Omnidirectional Wheelchair Research Articles

Stabilization of an Omnidirectional Wheelchair with Statically Unstable Structure

Stabilization of an Omnidirectional Wheelchair with Statically Unstable Structure

Development of a Front-Wheel-Steering-Drive Dual-Wheel Caster Drive Mechanism for Omni-Directional Wheelchairs with High Step Climbing Performance

To enhance the step climbing performance of omni-directional wheelchair, we developed a front-wheel-steering-drive dual-wheel caster drive mechanism with rocker links and a differential mechanism. The dual-wheel caster drive mechanism has the advantage of simple structure and is suitable for wheelchair applications. Based on the motion characteristics of this mechanism, we have found that the step climbing performance can be improved by adopting a front-wheel-steering-drive mechanism. In addition, the rocker links and the differential mechanism are employed as a suspension mechanism to improve wheel ground contact. In this study, a 3D dynamics simulator was constructed to compare the performance of wheelchairs employing several mechanisms, including the proposed mechanism, in step climbing. Based on the motion characteristics of the dual-wheel caster drive mechanism, simulations were carried out under two conditions: steady state and transient state. Simulation results confirm that the proposed mechanism has high step climbing performance under both conditions. Furthermore, it is confirmed that the rocker links and differential mechanism work to improve step climbing performance when the step has an angle, which means that the two front wheels do not contact the step at the same time.

Experimental Implementation of Tracking Error Elimination for Omnidirectional Wheelchair Using PD-Fuzzy-P Controller

Wheelchairs have been an active-research problem in the maneuverability of mobile robots over the past decade. This study aims to develop the transportability of disabled people by controlling the motion of their smart wheelchairs. It presents a design of omnidirectional mobile robot where its wheels can be equipped to replace a conventional electric wheelchair in order to achieve flexible and reliable maneuverability. The decentralized algorithm is used for motion control of the omnidirectional robot, which deals with the three independent components of robot’s motion in the body coordinate frame: rotational moving, horizontal moving and vertical moving, which can be controlled separately with separated and different sub-controllers. The simulation analysis of the proposed study has been tested in authors’ previous work and two approaches of artificial intelligent-based controllers (PD-Fuzzy-P and GA-PID controllers) have been built in order to control optimally the maneuverability of such system. The results have showed that the PD-fuzzy-P controller has converged faster than the GA-PID controller and the robot has been able to track successfully the sharp curves’ maneuverability, such as a 90° corner in the squared shape and a U-turn in the rose shape with an error approaching zero. In this paper, the experimental tests of the PD-fuzzy-P controller are carried out on a real robot developed using EV3 Lego kit parts and Vicon motion capturing system is used to capture the robot’s motion in various trajectory scenarios in order to test the effectiveness of the proposed control design.

Development of 3-degree-of-freedom HMI for omnidirectional wheelchair typed mobile assistive robot using simple force detection mechanism

Development of 3-degree-of-freedom HMI for omnidirectional wheelchair typed mobile assistive robot using simple force detection mechanism

Decentralized Motion Control for Omnidirectional Wheelchair Tracking Error Elimination Using PD-Fuzzy-P and GA-PID Controllers.

The last decade observed a significant research effort directed towards maneuverability and safety of mobile robots such as smart wheelchairs. The conventional electric wheelchair can be equipped with motorized omnidirectional wheels and several sensors serving as inputs for the controller to achieve smooth, safe, and reliable maneuverability. This work uses the decentralized algorithm to control the motion of omnidirectional wheelchairs. In the body frame of the omnidirectional wheeled wheelchair there are three separated independent components of motion including rotational motion, horizontal motion, and vertical motion, which can be controlled separately. So, each component can have its different sub-controller with a minimum tracking error. The present work aims to enhance the mobility of wheelchair users by utilizing an application to control the motion of their attained/unattained smart wheelchairs, especially in narrow places and at hard detours such as 90˚ corners and U-turns, which improves the quality of life of disabled users by facilitating their wheelchairs’ maneuverability. Two approaches of artificial intelligent-based controllers (PD-Fuzzy-P and GA-PID controllers) are designed to optimally enhance the maneuverability of the system. MATLAB software is used to simulate the system and calculate the Mean Error (ME) and Mean Square Error (MSE) for various scenarios in both approaches, the results showed that the PD-Fuzzy-P controller has a faster convergence in trajectory tracking than the GA-PID controller. Therefore, the proposed system can find its application in many areas including transporting locomotor-based disabled individuals and geriatric people as well as automated guided vehicles.

