含多级液压缸的大型液压举升系统时间最优轨迹规划

摘要

采用分段线性控制方法控制含多级液压缸的大型液压举升系统时,由于加速度不连续,易在举升过程中产生较大冲击.为消除举升过程中多级液压缸换级碰撞带来的液压冲击,提出了采用分级规划的策略.对每一级进行轨迹规划时,为保证举升过程的平稳性,采用B样条函数对举升负载的轨迹进行规划.在综合考虑工程实际中的液压系统压力、流量及负载横向过载约束的基础上,建立了举升系统的时间最优轨迹规划模型.针对解析法计算多级液压缸的最大速度和驱动力困难等问题,通过引入罚函数,提出一种改进的粒子群优化算法求解时间最优轨迹规划模型.含二级液压缸的某大型液压举升系统的仿真结果表明,提出的分级规划策略和时间最优轨迹规划方法是有效的.%Acceleration discontinuity, caused by piecewise linear control method, which is adopted in the large hydraulic driven lift system with multistage hydraulic cylinder, results in big impact in erect process unavoidably. Stage planning strategy was proposed to avoid hydraulic impact caused by stage change of multistage hydraulic cylinder. In order to make every stage movement stable, B-spline function was adopted to plan trajectory of driven lift system. Based on the actuating constrains, such as hydraulic pressure and flux, tangential overload of the load in the engineering, the optimal time trajectory planning model was constructed. To solve the problem of calculating maximum velocity and maximum driving force of the multistage hydraulic cylinder, an improved particle swarm optimization (PSO) algorithm was proposed to solve the optimal time trajectory planning model by introducing penalty function. The simulation results of the lift system with two-stage hydraulic cylinder show that the stage planning strategy and optimal time trajectory planning method are feasible.