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36th International Symposium on Robotics(ISR2005) 2005 Nov.29-Dec.1 in
Tokyo
ROTANPO（Robotic Travel Aid Non Profit Organization）
Report at International Symposium
Next-Generation Intelligent Wheelchair as Developed by ROTA
Hideo Mori, Takateru Nakata
ROTA CO., Ltd.
Takeda4-3-11, Kofu 400-8511
(forest, takateru)@kaede.clab.yamanashi.ac.jp
Youichi Kamiyama
Graduate School of Engineering, Master’s course of E.E.
University of Yamanashi
Takeda4-3-11, Kofu 400-8511
The goal of the development of Next-Generation Intelligent Wheelchair is to provide an autonomous wheelchair for use by visually impaired or cerebrovascular disordered people who cannot walk all by themselves. The ROTA’s wheelchair is a motored vehicle equipped with a video camera, two units of range sensor and a computer. A user sits on the wheelchair, then puts in the starting-point number and the destination number as prepared on a pre-recorded route along which the wheelchair runs. In outdoor operations, the wheelchair detects sign patterns on the route such as road boundaries, tactile blocks and crossing marks, and moves along the route. In indoor operations, the sign patterns are corridors and walls. When the wheelchair has detected an obstacle, it immediately stops and waits at that point during a preset period of time. If the obstacle has stayed through the preset period of time, the wheelchair moves around the obstacle. QR codes are set at significant points such as entrances, elevator doors and the corners so that the wheelchair can verify the current location of itself.
1. INTRODUCTION
NEDO (The New Energy and Industrial Technology Development Organization), in its project of Practical Application of Next-Generation Robots, openly called for ??five types of robots which were to participate in demonstration at The 2005 World Exposition (EXPO 2005). One of the called types was Next-Generation Intelligent Wheelchair robot; for which adopted was the wheelchair on a cooperative project by AISHIN SEIKI Co., Ltd. and FUJITSU Ltd. The ROTA’s wheelchair (by ROTA Co., Ltd.) was not adopted because of the insufficient staff and funds on its project, but was separately picked up as one of the prototype robots in favor of ROTA’s technical excellence.?
The Aishin wheelchair, named TAO Aicle, moves along RF-ID embedded blocks, knowing its current location through GPS and obtaining necessary traffic signals through wireless-LAN.
2. SPECIFICATION REQUIREMENTS
2.1 Preliminary Experiments and Investigations
We carried out preliminary experiments and investigations in five institutions, viz. hospitals and nursing homes, using the wheelchair robots that we had developed in our prior project[1].
1) NARA-NISSEI-EDEN-NO-SONO Home: A high-class private home for the aged;approximately 500 rooms.
Traffic in the hallway is not heavy but leg-disabled persons with walking frames are often seen strolling on the carpeted floor.
2) YAMANASHI University Hospital: An advanced medical institution; approximately 600 sickbeds. Develops advanced medical technology. Educates and trains medical physicians.
3) ICHIMIYA-ONSEN Hospital: A small private rehabilitation hospital with hot-spring facilities; 123 sickbeds, 46 of which are specifically for rehabilitation patients.
4) Sante Vieue KAJIKAZAWA: One of the twenty eight nursing homes for the aged as established by Japan Social Insurance Incorporation; 100 sickbeds. Trains and encourages patients in considerably stable conditions so that they can lead their self-supporting lives and become able to go back home.
5) NANASAWA Light Home: A nursing home for visually impaired people; 20 rooms. Belongs to General Rehabilitation Center of KANAGAWA Prefecture. Has programs to step up quality of life on the needs of each visually impaired person: educates and trains them to improve capabilities of sensing, walking, communicating, etc.
2.2 Requirements for Specification
The results of the preliminary experiments and investigations revealed following requirements.
2.2.1 Requirements on Structure
1) A next-generation intelligent wheelchair must conform to the Physically Handicapped Persons Welfare Law, therefore should have the same basic construction as that of existing standard-type wheelchairs.
2) The video cameras and the range sensors should be located on the wheelchair so that they can avoid a contingent onset by the rider in the seat.
3) The bumper sensor should be located on the wheelchair so that it does not hinder rider’s getting on/off the seat. ?
2.2.2 Requirements on Controlling
4) Operations should be simple and easy for the rider to start and stop the wheelchair.
5) The controlling system should be able to meet variety of ?configurations --- passages, corridors, halls, etc. --- of routes.
6) Controlling should be stable in a corridor where sun-shining and shading may change conditions depending on the weather, season and time.
