Experimental study and analysis of the wheels’ steering mechanics for planetary exploration wheeled mobile robots moving on deformable terrain

Abstract

Due to the requirements of challenging planetary exploration missions with wheeled mobile robots (WMRs), the driving mechanics of WMRs’ wheels moving on the deformable terrain has been researched intensively, but the mechanics of the wheels’ steering is lacking research. Systematic steering experiments were carried out using a single-wheel testbed for wheels moving on a lunar soil simulant with different radii, widths, lug heights, and lug numbers under different vertical loads. The influence of the eccentric distance and motion state, such as the steering motor’s angular velocity, steering angle, and initial wheel sinkage, were also studied. The experimental results are illustrated with plenty of figures and analyzed based on the preliminary steering mechanics model to draw conclusions. The steering resistance moment is caused by the lateral bulldoze stress and the shearing stress at the bottom of the wheel. The wheel sinkage and steering moment of resistance increase with an increase in steering angle, which could be fitted with exponential functions. The steering moment is the increasing function of the wheel sinkage, eccentric distance, vertical load, and wheel width. The conclusions, empirical models, and experimental data can be taken as references to the optimal design of a steering mechanism and the development/verification of a wheel’s steering mechanics model.

Characteristics of lug-soil interaction forces acting on a rotating lug in sandy soil

“…They proposed an equation for obtaining optimal grouser spaces that depend on geometric parameters (wheel radius, grouser height and spacing) and operating parameters (slip ratio and wheel sinkage). Ding et al experimentally confirmed the effects of the lug on the steering performance of the wheel [5].…”

Improved explicit-form equations for estimating dynamic wheel sinkage and compaction resistance on deformable terrain

“…Lateral slip sinkage is more severe for narrower wheels [36]. Table 2 Terrain property parameters [32]. Parameters k c , k φ , and n slightly differ from those in [32] as a negative value of k c was accepted without being set to zero.…”

“…Table 2 Terrain property parameters [32]. Parameters k c , k φ , and n slightly differ from those in [32] as a negative value of k c was accepted without being set to zero. The value of k φ ismuch larger than |k c |; the equivalent sinkage exponent K s = k c /b + k φ for wheels with smaller width is slightly larger.…”

Module-based structure design of wheeled mobile robot

“…Inotsume et al (2013) constructed the empirical studies for analysing and controlling the rovers to reconfigure themselves to adapt to the target terrain that involves sandy slopes. Ding et al (2013) established a deformable terrain based experimental platform for analysing and evaluating the rover wheel steering performance and mechanics laying background for optimal design of rover steering mechanisms. In addition, Michaud et al (2006) developed a rover chassis evaluation tool for the design, selection and optimisation of chassis for space exploration rovers.…”