Study of omnidirectional mobile electric wheelchair for handicapped children's early movement experience

Study of omnidirectional mobile electric wheelchair for handicapped children's early movement experience

Development of a Compact and Foldable Omni-directional Wheelchair Robot

Development of a Compact and Foldable Omni-directional Wheelchair Robot

Human Behavior Intention Estimation of Goal Instruction Based on Saliency Map in Gaze Controlled Teaching System for Omni-Directional Wheelchair

Human Behavior Intention Estimation of Goal Instruction Based on Saliency Map in Gaze Controlled Teaching System for Omni-Directional Wheelchair

Towards BCI-actuated smart wheelchair system

BackgroundElectroencephalogram-based brain–computer interfaces (BCIs) represent novel human machine interactive technology that allows people to communicate and interact with the external world without relying on their peripheral muscles and nervous system. Among BCI systems, brain-actuated wheelchairs are promising systems for the rehabilitation of severely motor disabled individuals who are unable to control a wheelchair by conventional interfaces. Previous related studies realized the easy use of brain-actuated wheelchairs that enable people to navigate the wheelchair through simple commands; however, these systems rely on offline calibration of the environment. Other systems do not rely on any prior knowledge; however, the control of the system is time consuming. In this paper, we have proposed an improved mobile platform structure equipped with an omnidirectional wheelchair, a lightweight robotic arm, a target recognition module and an auto-control module. Based on the you only look once (YOLO) algorithm, our system can, in real time, recognize and locate the targets in the environment, and the users confirm one target through a P300-based BCI. An expert system plans a proper solution for a specific target; for example, the planned solution for a door is opening the door and then passing through it, and the auto-control system then jointly controls the wheelchair and robotic arm to complete the operation. During the task execution, the target is also tracked by using an image tracking technique. Thus, we have formed an easy-to-use system that can provide accurate services to satisfy user requirements, and this system can accommodate different environments.ResultsTo validate and evaluate our system, an experiment simulating the daily application was performed. The tasks included the user driving the system closer to a walking man and having a conversation with him; going to another room through a door; and picking up a bottle of water on the desk and drinking water. Three patients (cerebral infarction; spinal injury; and stroke) and four healthy subjects participated in the test and all completed the tasks.ConclusionThis article presents a brain-actuated smart wheelchair system. The system is intelligent in that it provides efficient and considerate services for users. To test the system, three patients and four healthy subjects were recruited to participate in a test. The results demonstrate that the system works smartly and efficiently; with this system, users only need to issue small commands to get considerate services. This system is of significance for accelerating the application of BCIs in the practical environment, especially for patients who will use a BCI for rehabilitation applications.

Modeling and Kinematics Simulation of a Mecanum Wheel Platform in RecurDyn

The innovative method of modeling and kinematics simulation in RecurDyn are proposed, taking a Mecanum wheel platform(MWP) for omnidirectional wheelchair as research object. In order to study the motion characteristics and mobile performance of the MWP, the virtual prototype simulation model is established in SolidWorks, and virtual prototype simulation is carried out in RecurDyn. The experience of simulation for the MWP in RecurDyn is introduced, and the simulation steps and points for attention are described detailedly. The working states of the mobile system in real environment have been simulated through virtual simulation experiments. Four typical motion models including moving forward, moving laterally, moving laterally in the direction of 45°, and rotation have been simulated in RecurDyn. The simulation results exactly reflect the motion of the MWP. By comparing the simulation results with the theoretical results, there are acceptable errors that are relatively less overall in the simulation results. The simulation results can be used to predict the performance of the platform and evaluate the design rationality, and design quality can be improved according to the exposed problem. This paper can provide reference for the simulation of mobile platform by using RecurDyn.

Hand Gesture Recognition Based Omnidirectional Wheelchair Control Using IMU and EMG Sensors

This paper presents a hand gesture based control of an omnidirectional wheelchair using inertial measurement unit (IMU) and myoelectric units as wearable sensors. Seven common gestures are recognized and classified using shape based feature extraction and Dendogram Support Vector Machine (DSVM) classifier. The dynamic gestures are mapped to the omnidirectional motion commands to navigate the wheelchair. A single IMU is used to measure the wrist tilt angle and acceleration in three axis. EMG signals are extracted from two forearm muscles namely Extensor Carpi Radialis and Flexor Carpi Radialis and processed to provide Root Mean Square (RMS) signal. Initiation and termination of dynamic activities are based on autonomous identification of static to dynamic or dynamic to static transition by setting static thresholds on processed IMU and myoelectric sensor data. Classification involves recognizing the activity pattern based on periodic shape of trajectories of the triaxial wrist tilt angle and EMG-RMS from the two selected muscles. Second order Polynomial coefficients extracted from the sensor trajectory templates during specific dynamic activity cycles are used as features to classify dynamic activities. Classification algorithm and real time navigation of the wheelchair using the proposed algorithm has been tested by five healthy subjects. Classification accuracy of 94% was achieved by DSVM classifier on ‘k’ fold cross validation data of 5 users. Classification accuracy while operating the wheelchair was 90.5%.

Implementation and experimental evaluation of an omnidirectional wheelchair for sports and moving in rooms with narrow spaces

The aged tendency of population and rapid growth in the number of disabled people caused by diseases or injuries require to build wheelchairs with good performance. Also, the wheelchair should provide the user with many benefits, such as maintaining mobility, continuing or broadening community and social activities, conserving strength and energy, and enhancing quality of life. The wheelchair body must be compact enough and should be able to make different movements in order to have many applications. In this paper, we present the implementation and experimental evaluation of an omnidirectional wheelchair for sports and moving in rooms with narrow spaces. The experimental evaluation shows that the implemented wheelchair has a good behaviour and can be used for real applications.

