Design And Experimental Study Of Underactuated Gymnastics Robot

With the improvement of the intelligent level of the robot,higher requirements are placed on the motion control of the robot.The underactuated system refers to a typical nonlinear system in which the number of independent control variables of the robot system is less than the number of degrees of freedom.The system has the advantages of light weight,low energy consumption and high flexibility,and is widely used in space robots and underwater robots..Gymnastics robot is a typical application environment of underactuated system.The in-depth study based on gymnastics robot is of great significance to the development of other complex underactuated systems.Based on the Acrobot theory model,this paper studies the underactuated gymnastics robot and nonlinear system,aiming to design an underactuated robot that can achieve specific gymnastics movements.The main research contents of this paper are as follows:Firstly,the dynamic model of the two-link underactuated gymnastics robot is analyzed.According to the constraints of the gymnastic robot on the horizontal bar,the dynamic model of the bar is established by using the Lagrangian equation.Based on the dynamic model of the bar,a simplified dynamic model of the inverted balance position is established for the state characteristics of the gymnastic robot near the inverted equilibrium position.The dynamic model was built in Simulink and the correctness of the model was verified.Secondly,the underactuated gymnastics robot system is designed,including the mechanical system design and hardware circuit design of the gymnastics robot.The mechanical system design is based on the characteristics of gymnastics robot movement.Firstly,the overall scheme design is carried out.Then the design index is proposed,considering the energy accumulation,motion interference,routing layout,fault tolerance,etc.during the motion,according to the passive joint and the first link.The mechanical joint system of the gymnastics robot was designed in sequence,and the mechanical system of the gymnastics robot was designed.Finally,the designed mechanical system was in compliance with the expected indicators,and the strength and stiffness of the key components were checked.The hardware circuit takes STM32 as the control core.According to the sequence of current flowing into the control chip and control chip output command,the schematic diagrams of power supply circuit,undervoltage alarm circuit,hand motor drive circuit and sensing circuit are designed.Then the components are arranged reasonably.Designed a PCB board with processing conditions to establish a fully functional electrical system.Finally,the motion control method of gymnastics robot is studied,and the experimental platform of gymnastics robot is built.The design experiment verifies the effectiveness of the control strategy.Comparing the characteristics of energy increment method and energy convergence method,combined with the demand of inverted balance stage,the energy convergence method is used to control the robot swing;a linear quadratic regulator is designed for the control of the robot inverted balance phase.Based on the system dynamics equation and control method,the simulation model is established.According to the characteristics of the control method,reasonable energy switching conditions are set to enable the robot to achieve specific gymnastics movements.The control method is transplanted to the gymnastics robot system,the robot motion is controlled,and the experimental data drawing curve is collected.The control method is explained in the robot control from the experimental phenomena and the state quantity curve,and the gymnastic robot grabs the bar,swings,and stands up.Balance control verifies the effectiveness and robustness of the control method.