7) Controlling should be stable along a wall which is decorated with stripes.
8) Controlling should work in face of a door which is slowly opening away.
9) The wheelchair should be movable on a freight-elevator in a hospital.
10) The wheelchair should be able to know every current location.
2.2.3 Requirements on Avoidance of Obstacles
11) When the wheelchair has detected an obstacle, it should immediately stop and wait at that point during a preset period of time. If the obstacle has stayed through the preset period of time, the wheelchair should move around the obstacle.
12) The wheelchair should stop when it has detected other wheelchair.
13) The wheelchair should immediately stop when it has detected a side ditch or a downward stairway.
14) The wheelchair should stop in face of a closed glass door or a closed elevator door.
15) The wheelchair should come to a sharp stop when something has touched the bumper.
16) Any standard-type wheelchair can be modified to an intelligent wheelchair by installation of necessary equipment and controlling systems.
3. SYSTEM DESIGN?
3.1 Components
Fig.1 shows the system components of ROTA’s ?wheelchair.
1) The wheelchair is 1150mm in depth, 650mm in width, 1440mm in height and 37kg in weight. It is composed of a standard-type wheelchair, a driving unit, a computer system, a sensor system and a human interface.
2) The wheelchair was made by KAWAMURA Cycle Co., Ltd. on a partly ordered design.
3) The driving unit is AC22 (SUZUKI Motor Co.) which has 22-inch rear tires and a 24V-7.0Ah nickel-hydrogen battery. The wheelchair can run, with a full-charged battery, more than one hour at a speed of less than 4.5km/h.?
4) The computer system is composed of an image- processing computer, a built-in computer and an I/O box. The image-processing computer is Small Vision Processor of Renesas Northern Japan Semiconductor Inc. The built-in computer is Micro PC EES-3412 ( CPU: NS Geode GX1 300MHz, DRAM: 256MB, HDD:40GB) and is used for controlling and navigation. The I/O box is an interface between the built-in computer and peripheral devices such as sensors and driving units.
5) The sensor system is composed of a pan/tilt video camera, two units of range sensor, and a bumper sensor. The video camera, Sony EVI-D70, is ?fitted at the top of a 1440mm-high pole. The range sensor is PBS as manufactured by HOKUYOU Automatic Co., Ltd. This device collects data by scanning with LED light (λ=880nm), a 3000mm-radius semicircular area within 218° horizontal angle. One PBS unit is installed under the foot-rest plate to detect obstacles ahead. Another PBS unit is fitted on the pole at the height of 1400mm to detect ?a side ditch or a downward stairway. The bumper sensor is set within the shock-absorbing material on the foot-rest bar.
6) ?The human interface is composed of a ten-key pad and a speaker. Every visiting place is identified by the preset number. The ten-key pad is for putting in the number of the starting point and that of the destination. The speaker is fitted under the seat of the chair.
7) A well educated and trained operator selects the routes which are safe for both the user and the wheelchair. The operator manually moves the wheelchair along the selected routes so that the system components record those routes in the computer. The operator then divides the recorded routes into several paths with visual features, i.e. sign patterns and landmarks. Every set of the path-data includes locations of the path terminals, sign patterns, and landmarks along the path. Such edited data are then stored in the computer data-base system.
3.2 Functions and Operations
Fig.2 illustrates exemplified functions of the wheelchair.
1) Booting up: The user takes seat on the wheelchair at a starting point, then turns on the Key switch. After two minutes of preparation, the wheelchair says, “Touch the starting-point number and the destination number.” On recognition of ?the numbers touched in, the wheelchair detects a QR code on the wall and verifies its starting point. Then it tells: “Press the Start/Stop button.” 2) Locomotion: The wheelchair moves at a pre-set speed between 1km/h and 4km/h. It can run for about one hour with a full-charged battery. The battery should be recharged after every one-hour use.
3) Normal start/stop: The wheelchair stats or stops on every pressing of the Start/Stop button.
4) Emergency stop: When the bumper sensor has touched something or when the rider has pressed the Emergency button, the wheelchair stops immediately within 33cm traveled distance at the speed of 3km/h, within 61cm at 4km/h.
5) QR codes: QR codes are used to tell the current location of the wheelchair or to tell whether a facing door is open or closed. The image-processing system not only identifies the QR code but also detects the distance and the orientation toward the code. The QR-code cell has to be greater than 2 pixels in the video image to ensure correct identification. For instance, an A4-size QR code is identifiable with a 45-degree wide-angle lens at 2m or less distance away.
