基于力反馈的拖拉机驾驶机器人换挡机械手模糊PID自适应控制方法研究

[目的]针对目前四轮农用拖拉机换挡器的特殊结构,设计了新颖的拖拉机驾驶机器人换挡机械手,将拖拉机换挡操纵杆的三维球面运动转化为直角坐标中的二维直线运动,机械手可以沿X、Y 2个方向的运动来实现选、换挡。[方法]拖拉机换挡操纵杆在X方向的换挡阻力很小,且选挡位置固定,因此在X方向采用传统的位置控制;由于拖拉机换挡操纵杆在Y方向换挡时,位置重复性差,换挡过程中的力存在时变、非线性等特征,难以通过位置控制进行纵向换挡,因此,构建基于力反馈的拖拉机驾驶机器人换挡机械手模糊PID自适应控制系统,并通过力信号的小波入位检测判断换挡手柄是否成功入位。[结果]仿真结果及在国产JINMA(金马)300E型拖拉机的换挡试验均表明:模糊PID自适应控制方法具有良好的力跟踪特性,与传统PID控制方法相比,该控制方法可实现换挡过程中PID参数的在线自整定,换挡力跟踪误差低于6%,超调量小于10%,上升时间缩短46%。[结论]基于力反馈的模糊PID自适应控制能够实现拖拉机驾驶机器人的平顺换挡,具有较强的鲁棒性和自适应能力。
[Objectives]Respect to the special structure of the gear shift device of the four-wheel agricultural tractor,this paper designed a novel gear shift mechanical arm of tractor robot driver,which can transform the three-dimensional spherical motion of tractor shift lever into two-dimensional linear motion in rectangular coordinates. The mechanical arm can shift in both X and Y directions to achieve selecting and changing gears. [Methods]This paper used the conventional position control algorithm to achieve shift in X direction because the shift resistance of the gear shift device is small in X direction and the shift position is fixed. And this paper constructed fuzzy-adaptive PID control system of shift manipulator of tractor robot driver in Y direction respect to the time-variable and nonlinear characteristic of the force during the process of movement of the gear shift device,and put forward a way of identifying the gears’ successful shift by force based on wavelet to judge whether the gears’ shift was in the successful shift position or not. [Results]The simulation results and gear experiments of the JINMA tractor of 300E type made in China show the fuzzy-adaptive PID control algorithm has good tracking characteristic of the shift force,and this algorithm can realize the PID parameters online self-tuning compared to the traditional PID control algorithm,for example the tracking error of the shift force was less than 6%,the overshoot was less than 10% and the rise time was reduced by 46%. [Conclusions]The fuzzy-adaptive PID control algorithm based on the force feedback can realize the gear shift smoothly by the tractor robot driver,which has strong robustness and self-adaptive ability