Development of a computer input device for patients with tetraplegia
Introduction
It is difficult for patients with tetraplegia, whose level of spinal cord injury (SCI) is from C1 to C8, to work in an office because their range of motion in the upper limbs is limited. However, it has recently become easier for patients with tetraplegia to work in a home office by using a computer [1], [2]. In the field of rehabilitation medicine, occupational therapists (OTs) train patients to operate a computer as part of their rehabilitation. In this process, it is important for physicians and OTs to select a suitable computer input device for each patient.
For those disabled patients who are unable to use a standard mouse, researchers have developed various head-operated computer control devices [3], [4], [5]. Lau and O'Leary compared three of these computer interface devices—the Tongue Touch Keypad, the Head Master, and the mouth stick—in four people with severe physical disabilities, and reported that the level of accuracy was not significantly different among the three devices [6]. Bates proposed a device-level mapping of SCI levels to possible candidate input devices and thereby clarified the relation between SCI levels and the input devices [7]. For example, based on the device-level map, we can immediately ascertain that a patient with an SCI level of less than C4 cannot use a ball mouse or touch pad. Because SCI patients with an SCI level of C5 to C7 can move their upper limbs or hands, they can be trained to use computer input devices such as a ball mouse, track ball, or touch pad. It is necessary for the physicians and OTs to evaluate the computer-operation abilities and recommend a suitable computer input device for each SCI patient.
Keyboards and computer input devices such as a ball mouse, track ball, or touch pad are used for the operation of a computer. In the case of a keyboard, we can analyze a patient's ability to input data simply by using commercially available keyboard typing software. As to mouse cursor movement, several researchers have analyzed the ability of healthy participants to use a computer mouse [8], [9], [10]. However, no software is available to evaluate the ability of SCI patients to input computer data using a computer mouse.
In this study, we developed a software system that measures and evaluates the speed, accuracy, and extent of fatigue of patients with tetraplegia when they operate a computer using a ball mouse. Time is the most important parameter in evaluating the computer input ability, so we calculated three time parameters (the stopping period, moving period, and positioning period) after measurement. In addition, we developed a new computer input device by analyzing the locus of the mouse cursor when the patient performs a click operation test.
Section snippets
Measurement system
Fig. 1 shows a computer screen of the system that measures the computer input ability of patients with tetraplegia. The screen consists of a test area and a command area. A center target is displayed at the center of the test area, and a destination target is displayed in various places in the test area. Fig. 2 shows the algorithms of the measurement system. The choice of the subject such as a time test or cycle test, the number of repetitions, the target–appearance protocol, the appearance
New input device
It is desirable to develop a computer input device allowing patients with tetraplegia to perform computer operations within a reasonably short time period. Tetraplegic patients usually cannot perform fine computer operations when they move the devices and perform the click operations, and they sometimes hold computer input devices such as a ball mouse with both hands due to finger palsy caused by cervical spinal cord injury. Our new input device consists of a detecting box and a switch box, as
Experimental results
Fig. 11 shows the results of the mouse cursor locus when a healthy subject performed the click operation test using a ball mouse. It is clearly shown in the figure that the mouse cursor was moved linearly between the center target and the destination target.
Fig. 12 shows a experimental result of the mouse cursor locus when the patients with tetraplegia performed the click operation test using a ball mouse. Patient A and B are males (C5 SCI level). These loci are very different from the locus of
Conclusion
In the field of rehabilitation medicine, it is necessary for medical staff members to evaluate the computer input ability of patients with tetraplegia before training them to use a computer. We have therefore proposed a system for measuring and evaluating the computer input ability of patients with tetraplegia by calculating three time parameters (the stopping period, moving period, and positioning period). We believe that this measurement and evaluation system will be useful in the field of
Yoshio Tanimoto was born in 1961. He received his B.S. and M.S. degrees in electrical engineering from Okayama University, Okayama, Japan, in 1984 and 1986, respectively, and his Ph.D. degree in medical engineering from Hyogo University of Teacher Education, Katogun-Yashirocho, Hyogo, Japan, in 1999. In 1988, he joined the Kibikogen Rehabilitation Center for Employment Injuries, Jobogun-Kayocho, Okayama, Japan, where he became a Rehabilitation Engineer. His current interest is in the area of
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Cited by (0)
Yoshio Tanimoto was born in 1961. He received his B.S. and M.S. degrees in electrical engineering from Okayama University, Okayama, Japan, in 1984 and 1986, respectively, and his Ph.D. degree in medical engineering from Hyogo University of Teacher Education, Katogun-Yashirocho, Hyogo, Japan, in 1999. In 1988, he joined the Kibikogen Rehabilitation Center for Employment Injuries, Jobogun-Kayocho, Okayama, Japan, where he became a Rehabilitation Engineer. His current interest is in the area of rehabilitation engineering.
Yasuhiko Rokumyo was born in 1969. In 1987, he joined the Kibikogen Rehabilitation Center for Employment Injuries, Jobogun-Kayocho, Okayama, Japan, where he became a Rehabilitation Engineer. His current interest is in the area of rehabilitation engineering.
Kazunari Furusawa was born in 1963. He received his degree of Medical Science from University of Occupational and Environmental Health, Japan, in 1999. In 1999, he joined the Kibikogen Rehabilitation Center for Employment Injuries, Jobogun-Kayocho, Okayama, Japan. He has worked for this center in the rehabilitation medicine as a specialist in the medical rehabilitation of spinal cord injury.
Akihiro Tokuhiro was born in 1950. He received his degree of Medical Science from Okayama University, Okayama, Japan, in 1986. In 1987, he joined the Kibikogen Rehabilitation Center for Employment Injuries, Jobogun-Kayocho, Okayama, Japan. He has worked for this center in the rehabilitation medicine as a specialist in the medical rehabilitation of spinal cord injury.
Yasuo Suzuki was born in 1953. He received his B.A. and M.S. degrees in Applied Physics from Fukui University, Fukui, Japan in 1977 and 1979, respectively. He is currently a Biomedical Engineer at the Rousai Rehabilitation Engineering Center, Nagoya, Japan. His current research interests are dynamics of human movement and computer simulation of biomechanical systems.
Kenji Takami was born in 1943. He was employed as Rosai Rehabilitation Engineering Center in 1968. In 1963, he received training for half a year by VAPC in New York. He became a Licensed Prosthetist and Orthotist in 1986. His main researches are conformity evaluations of the prosthetic socket fitting. He is the acting director of the Japanese Society of Prosthetics and Orthotics. He is the research section chief in Rosai Rehabilitation Engineering Center, Komei, Minato-ku, Nagoya, Japan.
Hideki Yamamoto (M'73) was born in 1944. He received his B.S. degree in Electrical Engineering from Okayama University, Okayama, Japan, in 1966 and his Ph.D. degree in Electrical Engineering from Kyoto University, Kyoto, Japan, in 1983. He is currently a Professor in the Department of Education at Okayama University. His research interests include image processing and signal processing. Dr. Yamamoto is a member of the IEEE.