1995 VR Conference Proceedings

Go to previous article 
Go to next article 
Return to 1995 VR Table of Contents 


TEACHING MOTORIZED WHEELCHAIR OPERATION IN VIRTUAL REALITY

Dean P. Inman, Ph.D., Ken Loge, M.S., (presenters)
Oregon Research
Institute Virtual Reality Labs

The notion that childhood development is directly related to being able to independently explore one's environment is now widely accepted among social scientists, cognitive psychologists, and early childhood education specialists. A significant body of research has presented evidence over the last twenty-five years that self-locomotion experience plays an important role in the development of spatial perceptual abilities and cognition (Held & Hein, 1963; Bertenthal, Campos & Barrett, 1984; Adolph, Gibson & Eppler, 1990; Acredolo & Evans, 1980; Kermoian & Campos, 1988; Bertenthal & Bai, 1987; Horobin & Acredolo, 1986).

These skills form an integral part of how we interact with and utilize our environment. Spatial perception encompasses our ability to localize ourselves in space, depth perception, shape recognition, visually guided reaching, awareness of self- motion, as well as mapping and problem solving in multidimensional space (Wiley, 1982). This set of skills is necessary for many activities of daily life including mobility, vocational tasks, and independent social interaction. Children with motor dysfunction often do not have access to self-locomotion experience during early developmental years (birth to five years). For children whose motor dysfunction is severe, mobility experience can be delayed until young adulthood and beyond. The effects of this deficit in ability experience are severe. Fortunately, adaptive equipment is available to compensate for many physical limitations.

When mobility is limited, a motorized wheelchair is an excellent means by which children can achieve independent mobility. However, these wheelchairs are very expensive and it is unlikely that a motorized wheelchair will be purchased for a child unless it is clear in advance that s/he can use it effectively. Unfortunately, proficient use may require substantial training. This results in a "Catch-22" situation in which a child who needs a wheelchair with which to practice in order to acquire the necessary skills cannot obtain the wheelchair until a satisfactory level of proficiency has been achieved. Children who fail the initial evaluation are customarily denied access to motorized wheelchairs, and thus never experience the increased mobility that would have been afforded to them by a motorized wheelchair.

Even children whom already own motorized wheelchairs frequently lack the skills required to operate them safely in all environments. Enhancing their skill level requires intensive one-on-one training and close supervision to prevent mishaps and avoid injury. What is needed is a cost-effective means of training children to criterion without having to purchase motorized wheelchairs and/or without exposing them and others to physical danger during the training process. Virtual Reality, a newly emerging technology, is exciting in its implication for providing such training. This technology allows an individual to experience apparent movement and to explore lifelike environments. Its advantages for teaching complex motor skills are well documented. For example, Virtual Reality is often used in the training of airline pilots, astronauts and surgeons. It is a safe, cost- effective means of training sophisticated perceptual-motor skills.

The purpose of this project is to demonstrate and evaluate three Virtual Reality training programs designed to teach orthopedically impaired children to operate a motorized wheelchair safely in the natural environment. This project purports to demonstrate and evaluate a newly-emerging technology that may prove to be of great use in training children with severe physical disabilities. This technology will permit non ambulatory children to "move" freely and independently within diverse environments safely and with great realism. In so doing they will have a chance to enjoy and benefit from experiences that other children have routinely during their formative stages of development. With the advent of Virtual Reality technology, it is now possible to provide severely physically disabled children with a chance to explore, discover and to operate upon the physical environment so that it is possible for them to learn mobility skills and to develop cognitive strategies and perceptual abilities that can be learned only through self-initiated experience.

Training is accomplished by having children experience a series of three Virtual Reality Scenarios, which are sequenced in terms of difficulty and setting. The high degree of realism provided by these simulated experiences is achieved in two ways. First, reality is simulated by the physical configuration of the student's workstation. Second, reality is simulated via software, which generates a three- dimensional, stereoscopic, real-time image which is directly responsive to input from the student's joystick and head position. The physical configuration of the student's workstation is constructed to accommodate actual motorized wheelchairs of various sizes.

Children who already have their own wheelchairs use them during the training, while children who do not already own wheelchairs are provided one for use in the training settings. Several features have been incorporated into the workstation designed to mimic reality and thus enhance the transfer of skills to real-world settings. For example, a student's motorized wheelchair is placed on rollers supported by a metal frame approximately six inches off the ground. A small ramp enables the chair to be pushed up onto the platform and into position.

When in position the back wheels of the wheelchair rest on rollers that permit the wheels to rotate at normal speeds but which effectively prevent the chair from actually moving. Moreover, each back tire is situated on its own set of rollers that allows the right and left wheel to move independently of the other. Thus, when the joystick is moved to the left, which would normally cause the right rear wheel to turn faster than the left wheel, the apparatus permits differential axle speed to simulate the tactile, kinesthetic, and auditory feedback normally associated with making a left-hand turn. Also, the roller surfaces are slightly irregular which causes the chair to vibrate very slightly as it would normally do on surfaces such as sidewalks and low-pile carpeting. Under normal conditions when a motorized wheelchair is driven into a wall or an object, the driver feels a distinct bump and the chair's progress is halted.

In two out of the three training scenarios developed, the student learners have the opportunity to safely "crash" into objects or walls during the Virtual Reality training experience. To simulate the experience of crashing, the following features are built into the training platform. If the student learner crashes into an object or wall in the Virtual Reality training environment the visual sensation of movement is halted and a loud "crash" sound is heard. The student must then back up or move away from the obstacle before proceeding. In any crash situation the sound, feel, and immediacy of bumping into an object are quite realistic from the student driver's point of view. A major advantage of the Virtual Reality training experience is that there is no danger to the student driver or others during the driving education experience. Once the wheelchair is in place, the student driver is fitted with a helmet, through which the visual and auditory components of the VR training program are presented.

