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Abstract
In this paper, an improved time-optimal control algorithm is formulated to guarantee the tracked vehicle moves along the desired path. For tracked vehicles, the track is driven by the sprocket. During tracking, the velocity cannot change abruptly, or it will cause extra slippage of the track and mechanical damage of the whole system. Considering the dynamic constraints of the track, a cubic spline cure, which could meet the dynamic limits, is chosen as the tracking trajectory. Also the kinematic and positional error model of tracked vehicles is established. The control algorithm is implemented in MATLAB, and after a series of simulation, co-efficiency the curve is determined to better the validity and accuracy of the control system. Through comparison with PID control strategy in previous work, the superiority of this algorithm is confirmed.
Keywords: Tmcked vehicle, Path tracking, Algorithm
1. Introduction
Tracked vehicles are broadly used in the area of unpredictable and terrain condition. For deep sea mining, tracked vehicles are superior to many other kinds of vehicles, for they have larger contact area of tracks and can provide better traction. During working, the deep sea tracked vehicle goes on the extremely cohesive soil, and because of the slippage from the track, for the track vehicle, it is difficult to move long the desired path. To avoid this phenomenon, path tracking control is of most significance.
As for the path tracking, a great number of studies have been carried out since Kanayama's pioneering work [1], In liis work, the kinematic model of mobile robots was established, and the proposed tracking method can be used for later studies. Since then, various different path planning methods have been addressed. The methods used can be sorted into two types, the first is Lyapunov function[2]-[4], and the second is backstepping method[5]-[6], Also, many researchers paid much attention to the curvature continuity of the tracking path, and a lot of tracking curves are formulated such as clothoid pair curve [1], quadratic curve [7], polynomial curve [8], hyperbolic curve [3], and etc. At the same time, other scholars focused on the time-optimal trajectory planning. Yet, these studies concentrate on the mobile robots and the methods are too complicated.
For tracked vehicles, the key problem is the slippage of the track....