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除草机器人自适应快速积分终端滑模跟踪控制技术

Adaptive Fast Integrating Terminal Sliding Mode Tracking Control Technique for Weeding Robot

  • 摘要: 智能除草机器人在草坪作业时,易受到外界扰动以及系统不确定性的影响,从而导致轨迹跟踪收敛时间长以及跟踪效果差等问题。因此,设计一种面向轨迹跟踪的自适应快速积分终端滑模控制算法。首先,考虑驱动轮动力学特性以及未建模误差、外界干扰、动静摩擦等不确定性因素,建立除草机器人的动力学模型。然后基于所建立的动力学模型,设计自适应快速积分终端滑模控制器。所提出的控制器结合了快速终端滑模、积分滑模和自适应估计技术的优点,能够实现期望的跟踪性能并抑制控制信号抖动。同时,在不需要明确系统不确定性和外界干扰上界的情况下,可以通过所设计自适应估计项进行实时补偿,提高系统的鲁棒性。最后,通过仿真和试验验证了该方法的有效性。试验结果表明,所设计的控制器能够使跟踪误差在有限时间内快速收敛,并且横向误差绝对值不超过0.097 9 m,纵向误差绝对值不超过0.102 6 m,航向角误差绝对值不超过0.057 8 rad,保证除草机器人准确跟踪作业路径,同时具有较强的鲁棒性。

     

    Abstract: When the intelligent weeding robot was working in the lawn, it was easy to be affected by external disturbance and system uncertainty, which led to long tracking convergence time and poor tracking effect. Therefore, an adaptive fast integrating terminal sliding mode control algorithm for trajectory tracking was designed. Firstly, the dynamics model of the weeding robot was established by considering the dynamic characteristics of the driving wheel and uncertainties such as unmodeled errors, external interference and dynamic and static friction. Then based on the established dynamic model, an adaptive fast integrating terminal sliding mode controller was designed. The proposed controller combined the advantages of fast terminal sliding mode, integral sliding mode and adaptive estimation technology to achieve the desired tracking performance and suppress control signal jitter. At the same time, without specifying the upper bound of the system uncertainty and external interference, the designed adaptive estimation can be used for real-time compensation to improve the robustness of the system. Finally, the effectiveness of the proposed method was verified by simulation and experiment. The experimental results showed that the designed controller can make the tracking error converge quickly in a limited time, and the absolute value of the lateral error was no more than 0.097 9 m, the absolute value of the longitudinal error was no more than 0.102 6 m, and the absolute value of the heading angle error was no more than 0.057 8 rad, which can ensure the robot to track the working path accurately and have strong robustness.

     

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