6) Hindrance by an obstacle: When the range sensor has detected an obstacle at 2.5m ～1.5 m ahead, the wheelchair slows down to 2/3 in speed and sounds “PING-PONG”. When the obstacle is seen in 1.5m ? 0.75m ahead, the wheelchair slows down to 1/3 in speed and sounds “PING-PONG PING-PONG”. When the obstacle has come within 0.75m distance, the wheelchair stops and repeats sounding “PING-PONG PING-PONG PING-PONG …”.
7) Avoidance of the obstacle: If the obstacle does not disappear within a preset period of time (normally 5 seconds) the wheelchair says, “I will avoid something in my way. Press the Backward Moving button.” When the button has been pressed, the wheelchair moves 0.7m backward and stops; then the range sensor scans and collects data in front of the wheelchair. If the sensor finds a free space beside the obstacle, the wheelchair moves forward through the space, passes round the obstacle, then takes the originally preset path.
4. DEMONSTRATION AT EXPO 2005
ROTA’s Next-Generation Intelligent Wheelchairs were demonstrated under a 8m×8m tent settled outside of Morizo Kiccoro Messe. The wheelchair moved from Starting-point to Destination, see Fig.3, on a predetermined rectangular course which was defined with rows of white flowerpots. Three QR codes, sized 20cm×20cm, were prepared; oneof them was meant for a Restaurant, other two were for a Toilet and a Telephone, respectively. One of those QR codes was set at the Starting-point and other two codes were distributed to the selected corners in the course.
In an attempt to show our wheelchair’s versatility, a switchback operation was performed at each corner as shown in Fig.4. The backward traveled distance was 70cm in this operation.
4.1 Participants to the Demonstration
We used three wheelchairs: two of them were for participants’ trial riding and one for a spare machine. The wheelchair took six minutes to complete moving on the demonstration course. A one hour or a half-hour period was given to one session of the demonstration and six sessions were performed per day. Total 286 participants experienced riding on the wheelchair: 20 handicapped people, 67 senior citizens, 81 healthy adults, 85 school children and 33 infants. For the infants and most of the school children, the wheelchair was nothing but an amusement cart.?
4.2 Technical Outcomes
1) Battery power supply: We had eight Nickel-Hydrogen batteries and chargers at the demonstration site; we found that six batteries were sufficient to work the demonstration for five hours.
2) Electrical breakdown: On one occasion, USB-RS232C converter failed, then was replaced with a new unit. This incident lost four hours of demonstration time.
?3) Locomotion error: In the early period of demonstration, the wheelchair often suffered from unaccountable errors in locomotion and touched the flowerpots. After some experiments and observations the causes of the errors were found to be (a) Unbalanced pressures of air in the tires between the left and the right wheels, hence unequal wheel-diameters, (b) Unexpected slippage of the wheels on the paved floor wetted with blown-in rain, and (c) A gyro error caused by incomplete halting-state of the wheelchair during the gyro-initialization time.
4) Bumper sensor error: A strong kick on the bumper stopped the wheelchair as it should, but trapped the sensor in the shock-absorbing material. The incident prohibited the sensor from returning to its prepared-to-detect position before the shock-absorbing material was so deformed by hands to release the sensor.
4.3 Participants’ Positive Remarks
4.3.1 Handicapped people
1) “I am very interested in the demonstrated wheelchair. It will be useful for us.”
2) “I hope, as a parent of this disabled child, you improve the wheelchair and make it lighter in weight and equipped with a reclining seat.”
3) “I am interested in the automatic backward movement of the wheelchair.”
4) (A child) “I had no fear on the wheelchair. It stops smoothly. It is very nice.”
5) (Mother of the child) “The wheelchair will be useful in a hospital. I want you to improve it so that it has a simpler I/O Box and that the route-setting operation ?is easier.”
6) “I used a wheelchair for some time in the past after I met a traffic accident. At that time I could not go anywhere without help by a nurse. This wheelchair may be useful to a self-supported life in a hospital. Also, after returning home from hospital, it was very difficult for me to go out for shopping all by myself on a wheelchair. This wheelchair may be helpful in such circumstances.”
7) “It is good to know that my wheelchair can be made into an intelligent wheelchair by adding the controlling system.”
8) “I would say I pay $5,000 for the wheelchair. ?If I should be disabled in a way whatsoever and so in need of the wheelchair, I might feel $10,000 is yet reasonable.” We heard some more remarks of similar context.
