Evolving Controllers for a Transformable Wheel Mobile Robot

Abstract

Unmanned ground vehicles (UGVs) are well suited to tasks that are either too dangerous or too monotonous for people. For example, UGVs can traverse arduous terrain in search of disaster victims. However, it is difficult to design these systems so that they perform well in a variety of different environments. In this study, we evolve controllers and physical characteristics of a UGV with transformable wheels to improve its mobility in a simulated environment. The UGV’s mission is to visit a sequence of coordinates while automatically handling obstacles of varying sizes by extending wheel struts radially outward from the center of each wheel. Evolved finite state machines (FSMs) and artificial neural networks (ANNs) are compared, and a set of controller design principles are gathered from analyzing these experiments. Results show similar performance between FSM and ANN controllers but differing strategies. Finally, we show that a UGV’s controller and physical characteristics can be effectively chosen by examining results from evolutionary optimization.

$\mathbf{\alpha }$-WaLTR: Adaptive Wheel-and-Leg Transformable Robot for Versatile Multiterrain Locomotion

“…A similar mechanism was also applied to origami wheels [28], [29]. Another strategy adopts stick-shaped legs, hidden in the wheel or extended out [30], [31]. A wheel comprised of two halfcircle legs can be either folded into a semicircular wheel [32], [33] or deviated radially, forming two legs [34], [35].…”

Design and Analysis of Transformable Wheel with Pivoting-Head Mechanism

“…However, they tend to be designed to adapt to a specific terrain condition, that is, they sometimes encounter a situation they are not suited for, especially for varying complex terrain combined with flat road, bumps, slope, steps etc. Therefore, in order to cope with the above scenarios, transformable wheels have been studied recently which can transform themselves to adapt to the variety of terrain [9][10][11].…”

“…Clark et al [9] presented a transformable wheel, Adabot, which can smoothly be converted from a round wheel, to a wheel with tire studs, to a legged wheel. Wheel transformations are performed by extending wheel struts radially outward from the center of the wheel.…”

“…However, the transformable wheels proposed in these previous works have the following problems: The transformable wheel [9][10][11] that is based on the round wheel adopts the common method of increasing the wheel diameter to improve the obstacle surmounting performance. At the same time, the shape of the outer side of the round wheel is changed through deformation to show the characteristics of "legs" to further increase obstacle surmounting performance.…”

Motion Kinematics Analysis of a Horse Inspired Terrain-Adaptive Unmanned Vehicle With Four Hydraulic Swing Arms

“…For the legged ATV, it has good adaptability performance on rugged terrain with its discrete mechanism and more degrees of freedom [12]. However, the speed of legged ATV is limited and the frequent impacts of leg and the ground reduce energy efficiency [13]. It is interesting to combine the excellent adaptability and the high speed of legged ATV with good energy efficiency of wheeled ATV.…”