Oftadeh Reza, Ghabcheloo Reza, Mattila Jouni
Department of Computer Science and Engineering, Texas A&M University, College Station, TX 77840, USA.
Department of Automation Technology and Mechanical Engineering, Tampere University, 33720 Tampere, Finland.
Sensors (Basel). 2021 Nov 17;21(22):7642. doi: 10.3390/s21227642.
This paper presents a nonlinear, universal, path-following controller for Wheeled Mobile Robots (WMRs). This approach, unlike previous algorithms, solves the path-following problem for all common categories of holonomic and nonholonomic WMRs, such as omnidirectional, unicycle, car-like, and all steerable wheels. This generality is the consequence of a two-stage solution that tackles separately the platform path-following and wheels' kinematic constraints. In the first stage, for a mobile platform divested of the wheels' constraints, we develop a general paradigm of a path-following controller that plans asymptotic paths from the WMR to the desired path and, accordingly, we derive a realization of the presented paradigm. The second stage accounts for the kinematic constraints imposed by the wheels. In this stage, we demonstrate that the designed controller simplifies the otherwise impenetrable wheels' kinematic and nonholonomic constraints into explicit proportional functions between the velocity of the platform and that of the wheels. This result enables us to derive a closed-form trajectory generation scheme for the asymptotic path that constantly keeps the wheels' steering and driving velocities within their corresponding, pre-specified bounds. Extensive experimental results on several types of WMRs, along with simulation results for the other types, are provided to demonstrate the performance and the efficacy of the method.
本文提出了一种用于轮式移动机器人（WMR）的非线性通用路径跟踪控制器。与先前的算法不同，这种方法解决了所有常见类型的完整和非完整WMR的路径跟踪问题，例如全方位、单轮、类似汽车以及所有可转向轮的机器人。这种通用性是两阶段解决方案的结果，该方案分别处理平台路径跟踪和车轮运动学约束。在第一阶段，对于去除了车轮约束的移动平台，我们开发了一种路径跟踪控制器的通用范式，该范式规划从WMR到期望路径的渐近路径，并据此推导出所提出范式的一种实现。第二阶段考虑车轮施加的运动学约束。在这个阶段，我们证明所设计的控制器将原本难以处理的车轮运动学和非完整约束简化为平台速度和车轮速度之间的显式比例函数。这一结果使我们能够为渐近路径推导一种封闭形式的轨迹生成方案，该方案能持续将车轮的转向和驱动速度保持在其相应的预先指定范围内。提供了在几种类型的WMR上的大量实验结果，以及其他类型的仿真结果，以证明该方法的性能和有效性。
