesigned. The routh stability theory is used to prove that the system can asymptotically converge to a steady state. The simulation and experimental results verify that the system hasgood tracking performance.Fifthly, based on LuGre friction model and continuous dead zone backlash model,combined with backstepping adaptive algorithm, a robust adaptive controller is designed tocompensate the friction and backlash. The double observer is adopted to estimate the internalfriction variable is. The designed adaptive law is used to estimate the system parameters. Theboundedness and convergence of the closed-loop system are guaranteed from a Lyapunovstability analysis. The effectiveness of the proposed control scheme is verified throughsimulation results.Finally, we summarized the control methods for the mechanical system with friction andbacklash, and analyzed the advantages and disadvantages of various control strategies. On thebasis of the article, the corresponding solution is put forward to solve these problems...