Research On Adaptive Backstepping Sliding Mode Control And Vibration Suppression For A Rigid-Flexible Manipulator

The development of new technology promotes evolution of manipulator, rigid-flexible manipulator has the advantages of both rigid manipulator which is not like tobring elastic deformation, but also has light weight for flexible manipulator, which savingenergy consumption due to movement of manipulator. For that reason, the rigid-flexiblemanipulator has been widely used in many fields. For instance, in space exploration, inorder to reduce power consumption during space exploration mission, many space rigid-flexible manipulators are applied. Also, in the military field, rigid-flexible manipulatorsare used to complete tasks in harsh environment. Rigid-flexible manipulators are used tofinish high-precision machining operation task.The rigid-flexible manipulator is a complex system made up of rigid manipulator andflexible manipulator, the flexible beam will generates elastic deformation caused byweight of payload on its end and the elastic deformation will influence accuracy oftrajectory tracking. There are vibration on the end of the flexible beam caused byinertance during the movement of manipulator. Uncertainty and disturbance willdeteriorate the control performance. In order to complete accurate trajectory tracking andsuppress vibration of the manipulator, it’s a need to establish a complete dynamic modelof the system and design a good controller.This paper researches a three-link hydraulic drive vehicle flexible manipulator with aload on its end, referencing the system dynamics equations established accordingLagrange Principle and the assumed mode method, the paper studies the trajectorytracking control and vibration suppression of the manipulator. The main contents andwork are shown as follows:First, the paper divides the rigid-flexible manipulator into two parts, the manipulatorsubsystem and the hydraulic subsystem. Referring to the Lagrange principle and theassumed mode method, this paper establishes the dynamic model of the manipulatorsubsystem; referring the fundamental principle of hydraulic system, the paper gets therelationships between control current、torque and rotary angle. The paper obtains thewhole dynamic model of the rigid-flexible manipulator referring a Jacobian matrixbetween the manipulator subsystem and the hydraulic subsystem. Considering there areuncertainties of the actual system and external disturbance, the paper obtains the completedynamic model of the system.Secondary, assuming that the external interference and uncertainties are bounded andthe upper boundaries are known，this paper designs a sliding mode controller based onswitching gain. The switching gain eliminates bad influence brought by uncertainties, theglobal sliding surface guarantees stronger robustness during the sliding mode andapproaching mode of the system, which overcoming the shortcoming of weaker robustness for traditional sliding mode control during the approaching mode. A saturationfunction is used to replace the sign function in the control current reducing chattering ofthe control current caused by sliding mode control. Simulation results verify validity ofthe controllerThirdly, considering that the uncertainties and external disturbances are usuallycomplex and their upper bounds are unknown, this paper designs an adaptivebackstepping sliding mode controller. The adaptive method is used to estimate the upperof uncertainty and extern disturbance, the adaptive backstepping sliding mode controlrealizes trajectory tracking and vibration suppression. Simulation results manifest validityof the controller.Finally, the paper gives a conclusion of the full paper, makes a expectation forfuture’s work.