Research On Frog-Inspired Biomimetic Jumping Robot Actuated By Pneumatic Muscles And Its Key Technologies

Jumping robots can be widely applied in archaeology, interstellar probe, antiterrorism and resource exploration. Compared to wheeled robots and walking robots, jumping robots go forward by jumping movement, and have the characteristic of fast moving and good climbing ability. However, contact between jumping robots and ground varies during jumping process, and there exists impact to ground, which makes the jumping process emerges continuous state and discrete state, showing high nonlinear characteristics. Besides, how to plan trajectories in task space and joint space properly considering specified task is also a key challenge. Traditional jumping robots adopt the method of’motor+ spring’to provide power for jumping movement. This method usually needs complex transmission mechanism, such as gears and ratchets, which leads to stuck fault. Considering the downside, this research adopts pneumatic artificial muscles as power device to design mechanism of jumping robot considering its characteristics of large output force and simple transmission device. However, considering the high nonlinearity and force-displacement hysteresis of pneumatic muscles, its mechanical model is also a key challenge. Considering its high nonlinear mechanical model and gas compressibility characteristic, how to realize accurate position control is also a challenging problem.On the basis of existed deep research of frog physiological structure and jumping characteristics completed by our research group, this paper takes pneumatic muscles as actuators to construct frog-inspired jumping robot, and study the problems of kinetics and dynamics characteristics, mechanical models of pneumatic muscles, trajectory planning under regular grid to realize specified jumping task, controlling method of pneumatic muscle actuated joint and motion controller of the robot.This paper firstly analyzes the frog physiological structure and jumping characteristics, builds up the equivalent six-bar-mechanism model of frog jumping movement, and performs the optimizing simulation of six-bar-mechanism model, which is used as a reference for mechanical design of robot; designs rear leg of the robot, and then designs the forelimb and body. According to the need of detecting the robot status, chooses sensors for the robot.Analyzes the unactuated characteristic of the jumping process of the robot, and divides the jumping process into different sub phases. Establishes unified kinematic model; analyzes the dynamic characteristics of jumping process, establishes continuous dynamic equation and discrete dynamic equation using Lagrangian equation, respectively, and analyzes dynamic switch condition among different sub phases. Mechanical properties of pneumatic muscles are the basis of robot design and control. Study the mechanical properties of pneumatic muscles. Model mechanical behaviors of pneumatic muscle from working mechanism point and experimental point, respectively. Taking Chou model as the base, mechanism model considers elasticity of rubber, elasticity of fiber mesh and internal friction; considering the need of actual controlling of pneumatic muscles, build phenomena model by empirical method. Considering the complex charging and discharging process inside pneumatic muscle, this paper establishes phenomena models for charging process and discharging process using experimental data.Considering the specified jumping distance and height under regular grid as the goal, this paper studies the trajectory planning problem. Performs the deep analysis of the problem of solving unactuated joint. Taking the minimization of the peak force to the robot by ground as the goal, optimize the trajectory in task space; on the basis of trajectory planning in the task space, and taking the minimization of consumed active torques as the goal, optimize the trajectories in joint space. Simulation is then performed.Build the controller of the robot and study the controlling strategy of pneumatic muscle actuated joint. Construct the 1-DOF set-up of pneumatic muscle actuated joint. Combining the established dynamic model of setup and phenomena model of pneumatic muscle, this paper performs the research of PID cascade position controlling method and RBF PID cascade position controlling method. On the basis of position controlling strategy of pneumatic muscle actuated joint, build the controller of the robot, and adopts RBFNN-PID cascade method to control each joint. Performs the matlab/adams combined simulation.Designs the controlling system of the robot and performs experiments of posture adjusting and jumping movement. Takes embedded micro-controller as the core, constructs the controlling system. Performs experimental study of posture adjusting and jumping capacity of the rear leg to prove the effectiveness of controlling strategy for pneumatic muscle actuated joint and the feasibility of taking pneumatic muscles to construct jumping mechanism. Performs experimental study of posture adjusting and jumping capacity of robot to prove the effectiveness of the motion controller of the robot, feasibility of trajectory planning and taking pneumatic muscles to construct the jumping robot.