基于MPC−FAPID的复杂工业场景轮式巡检机器人轨迹跟踪控制

Trajectory tracking control of wheeled inspection robots in complex industrial scenarios based on MPC-FAPID

  • 摘要: 目前针对巡检机器人轨迹跟踪控制的研究主要存在以下问题:① 在应对非对称负载扰动时,双电动机同步控制精度不足。② 单一控制结构难以兼顾预测优化与动态抗扰能力。③ 在复杂多变路况(道路坡度、路面状态发生较大变化等)下,控制算法的自适应性与鲁棒性仍有待提升。针对上述问题,提出了一种基于模型预测控制(MPC)与模糊自适应PID(FAPID)算法(即MPC−FAPID)的分层双闭环轨迹跟踪控制方法。基于四轮差速巡检机器人运动学模型,在控制量及控制增量中加入相应的约束,完成了基于MPC的轨迹跟踪控制器设计。针对四轮差速巡检机器人轮速易受干扰导致控制不协调的问题,通过引入FAPID算法,减少四轮差速巡检机器人运动过程中的电动机转速误差,仿真结果表明:FAPID算法能有效降低同步偏差,其精度及鲁棒性均优于PID控制与鲸鱼PID控制算法。针对单层控制结构难以兼顾预测能力和抗干扰性的问题,设计了基于MPC−FAPID的分层双闭环控制器:主环MPC实现轨迹跟踪误差补偿和多约束处理,从环FAPID抑制负载扰动影响。仿真结果表明:在直行上缓坡仿真工况下,MPC−FAPID的调整时间为0.87 s,相比MPC−PID,MPC−鲸鱼PID,能更迅速地调整机器人位姿靠近原始轨迹;在连续转弯仿真工况下,相较于MPC−PID与MPC−鲸鱼PID,MPC−FAPID能更好地捕捉原始轨迹的变化趋势,横向、纵向与航向角的最大误差分别为−0.051 m,0.000 47 m,0.0408 rad。实机试验结果表明:相比MPC−PID,MPC−FAPID在多目标点轨迹跟踪实机试验中横向最大误差降低了88.24%,纵向最大误差降低了87.76%。

     

    Abstract: Existing research on trajectory tracking control of inspection robots mainly suffers from the following problems: ① insufficient synchronization control accuracy of dual motors under asymmetric load disturbances. ② difficulty of a single control structure in balancing predictive optimization and dynamic disturbance rejection. ③ poor adaptability and robustness of control algorithms under complex and variable road conditions (e.g., varying slopes and surface states). To address these problems, a hierarchical double-closed-loop trajectory tracking control method based on Model Predictive Control (MPC) and Fuzzy Adaptive PID (FAPID) algorithms, namely MPC-FAPID, was proposed. Based on the kinematic model of a four-wheeled differential inspection robot, corresponding constraints were imposed on the control variables and control increments, and an MPC-based trajectory tracking controller was designed. To solve the problem of uncoordinated control caused by wheel speed disturbances in four-wheeled differential robots, the FAPID algorithm was introduced to reduce motor speed errors. The simulation results showed that the FAPID algorithm effectively reduced synchronization error, and its accuracy and robustness were superior to those of PID control and whale-optimized PID control. To overcome the limitation that a single-layer control structure could not balance predictive capability and anti-disturbance performance, a hierarchical double-closed-loop controller based on MPC-FAPID was designed: the outer loop MPC compensated for trajectory tracking errors and handled multiple constraints, while the inner loop FAPID suppressed load disturbance effects. Simulation results indicated that under straight-line motion on a gentle slope, the MPC-FAPID achieved an adjustment time of 0.87 s, which enabled faster convergence of robot pose to the reference trajectory compared with MPC-PID and MPC-whale-optimized PID. Under continuous turning conditions, compared with MPC-PID and MPC-whale-optimized PID, the MPC-FAPID better captured the variations in the reference trajectory, with maximum lateral, longitudinal, and heading angle errors of −0.051 m, 0.000 47 m, and 0.040 8 rad, respectively. Experimental results showed that, compared with MPC-PID, MPC-FAPID reduced the maximum lateral error by 88.24% and the maximum longitudinal error by 87.76% in the multi-target point trajectory tracking test.

     

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