This paper describes about improvements in the mobility of a stair climbable mobile robot on a step-field. A step-field, standardized by the National Institute of Standards and Technology (NIST), is a simulated artificial rough terrain used for testing rescue robots. Its use was popularized worldwide in the RoboCup Rescue contest, but a method for evaluating test results from it has yet to be established sufficiently. The author of this paper attempts to evaluate the mobility of stair climbable mobile robots on step-fields. A novel method using the 2 parameters of yaw-angle error and lateral position error is proposed. Two actual robots, SMART-IV type A and SMART-IV type B, are constructed and evaluated on small step-fields. The test results indicate that both robots can traverse the step-field under some appropriate conditions, but a comparison of the results indicates that the proposed design changes may be declared an improvement of the robot.

Improvement of the Mobility on the Step-Field for a Stair Climbable Robot with Passive Crawlers

In this chapter, we introduce a stair-climbing robot developed in our laboratory This robot consists basically of two body parts connected by springs, and hops as a result of the vibration of a two-degrees-of-freedom (2-DOF) system The excellent combination between the frequencies of the robotic body vibration and the tread-riser interval of stairs enables a small and simple robot fast stair climbing, soft landing, and energy saving In an attempt to give the robot mobility in an environment such as an office building having steps and stairs, various mechanisms have been proposed and developed Each one of which has different characteristics For example, wheel-based robots are very simple in terms of both mechanical design and control, and they can travel quickly and stably But their size tends to be big for climbing stairs, as they cannot surmount a riser higher than their wheel radius On the other hand, although crawler-type robots can climb over a riser higher than a wheel-based robot, they are slow and noisy Typical examples of crawler-type robots are TAQT (Hirose et al, 1992) that can carry a human and Kenaf (Yoshida et al, 2007) for rescue operations Legged robots, especially humanoid ones, are well suited for climbing stairs, but require many DOFs and complex control Honda’s ASIMO (ASIMO OFFICIAL SITE), AIST’s HRP (Harada et al, 2006) and Waseda University’s legged robot (Sugahara et al, 2007) are good examples In addition, the hybrids of these types have been proposed and have improved upon mutual demerits Chari-be (Nakajima et al, 2004), with two wheels and four legs, travels quickly on its wheels over flat terrain, and climbs using its legs in rough terrain such as a step and stairs A biped-type robot with a wheel at the tip of its legs (Matsumoto et al, 1999) climbs stairs smoothly RHex (Altendorfer et al, 2001) has six compliant rotary legs and travels speedily not only up and down stairs, but also even uncertain terrain such as a swamp Moreover, modular robots such as an articulated snakelike robot and special mechanisms for stairs have also been proposed Yim’s snake-like robot (Yim et al, 2001) climbs stairs, transforming its own loop form into a stair shape These excellent mechanisms have improved the manoeuvrability of the robot for rough terrain, but as most are general-purpose robots for rough terrain, a more specialized mechanism must be developed if we focus solely on stair-climbing ability in an office building 3

/pdf/a-wheel-based-stair-climbing-robot-with-a-hopping-mechanism-ibwinp0rz0.pdf

A Wheel-based Stair-climbing Robot with a Hopping Mechanism

LEVO: Mobile Robotic Platform Using Wheel-Mode Switching Primitives

In recent years many researchers are trying to combine wheeled movement with legged movement or hopping movement to strengthen the robots adaptability to environment. Hybrid robots are playing a more and more important role in our modern life. However, their controls are mostly complicated. So in this paper we present a new solution for the wheeled hopping robot. Based on the mechanical design, this robot has two movement modes: wheeled and hopping movement mode. While the center of gravity of the mechanism is under the wheels center, the wheeled hopping robot which is like a tumbler can keep its stability even when the wheels' velocity is zero. In this paper, we firstly introduce the description and design of the wheeled hopping robot. Then we explain how to choose the robot parameters and lastly we describe, how the robot through hopping, successfully traverses obstacles and ditches.

Design of a new solution for the wheeled hopping robot

The paper presents an innovative design for a wheeled hopping robot. Our main objective was to obtain a stable and efficient robot, which can jump over obstacles and has the ability to reach a certain ledge. The innovative design of our robot has the capability to jump to a certain distance even with a zero initial velocity provided by the wheels movement. Also, we took into consideration the wind speed which can prevent our robot to reach the desired destination, and compensated with an initial velocity on the direction of movement. For testing we designed a simulation which had as inputs different initial conditions to test and present the jumping capability of our robot in different jumping conditions. In the end we provide a jump area which the robot can reach for certain initial conditions, so we can later chose the optimal one for reaching the target position.

Yusuke Saito

Papers

Wheel-Based Stair Climbing Robot with Hopping Mechanism – Demonstration of Continuous Stair Climbing Using Vibration –

A Wheel-based Stair-climbing Robot with a Hopping Mechanism