Naoaki Yonezawa

A novel stair-climbing wheelchair with transformable wheeled four-bar linkages

This paper describes the development of a novel multi-wheel stair-climbing wheelchair. The necessity for mobility aid technology for elderly and handicapped people that has “minimal invasiveness for use in an historical environment” is described. With this goal in mind, a prototype of a novel wheelchair having a stair-climbing function resulting from transformable wheeled four-bar linkages is proposed. The mechanical design, principle of operation and statics of the proposed mechanism are thoroughly illustrated. The basic performance of the proposed mechanism has been confirmed through experimental results.

A car transportation system using multiple mobile robots: iCART II

This paper proposes a new car transportation system, iCART II (intelligent Cooperative Autonomous Robot Transporters - type II), based on “a-robot-for-a-wheel” concept. A prototype system, MRWheel (a Mobile Robot for a Wheel), is designed and downsized less than the half of the conventional robot used in iCART (intelligent Cooperative Autonomous Robot Transporters). In general, it is very difficult for mobile robots such as MRWheel to move to desired positions without motion errors caused by slipping, etc. Therefore we propose a decentralized control algorithm for car transportation in coordination by using a leader-follower type multiple robot system. The proposed algorithm enables the followers to estimate and reduce the motion errors and then enables the robots to transport a car to a desired position, even if the motion errors occur. In addition, we discuss how the external force applied to each robot during transporting a car, such as an inertial and friction force, is shared among the robots, and we propose a model-based external force estimation and compensation method. The proposed control algorithm is applied to the system, and the results of car transportation experiment confirm its validity.

Car transportation system grasping two drive wheels

This article describes the concept of a novel car transportation system including two mobile robots with a lift mechanism for single wheel. The system lifts only two drive wheels of a front-wheel-drive vehicle or a rear-wheel-drive vehicle, and transports them. However, the system has nonholonomic constraints because all wheels of a vehicle are not lifted by the system. This article also describes a motion control method and a vehicles wheelbase estimate algorithm for the proposed system in order to maneuver the vehicle. The motion control method is based on control theory for a three-wheeled cycle system. On the other hand, the vehicles wheelbase estimate algorithm includes impedance control, and the system estimates the vehicles wheelbase from constraint forces during transporting the vehicle. Finally, two experiments show that the proposed system can maneuver the vehicle.

A Novel Stair-Climbing Wheelchair with Variable Configuration Four-Bar Linkage —Mechanism Design and Kinematics—

This paper describes the mechanism of a novel multi-wheel stair climbing wheelchair. The necessity of the mobility aid technology for elderly and handicapped people which has “Minimally-invasiveness for historical environment” are described, and with this goal, a novel multi-wheel stair climbing wheelchair with variable configuration four-bar linkage is proposed. Its mechanical design, principle of operation and kinematics are mainly illustrated.