Empirical Study on Characteristics of Angled Spoke-Based Wheels on Granular Media

Abstract

In this study, the optimal shape of angled spoke-based wheels (ASWs) was designed to maximize the driving speed of a mobile robot with ASWs on granular media. As a lightweight search and rescue mobile robot, it is required to have a high driving speed to reach the disaster site quickly. When granular media behave as fluids, slippage occurs, and the mobile robot slows down compared with when the media behave similarly to a solid ground. There are no exact criteria to explain the behavior of granular media. Therefore, the Taguchi method and L 9 (3 4 ) orthogonal array were employed to empirically optimize the shape of the ASW. The design variables evaluated were the motor RPM, width-height proportion of the foot, radius of curvature, and toe angle of the foot. The size of the ocher balls was adopted as the user condition. An orthogonal array and signal-to-noise (S/N) ratio were used to analyze the validity of the design variables. The optimal design variables of the ASW were a motor RPM of 6000, width-height proportion of 3:7, radius of curvature of 1.0×h, and toe angle of 15deg. Verification experiments were performed to evaluate the improved driving speed of the ASW. The angular velocity of the ASW increases by 2.79% for φ 1 (mm) and 10.50% for φ 6 (mm). Therefore, an optimized ASW design is expected to improve the driving speed of a mobile robot with ASWs.

Slip considered path planning of a novel angled-spoke based robot in a terrain mixture of granular media and rigid support

“…It advantage with compacted size and agile locomotion from simple mechanism. Agility of locomotion in granular media was assured by optimizing configuration of foot 12 , and traversability in both granular media and rogod support have been verified 13 .

Figure 1 Configuration of DODO and angled spoke based wheels.

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“…The configuration of the ASW is based on the optimization results from previous studies 12 , 13 . Spokes with ASA material were covered with a 3 mm thick silicone (VytaFlex 60) material cover.…”