Juan Urbano

Frequency shape control of omni-directional wheelchair to increase user's comfort

An omni-directional wheelchair is highly maneuverable in narrow or crowded areas such as residences, offices and hospitals. However, with the increase in the degrees of freedom accompanying omni-directional wheelchairs, it has become more important than in the past to develop a smooth and vibrationless motion control system. This paper presents a novel motion control method for an omni-directional wheelchair considering the suppression of vibration of both the wheelchair and the user. In the proposed control system, the vibration of the wheelchair is suppressed by notching the frequency characteristics at the natural frequency of both the wheelchair and humans organs. The designed controller satisfies various control specifications such as settling time and stability by using feedback from only the wheelchairs position data. The effectiveness of the proposed system is evaluated by the output signal of a sensor attached to the wheelchair and by a descriptive inspection of several users.

Velocity control of an omni-directional wheelchair considering user's comfort by suppressing vibration

In this paper, riding comfort of an omnidirectional wheelchair (OMW) driven by joystick is studied for the case when OMW moves in X direction, Y direction, or in a slanting direction. In order to achieve the comfort driving specific spectrum elements such as natural frequency of OMW and discomfort frequency of human organs are suppressed. In order to evaluate the comfort, a human model which considers human upper body composed of two parts: torso and head, has been developed and used in order to test the effectiveness of the proposed approach. Experimental results of velocity control are shown.

Impedance control for safety and comfortable navigation of an omni-directional mobile wheelchair

The present paper gives a haptic feedback control of a holonomic omni-directional mobile wheelchair (OMW) with a haptic joystick for the operation of disable people or elderly people considering not only the navigation task but also users comfort and safety. In the present research a haptic joystick was designed and applied with being maneuverable for users and free of joysticks vibrations. If an obstacle is detected in the direction of movement, the impedance of the joystick in this direction is changed. Namely, the closer the obstacle is the bigger the impedance value becomes. By this function, users spontaneously understand that they are in risk of obstacle collision and then users can change the direction of movement, by their decision, in order to avoid it. Furthermore, for the command input by human joystick operation, velocity control of OMW is executed by means of frequency shaped control to achieve the comfort drive for users. The proposed approach is thought to be reasonable as a man-machine existing control system.

Power assist system for omni-directional transport wheelchair using fuzzy reasoning

In the aged society, it has become more important than in the past to develop technologies for human assist. In this paper, a power assist system for the attendant of an omni-directional transport wheelchair is developed. The input force of the attendant is measured using a force sensor attached to the handle of the wheelchair. The desired motion of the wheelchair is estimated from the output signal of the force sensor using fuzzy reasoning. Then, it is transmitted to four motors of the wheelchair to make it move toward desired direction. The effectiveness of the proposed method is examined by experiments.

NAVIGATION WITH COMFORT OF OMNI-DIRECTIONAL WHEELCHAIR DRIVEN BY JOYSTICK

Abstract Wheelchairs are the most common used device in order to allow elderly and handicapped people more independence and greater interaction in their communities. The purpose of this research is to control the motion of an Omnidirectional Mobile Wheelchair (OMW) while considering users comfort. A human model is built for evaluating the proposed controller, considering that the human upper body consists of two rigid parts: head and torso. The proposed controller can not only control OMW fast and effectively but can also improve users’ comfort greatly by suppressing vibration caused mainly by inappropriate acceleration while driving.

Development of a Human-Friendly Omnidirectional Wheelchair with Safety, Comfort and Operability Using a Smart Interface

A variety of wheelchairs with different options and special add-on features have been developed to meet a wide range of needs (Pin & Killough, 1994), (Wada & Asada, 1999), (West & Asada, 1992). In order to satisfy the demand for higher mobility, designers have created new driving concepts such as omni-directional movement which allows any combination of forward, sideways, and rotational movement, thus ensuring users much more freedom and safety in wide or narrow spaces. Autonomous electric wheelchairs are very useful for people who cannot move their upper bodies freely. However, these wheelchairs need to be fitted with a central control unit and high-level sensors capable of realizing complex navigation and obstacle avoidance tasks, based on a description of the environment and final goals marked out by those sensors. Since autonomous wheelchairs can function well only in special environments, this mode greatly limits the users freedom. In order to offer users with a higher degree of independence, the user-controlled movement mode, or semi-autonomous mode, which is operated under absolute user control by an input device such as a joystick, switch, monitor, etc., has been developed. The main difference between autonomous and semi-autonomous systems is that in semi-autonomous systems users interact in real time to perform certain tasks in dynamic environments. Under user control, the wheelchair can go wherever the user wants it to. Therefore, this mode provides a high degree of user independence. However, it is necessary to keep in mind that some elderly people or handicapped people can not use their arms due to weakness or injury. These people need the help of an attendant. In developed countries in which the number of young people is declining yearly, some healthy elderly people are taking care of other elder or handicapped people. For these attendants, a system that helps them to push the wheelchair and its occupant would be very convenient.

Skill Assist Neuro-Fuzzy Control of Omni-directional Wheelchair for Attendants Considering Rotation Center of Vehicle

Abstract For improving the operability of an omni-directional wheelchair provided with a power assist system, the system must be able to adapt to the individual characteristics of the many different attendants that will use it. For achieving this purpose, an innovative human-interface using a touch panel that provides easy input and feedback information in real time of the operation of a power-assisted wheelchair was developed. The system was tested experimentally with many different attendants and the results show that in addition to providing a human friendly interface by using the touch panel system with a monitor, the system can successfully adapt to the particular habits of the attendants. Furthermore, control of the rotation center of the OMW is proposed by making use of the OMWs potential advantage and coordination transformation.

Neuro-fuzzy control of a power assist Omni-directional Wheelchair to enhance maneuverability

For helping attendants of handicapped people and elderly people, a power assist system has been added to an omni-directional wheelchair (OMW). With this addition it is possible for the attendants to deal with heavy loads, but there is a problem of operability when the attendants want to move the OMW laterally or rotate around OMWs gravity center (CG). In this paper, for solving this problem, a fuzzy reasoning method has been proposed for estimating the navigation direction according to the force added by the attendants to the handgrips of the handle of the OMW. A neuro-fuzzy system (ANFIS) is used for the tuning of the membership functions of the fuzzy system according to each attendants characteristics, by using the input data of the attendants