Active Caster Research Articles

Study on an Add-on Type Electric Wheelchair Using Active Caster with the Differential Mechanism

This study developed an electric-powered manual wheelchair with a differential-drive active caster mounted at the rear of the wheelchair. The active caster has two axes: a caster wheel axis and a steering axis, and the coordinated control of these axes enables the wheel-mounted part to move in all directions. Conventional active casters have separate motors for the steering and wheel axes, and only the motor on the wheel axis operates when the wheelchair moves straight ahead, resulting in a low drive efficiency. Therefore, we developed a differential-drive-type active caster that uses a differential-drive mechanism. The differential-drive-type active caster uses the sum of the rotations of the two motors to move the steering axis, and the difference to move the wheel axis. Therefore, the two motors always operate, thus the drive efficiency is higher than that of a conventional type. However, we found that the two motors interfere with each other owing to their structure, making it difficult to stabilize the steering axis when speed increases. A control method was developed to solve this problem. Through verification experiments, we demonstrated the ability of the wheelchair to move at speeds over 6 km/h, the legal speed limit in Japan, the improved stability of the steering axis, and the accuracy of its omnidirectional movement. Additionally, to reduce the wobble that occurs when the electric-powered manual wheelchair moves straight ahead, we introduced a yaw-rate feedback to the joystick input system. The feedback was then verified in a lane-change experiment, confirming the wobble reduction.

Research on stable coordinated driving for active casters

Research on stable coordinated driving for active casters

Study on Self-Position Estimation and Control of Active Caster Type Omnidirectional Cart with Automatic / Manual Driving Modes

This paper presents the development of an active caster omnidirectional cart with manual/automatic modes. The proposed cart realizes holonomic and omnidirectional motions using dual-wheel active casters. Since the active caster has the same wheel structure as the passive caster, the active caster functions as a passive caster by disconnecting the drive shafts from the motors in the manual mode. In this mode, the cart can be moved by pushing and pulling by hand. Further, even in the manual mode, the movement of the cart by a human can be accurately recorded by measuring the rotation of the wheels and the steering shaft. In the proposed system, the operation of the cart manually moved is recorded, and playback of the motion by automatic driving is performed. This is a kind of teaching/playback system for carts. This function enables easy teaching of cart trajectories and accurate positions. This paper describes the mechanical design and control method of the omnidirectional cart, followed by the experimental results of the prototype omnidirectional cart.

Proposal of dolly with active caster available for consolidation

Proposal of dolly with active caster available for consolidation

Active casters for power transmission by monocytes (ACROBAT-S) control system and prototype experiment

Active casters for power transmission by monocytes (ACROBAT-S) control system and prototype experiment

Design of Robotic Vehicle for Personal Mobility with Electric-Driven Three-Wheels

In this paper, a robotic vehicle for a personal mobility with electric-driven three-wheels is proposed. Before designing the proposed robotics vehicle, omni-directional motions using special wheels, active caster wheels, and active steerable driving wheels are studied. For design of the proposed vehicle, we discuss about active steerable wheel design, and vehicle’s frame design. The omni-directional motion through the digital design exploration of the vehicle using active driving and steering wheel robot technology is examined. As the major mechanical components, an active steerable driving wheel, in-wheel motors, brakes, suspensions, and control systems are described. The design is established by rapid prototyping model of omni-directional motion. The steering geometry and control algorithm for the prototype of the proposed personal mobility are experimented.

ロッカーボギー機構を用いた全方向移動プラットフォームの開発

In connection with the super-aging society, there exists a growing interest in omnidirectional powered-wheelchairs that have superior mobility in a narrow space. An omnidirectional mobile robot composed of active dual-wheel caster assemblies can use general wheels such as rubber tires, so that it is easily applied to a powered wheelchair. This study is aimed at developing an omnidirectional mobile platform using active dualwheel caster assemblies in consideration of the run in a public road. An omnidirectional mobile platform using a rocker-bogie suspension system is proposed to improve the running ability, and several active dual-wheel caster modules are produced so as to be used in such a platform. In this paper, we give an overview of the active dual-wheel caster assemblies and the proposed robot, and describe the process of actual production of such modules and the associated experimental results.

