1994 Volume 56 Issue 4 Pages 61-66
An active trailer wheel steering control system was developed and reported previously. It has been confirmed that application of the system improves tracking performance of both types of trailers, in-line type and offset type. However, it is practically difficult to have rotational sensor fitted to front axle of a tractor to measure the steering angle of the tractor wheels. Therefore, a method to estimate the steering angle of the tractor wheels was developed and reported in this paper. Firstly, estimation methods were compared and it is concluded that the best method is observer method, and estimation by reverse calculation has accurate enough for practical application. In reverse calculation, the steering angle is calculated from the angle and angular velocity between the tractor and the trailer. Therefore, an active control method which uses the steering angle of the tractor wheels estimated from the angle and angular velocity between tractor and the trailer was developed and applied to in-line type roll baler of real size. Step response, 90 degree turn, zigzag running and forage harvesting tests were carried out. The results of experiments show that the performance of the active control method using estimated angle is almost the same as that of the method using measured angle.
