High speed path tracking application in harsh conditions: Predictive speed control to ensure the limit of the lateral deviation
2016
Braconnier, J.B. | Lenain, R. | Thuilot, B. | Rousseau, V.
One of the most important points on path tracking application, is the capability of the robot to track the desired path as accurately as possible. Results presented in the literature in on-road contexts are convincing, but cases of off-road mobile robots introduces other issues, like bad grip conditions or non flat ground. These issues can lead to a lack of accuracy of the tracking, even more when we consider high speed. The quality of the tracking depends on the modelling and the control laws used, but it depends also on the path to follow and on the soil conditions. If some small errors may be acceptable, it is sometimes mandatory to have a limited error, in particular when avoiding an obstacle, or when moving on a narrow pathway. The aim of the proposed algorithm in this paper, is to determinate the maximum reachable velocity of the robot during the tracking, to ensure lateral error will stay below a desired limit. In order to achieve this, a predictive approach, taking into account the evolution of dynamic model, control laws, and actuators properties, is proposed. It permits to predict the forthcoming tracking error, and consequently to estimate the maximum velocity that the robot can reach in accordance with the set maximum deviation allowed.
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