Traveling Support of Wheelchair by Using Mobile Robot with Active Caster Opposed Dual-wheel

This paper presents the method of motion control for welfare mobile robot to realize traveling support of wheelchair user. The proposed welfare robot has both grasping function and mobile function. It is shown that by using active caster opposed dual-wheel as transportation device, wheelchair can move at arbitrary rotational radius and translatory velocity in keeping only grasping force control without positioning control by arms.

1P1-N06 全方向移動ロボットのプラグイン自動充電(特殊移動ロボット(1))

This paper presents plug-in automatic charge of omnidirectional mobile robot with active casters. In this system, a camera on the robot detects an outlet on wall and a plug on the robot is inserted in the outlet by only movement of robot. Because this system needs no stations for automatic charge of robot, this system provides space saving and improvement of efficiency for robot task. Outlet is detected by feature values of contours. Distance and angle of outlet are measured by geometric relation of object and picture. Furthermore, it is confirmed that camera enables robot to approach outlet by experiment. Hereafter, robot will be installed plug and experiment of plug-in automatic charge will be tried.

2A2-R05 すべりを伴う車両モデルに基づく全方向移動車両の制御(車輪型/クローラ型移動ロボット(2))

Vehicles with active-caster wheels which are a kind of omnidirectional mechanism using normal pneumatic tires can move arbitrary directions immediately and can move freely from noise and vibrations. The control of vehicles with active casters, however, is not enough studied. This study aims to establish a control method of personal vehicles with active casters with respect to high safety and attractions of amusement park, using independent drive and steering of active caster vehicles and dynamic model of vehicle. This paper formulates a model of vehicles. Movements of usual nonholonomic vehicles can be imitated by using an omnidirectional vehicle with active caster wheels.

1A2-G06 全方向車両のための動力学モデル(車輪型/クローラ型移動ロボット(2))

Vehicles with active-caster wheels which are a kind of omnidirectional mechanism using normal pneumatic tires can move arbitrary directions immediately and can move freely from noise and vibrations. The control of vehicles with active casters, however, is not enough studied. This study aims to establish a control method of personal vehicles with active casters with respect to high safety, using independent drive and steering of active caster vehicles and dynamic model of vehicle. As a first step, this paper formulates a model of vehicles. Movements of usual nonholonomic vehicles can be imitated by using an omnidirectional vehicle with active caster wheels.

Motion planning algorithms of an omni-directional mobile robot with active caster wheels

This work deals with motion planning algorithms of an omni-directional mobile robot with active caster wheels. A typical problem occurred in the motion control of such omni-directional mobile robot, which has been identified through experimental experiences, is skidding of the mobile wheel. It sometimes results in uncertain rotation of the steering wheel. To cope with this problem, a motion planning algorithm which resolves the skidding problem and uncertain motions of the steering wheel is mainly investigated. For navigation of the mobile robot, the posture of the omni-directional mobile robot is initially calculated using the odometry information. Then, the accuracy of the mobile robot's odometry is measured through comparison of the odometry information and the external sensor measurement. Finally, for successful navigation of the mobile robot, a motion planning algorithm that employs kinematic redundancy resolution method is proposed. Through simulations and experimentation, the feasibility of proposed algorithms was verified.

1P1-I07 アクティブキャスタを用いた全方向移動車両の制御(車輪型/クローラ型移動ロボット)

Vehicles with active-caster wheels which are a kind of omnidirectional mechanism using normal pneumatic tires can move arbitrary directions immediately and can move freely from noise and vibrations. The control of vehicles with active casters, however, is not enough studied. This study aims to establish a control method of vehicles with active casters with respect to high safety, using independent drive and steering of active caster vehicles. As a first step, this paper formulates a model of vehicles sideslips. Sideslips of usual nonholonomic vehicles are imitated using an omni-directional vehicle with active caster wheels.

