Kinematic Analysis of Multi-Axle Steering System for Articulated Vehicle

Steering of non-driven axles of semi-trailer results in improvement of maneuverability during negotiating sharp turn and reduces tyre drag and wear by relieving locked-in forces in comparison to non-steered axles. Among few, command steering mechanism is reported to be most efficient method of steering of articulated vehicles. In this type, the axles of semi-trailer are steered in relation with the articulation of tractor. The articulation angle of tractor is sensed by an actuation mechanism integrated on trailer at fifth wheel location and transferred hydraulically to the steering linkages. Mathematical equations have been developed based on Ackerman's Principle to estimate theoretical steering angle when Tractor-Trailer negotiate any turn. Steering linkage geometry has been conceptualised, kinematically modelled and analysed by using ADAMS. Equations developed for theoretical steering angles are incorporated in ADAMS as run time functions. The difference in theoretical steering angles and angles obtained from kinematic analysis of linkage geometry are defined as steering errors. These errors are obtained from the kinematic analysis for all the axles of trailer for entire range of turning. Design of Experiment (DOE) has been carried out to minimize the steering error. The model has been made parametric to carry out DOE and also to incorporate any design changes with minimum modelling time. The mathematical equations are validated and steering error obtained from the analysis is also validated with published literature. Physical prototype made and validation carried out with tested data.