Robust Adaptive Control of Automatic Guidance of Farm Vehicles in the Presence of Sliding
Robust Adaptive Control of Automatic Guidance of Farm Vehicles in the Presence of Sliding
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DOI：
10.1109/robot.2005.1570587
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发表时间：
2005-04
期刊：
影响因子：
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通讯作者：
H. Fang;R. Lenain;B. Thuilot;P. Martinet
中科院分区：
文献类型：
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作者：
H. Fang;R. Lenain;B. Thuilot;P. Martinet
随着农业应用的需求，高精度自动农业正在迅速成为现实。农用车辆的自动导引控制一直是人们研究的重点，在车辆无滑动的假设下取得了令人满意的结果。但不幸的是，纯滚动约束并不总是得到满足，特别是在农业应用中，其中工作条件是粗糙的和不可预期的。在本文中，路径跟踪控制的自主农用车辆存在滑动的问题。为了考虑滑移效应，建立了一个面向车辆的运动学模型，其中滑移效应作为理想运动学模型的附加未知参数。基于反推方法，提出了一种逐步设计自适应控制器的方法，在该方法中，时不变的滑动效应通过参数自适应来学习和补偿。从理论上证明了在滑移条件下，农用车的侧向偏差可以稳定在零附近，定位误差收敛到原点附近的一个邻域内。为了使自适应控制器对包括外部噪声和未建模的时变滑动分量在内的干扰具有更强的鲁棒性，通过集成变结构控制器或投影映射来改进自适应控制器。仿真结果表明，所设计的鲁棒自适应控制器能有效抑制滑模效应，保证较高的路径跟踪精度。
High-precision autofarming is rapidly becoming a reality with the requirements of agricultural applications. Lots of research works have been focused on the automatic guidance control of farm vehicles, satisfactory results have been reported under the assumption that vehicles move without sliding. But unfortunately the pure rolling constraints are not always satisfied especially in agriculture applications where the working conditions are rough and not expectable. In this paper the problem of path following control of autonomous farm vehicles in presence of sliding is addressed. To take sliding effects into account, a vehicle-oriented kinematic model is constructed in which sliding effects are introduced as additive unknown parameters of the ideal kinematic model. Based on backstepping method a stepwise procedure is proposed to design an adaptive controller in which time-invariant sliding effects are learned and compensated by parameter adaptations. It is theoretically proven that for the farm vehicles subject to sliding, the lateral deviation can be stabilized near zero and the orientation errors converge into a neighborhood near the origin. To be more robust to disturbances including external noises and unmodeled time-varying sliding components, the adaptive controller is refined by integrating Variable Structure Controllers (VSC) or projection mappings. Simulation results show that the proposed robust adaptive controllers can reject sliding effects and guarantee high path-following accuracy.