구동 캐스터 바퀴를 이용한 전방향 모바일 로봇의 오도메트리와 내비게이션

This work deals with navigation of an omni-directional mobile robot with active caster wheels. Initially, the posture of the omni-directional mobile robot is calculated by using the odometry information. Next, the position accuracy of the mobile robot is measured through comparison of the odometry information and the external sensor measurement. Finally, for successful navigation of the mobile robot, a motion planning algorithm that employs kinematic redundancy resolution method is proposed. Through experiments for multiple obstacles and multiple moving obstacles, the feasibility of the proposed navigation algorithm was verified.

2P1-E16 分散アクチュエーションモジュールの開発 : あらゆる物体を移動ロボット化するアクティブ・キャスタ

2P1-E16 分散アクチュエーションモジュールの開発 : あらゆる物体を移動ロボット化するアクティブ・キャスタ

2A2-J05 配置自由な分散型アクチュエーションモジュールによる移動ロボットの実現(空間知)

In this paper, the Active Caster module for mobile platforms is described. The ubiquitous robot concept intend to realize more useful services in human life space by connecting distributed robot functions. As a distributed actuation module, the Active Caster has good characteristics of parallel driving actuator. This characteristics enables the Active Casters to be attached for various objects in human life space. The offset of the steering shaft which realizes more smooth movement of mobile platform is introduced. Moreover, Navi-Guide unit realizes more intuitive operation by human.

アクティブキャスタを用いた全方向移動ロボットのモデル化と制御

アクティブキャスタを用いた全方向移動ロボットのモデル化と制御

An Upper Drive-Active Dual-Wheel Caster Assembly and its Application for Constructing Holonomic and Omnidirectional Platform

A new mechanical upper-drive active dual-wheel caster assembly is developed and two types of holonomie and omnidirectional mobile robots which utilize this caster assembly are discussed in this paper. The new active caster assembly is equipped with two standard tires as its driving wheels. Two motors are mounted on the upper frame to drive each wheel independently through a series of gears and a belt. In this structure, the lower frame can steer arbitrary angles referred to the upper frame without any wiring problem, which inhibits practical application of the previous normal active dual-wheel caster assembly. The new active caster assembly is used to construct two types of holonomie and omnidirectional mobile robots. One is a conventional structure, and the other is a synchro-drive system. The kinematic models of the new active caster assembly and two types of mobile robots are derived and the characteristics of these two holonomic and omnidirectional mobile robots are illustrated by computer simulations using resolved velocity control.

Dynamic Model and Control for a Holonomic Omnidirectional Mobile Robot

In the recent past, mobile robots with high mobility have been developed actively. We have already proposed a holonomic and omnidirectional mobile robot using two active dual-wheel caster assemblies and also derived the kinematic models for the assembly and the mobile robot. This paper presents dynamic analysis and control for the mobile robot. The dynamic model has been derived based on the forces acting on the steering axis. Then a model-based resolved acceleration controller is constructed. The validity of the model and the effectiveness of the control system are confirmed by experiments using a prototype robot as well as simulations.

Construction of an Omnidirectional Mobile Robot Platform Based on Active Dual-Wheel Caster Mechanisms and Development of a Control Simulator

In this paper, we describe a new type of holonomic and omnidirectional mobile robot using two driving assemblies, one of which consists of two independent driving wheel mechanisms, just like an active dual-wheel caster with an offset steered axis. Kinematic models of the wheel mechanism and a mobile robot with two driving assemblies are derived, and these models are applied to construct a feedback control system based on a resolved velocity control system for the robot. The effectiveness of the presented method is illustrated by some computer simulations. The prototype of a mobile robot platform using two driving assemblies, which can be controlled by a personal computer or a 3D joystick manipulated by human, is constructed.