Omnidirectional Assistive Wheelchair: Design and Control with Isometric Myoelectric Based Intention Classification

Smart electric wheelchairs are becoming a natural substitute of the conventional wheelchairs as an assitive device for geriatric population and patients suffering from mobility disorders. There is a demand for developing powered wheelchairs with intelligent control to suit wide range of application in the field of assistive technology. This paper deals with the development of a 4 wheeled omnidirectional wheelchair and its control using a myoelectric user intention interface. Developed system is driven by holonomic drive system, exploring greater maneuverability compared to conventional powered wheelchairs. Myoelectric signals from forearm muscles are processed to extract some features for seven different wheelchair motion namely forward, backward, left, right, clock-wise and anticlockwise turn and stop. A neural network classifier classifies the user intention and maps the intention to wheelchair motion. The developed system finds its direct application in transporting people with locomotor disability, geriatric population as well as an indoor navigation vehicle.

Velocity measurement for omni-directional intelligent wheelchair

This paper presents an optical flow-based novel technique to perceive the instant motion velocity of a smart wheelchair robot. The primary focus of this study is to determine the wheelchair’s ego-motion using a displacement field in temporally consecutive image pairs. In contrast to most previous approaches for estimating velocity, the proposed strategy has two main innovations. Firstly, the proposed tilted overlooking camera set-up instead of conventional downward-looking camera and the corresponding ego-motion model is presented for compact indoor mobile robots. Secondly, by virtue of the graphic processing unit-accelerated TV- L1 algorithm, which is coupled with motion priors-based pixel prediction, we are permitted to improve the accuracy and efficiency of the optical flow estimation significantly. In order to render our method more robust with respect to noise and outliers, we propose a quadratic motion model-based random sample consensus (RANSAC) refinement of flow fields. Advantages of our proposal are validated by real experimental results carried on our smart wheelchair platform and contrast evaluations conducted on Pioneer robot.

滑り込みシートを利用した移乗動作補助システムの構築

It is one of the significant problems for hospital patients to transfer from the bed to a wheelchair. This study focused on the transfer motion from the bed and developed assist system of transfer motion for the bed user, without lifting motion performed by the caregivers. Thin skin career sheet was inserted below the patient sitting on the bed side, and it was hanged on the cantilever chair equipped on the omnidirectional wheelchair. We propose a method to decrease the friction caused in the inserting the career sheet by changing the patients posture.

全方向車いすを利用したベッド支援システムの構築

全方向車いすを利用したベッド支援システムの構築

Obstacle Avoidance of Omnidirectional Intelligent Wheelchair Based on Multi-Sensors

As the number of handicapped people increases worldwidely, the role of electric wheelchair becomes important to enhance their mobility. In the relevant community, attention is mainly directed to how to solve the problems in motion control for the wheelchair users, and scarce reports have appeared concerning obstacle avoidance of wheelchair. In this paper, we present a new method of obstacle avoidance for omnidirectional intelligent wheelchair bases on multi-sensors information fusion. Distance information acquired from ultrasonic sensors and visual information acquired from monocular camera are combined together, in which optical flow method is employed to distinguish obstacles. Extensive experiments have been conducted in the laboratory. As shown in experimental results that, the developed omnidirectional intelligent wheelchair works correctly and effectively in obstacle avoidance.

3A1-O05 全方向車いすによる掲示物閲覧システムの構築(感覚・運動・計測(1))

3A1-O05 全方向車いすによる掲示物閲覧システムの構築(感覚・運動・計測(1))

2A1-T01 介護者との相対的位置関係を考慮した車椅子誘導法(人間機械協調)

In this paper, the aim of this research is navigation method of a wheelchair based on the relative position between a wheelchair and its caregiver. In order to realize the safe navigation, the sensors applied to both assistance grips of the wheelchair, then estimating caregiver's position from the sensors that power acts on. We suggest collision avoidance method and the switching of position between caregiver and wheelchair that considered the relative position relations of a wheelchair and its caregiver. Experimental results using Omni-directional Wheelchair showed the effectiveness of the proposed navigation method.

Web-based Customization and Motion Simulation of the Omni-directional Wheelchair

A wheelchair with omni-directional wheel is introduced in this article. Two kinds of omni-directional wheel, Mecanum wheel and Trans wheel, are illustrated and their motion principles were analyzed. Virtual Reality Modeling Language (VRML) is adopted to implement the real-time customization and motion simulation. In the real-time customization process, the color of some parts of the wheelchair can be altered, and the shape of components can also be replaced via the customization panel. By using this methods, the omni-directional movements such as longitu-dinal, lateral and rotary motion can be emulated via the simulation panel. In this way, clients can participate in the design and get a wheelchair according to their individual requirements, which will give them a deeper and more impressive feeling about the wheelchair’s special motion functions.