RT-Mover: a rough terrain mobile robot with a simple leg–wheel hybrid mechanism

Abstract

There is a strong demand in many fields for practical robots, such as a porter robot and a personal mobility robot, that can move over rough terrain while carrying a load horizontally. We have developed a robot, called RT-Mover, which shows adequate mobility performance on targeted types of rough terrain. It has four drivable wheels and two leg-like axles but only five active shafts. A strength of this robot is that it realizes both a leg mode and a wheel mode in a simple mechanism. In this paper, the mechanical design concept is discussed. With an emphasis on minimizing the number of drive shafts, a mechanism is designed for a four-wheeled mobile body that is widely used in practical locomotive machinery. Also, strategies for moving on rough terrain are proposed. The kinematics, stability, and control of RT-Mover are also described in detail. Some typical cases of rough terrain for wheel mode and leg mode are selected, and the robot's ability of locomotion is assessed through simulations and experiments. In each case, the robot is able to move over rough terrain while maintaining the horizontal orientation of its platform.

Comparison of Methods for Solving the Singular Configuration of a Wheel-Legged Mobile Robot

“…The wheellegged mobile robot is expected to move using wheel and leg mechanisms in miscellaneous environments. Therefore, there are related studies aiming at describing motion in various environments (12)- (15) . The wheel-legged mobile robot has two types of singular configuration.…”

The stable wheeled locomotion in low speed region for a wheel-legged mobile robot

“…Thus, there are many related studies that enhance such advantages of the wheel-legged mobile robot. For example, [1]- [3] have dealt with rovers working in the extreme environment such as uneven terrain, and [4]- [6] have applied robots to human support tasks in the human living environment.…”

Design and sensing of a flexible robot leg

“…The "six-leg-wheel" robot [18] consists of six wheels mounted on six swinging legs. The RT-mover [19] has four wheels mounted on rigid links in a sprawled posture. We finish this non-extensive review on the right side of the spectrum: the very successful NASA rover six wheeled design [20].…”