4.3.2 Visually impaired people
1) “I want to use the wheelchair for my six-year old sight-impaired daughter. When will it become available for me to buy and use it?”
2) “The wheelchair is something like a guide dog. I hope that its navigation system is improved further so that it can take me really ‘anywhere’ I want.
3) “I have problems in one eye, and have concerns about my future. The low speed of the wheelchair makes me feel safe.”
4.3.3 Senior or middle-aged citizens
1) “With the wheelchair I can go anywhere at anytime I want without help of a nurse. It makes me free from mental burden.
2) “I will tell my friend about the wheelchair.”
3) “I take care of my eighty-six year old parent. The wheelchair seems to be useful for that care.”
4) “The wheelchair will be needed more and more in the near future as the population of the aged leg-disabled people will increase in Japan.”
4.3.4 Wheelchair rider
“You often make mistakes in assisting wheelchair riders. I feel the wheelchair itself is more reliable than humans.”
4.3.5 Healthy Adults
1) “My mother is now bed-ridden. The wheelchair with a dialogue interface will be useful for her to go anywhere she wants.”
2) “The rider will feel safe hearing the voice guidance about the coming action of the wheelchair”
3) “I was much impressed when I saw that the wheelchair stops in front of a standing person.”
4.4 Participants’ Negative Remarks
4.4.1 Wheelchair assistant
“This wheelchair takes a very long time to read and identify a QR code, also to complete a switchback operation. It is important to minimize such added time.”
We heard some more remarks of similar context.
4.5 Participants’ Comments on Problems
1) Speaker: The speaker is now fitted under the seat of the chair; often difficult to hear what it says. It should be fitted at somewhere closer to the ears of the rider. This problem was most frequently pointed out.
2) Rear-view mirror: A rear-view mirror should be set up at somewhere near the top of the pole so that the wheelchair can watch the passage behind it while moving backward.
3) Speed: The speed of the wheelchair should be changeable while moving by the rider’s control.
4) Voice guidance: The wheelchair tells only “I turn to the right” or “I turn to the left” regardless of the purpose of that turning which may mean avoiding an obstacle, cornering, ?etc. Such purposes should be made clear in the voice so that a visually impaired rider ?may know what is meant in the movement.
5) Backward sensing: In order to control backward moving, an additional sensor is necessary to detect backward obstacles.
6) Basket: A shopping basket should be attached at the rear side of the wheelchair.
7) Steering wheel: Aged persons are more familiar with a steering wheel than an I/O-box?to control a vehicle. It might be desirable to allow the user to select a steering wheel or an I/O-box?to control the wheelchair.
8) ?Waterproof: The wheelchair should be waterproof in order to be safe against light rains, fruit-juice droppings etc. More desirable is a wheelchair that can be used near a bathtub tolerating splash of water and high humidity.
9) Fine-tuning of locomotion: In a toilet, fine-tuning of locomotion is required to set the wheelchair on a right position. Such fine-tuning should be operable by the rider.
10) Handrails: Handrails are necessary on the wheelchair to prevent riders from falling down or other accidents while getting-on and -off the wheelchair.
5. CONCLUSION
In the demonstration of Next-Generation Intelligent Wheelchair at EXPO 2005, visually impaired people, physically disabled people, their parents, senior citizens and healthy adults experienced riding ?on the wheelchair. Most of those participants had positive impressions and told us that the demonstrated wheelchair would be useful to handicapped people in various circumstances. Some incumbent riders of motored wheelchairs expressed their negative impressions that the demonstrated wheelchair moved slowly and that it took time to identify QR codes.
The participants suggested to us the points to be improved. Most of the improvements will be materialized without much difficulty.
The eleven-day demonstration has given us confidence in usefulness, reliability and robustness of ROTA’s wheelchair.
We plan to test the performances further in varied environments at the hospitals and the nursing homes mentioned above.
We think the problems most difficult to solve consist in social acceptance of the wheelchair. It is necessary to amend the existing traffic regulations and to modify present nursing-care systems.
REFERENCES
[1] H.mori et.al. “The Mat
ching Fund Project for Practical Use of Robotic Travel Aid for the Visually Impaired”, Advanced Robotics, Vol.18,No.5,pp.453-472,2004
Hideo Mori
ROTA CO., Ltd.
Takeda4-3-11, Kofu 400-8511
phone & facsimile(nighttime) 0551-25-3929 055-220-8637(daytime)
Email: mori-rota@hb.tp1.jp
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