Inside the visor of the helmet are two video screens, one for each eye, through which a three-dimensional representation of a Virtual Reality World is presented. Also in the helmet are two earphones, one for each ear, through which a holophonic program can be presented to coincide with the visual images displayed in the visor. It should be noted, however, that the earphones in the helmet do not block out sound from the real world during the training process. Thus, it is possible to talk with students as they experience the Virtual Reality training scenarios and they are able to hear the motors of the wheelchair turning as they drive the rear wheels at different speeds.

The project's goals are to develop, demonstrate, and evaluate these three Virtual Reality training scenarios through which we hope to develop and/or enhance mobility skills in severely orthopedically impaired children. Each scenario is intended to provide learners with motivating mobility training experiences that allow them to function with more competence, independence, and safety in school and community settings. Scenarios One and Two are designed to promote independent exploration, discovery, cause and effect relationships, and visual memory (skills prerequisite to independent mobility that orthopedically impaired children often lack). These Virtual Realities are safe, highly entertaining situations where the student learner is allowed to roam freely during the discovery process. Scenario Three provides a more structured environment in the community and attempts to establish appropriate and safe street crossing skills using a crosswalk protected by a traffic light. Although many other scenarios are possible, we have limited the scope of our initial efforts to demonstrating and evaluating these three scenarios.

Scenario One:

Exploration of an Open Environment. In the first Virtual World, the child can explore a large, wall- less space that has no obstacles or impediments of any kind. The child is free to go forward and backward at any speed within the limits of the software and hardware. In addition, the child can choose to go in circles; large slow ones or very short tight ones. The floor consists of black and white tiles over which the child drives. This enhances the sensation of movement and speed as the child drives across the floor. In this Virtual World a child can experience the joy of independent mobility without fear and without constraints. It provides the basis upon which all other mobility skills are based.

Scenario Two:

Exploration and Discovery in a Closed Environment. The second Virtual World allows the student learner to explore an area that is approximately 2000 feet by 2000 feet. If the child runs into anything while moving about, the software simulates a real "crash" and additional sound effects appropriate to crashing are provided. Once an obstacle is struck, the chair must be moved right or left, away from the obstacle to continue. Also, it should be noted that the strength of the crash varies depending upon the speed that the chair is "moving" when it encounters the obstacle. This is to simulate accurately yet safely the consequences of moving in the real world. Scattered around this Virtual World are interactive obelisks that the child can discover while exploring the environment.

Each obelisk becomes activated when the child comes within two to three feet of it and responds to the activation in a unique fashion. The obelisks are designed to be highly entertaining, and we expect that each student will develop his/her personal favorites from among them. Some stations produce visual images that are very beautiful and dynamic, such as fractal flower patterns, spinning sculptures, and colorful architecture, with auditory programs of music or nature sounds. Two other facets of Scenario Two should be mentioned. First, the student driver always starts from the same position within the world. This way, the child learns that the exploration activities always begin from the same point of departure, permitting him or her to eventually memorize the world's configuration.

Second, the obelisks placed throughout the world will remain constant over time. Again, this permits children to create a visual memory of the world's layout and permits them to begin exploring from where they left off at the end of the previous session or to revisit sections of the world they found particularly amusing or interesting. This consistency enhances each child's ability to (a) memorize the world's features, (b) foster systematic and deliberate exploration of an environment, and (c) discover cause-and-effect relationships between volitional activity and activation or deactivation of devices or apparatuses that are contained within the environment. This type of simulated adventure is intended to foster a sense of curiosity, personal control, and an appreciation for the benefits of independent mobility. These subjective experiences are essential to a child's ability to benefit from more advanced mobility training because they form the motivation that drives the desire to learn mobility skills.

Scenario Three:

Initial Driver's Education for the Community. The third Virtual World consists of a street crossing scenario in the community. Obviously, the community environment is extremely complicated with a myriad of situations that could be targeted for training. We have chosen, however, to focus on developing and evaluating a street-crossing scenario because of its frequency and importance for safe mobility in the community. This VR program begins with the child on a sidewalk bordered by a lawn on one side and a two-way street with moving cars on the other. At a point 50 to 100 yards beyond the starting position, a crosswalk (complete with stop light and pedestrian crossing sign) is available.

On the other side of the street is another sidewalk perpendicular to the first one. The child's task is to (a) approach the crosswalk appropriately, (b) wait for the light and crosswalk sign to operate, signaling the cars to stop, (c) drive across the street within the boundaries of the crosswalk, and (d) negotiate the turn onto the opposite sidewalk. The child can go back and forth across the street as often as desired. It is important to recognize that Scenario Three, while being the closest approximation to the real world, is also the least interesting from the student driver's point of view. However, because we are most interested in evaluating the extent to which Virtual Reality training will permit a child to drive a motorized wheelchair safely and independently in the school and community environments, it is important that students practice and achieve competence in these practical situations. However, experience has taught us that motivation is very important in maintaining "best effort attempts" during the acquisition process. Therefore, our intention is to use Scenarios One and Two as reinforcers for making progress in Scenario Three.

In other words, we will use Scenarios One and Two initially to acquaint the students with the technology and to inspire their curiosity and interest. We will use access time to Scenarios One and Two to reinforce progress and effort made in the driver education program offered in Scenario Three. This way, children are rewarded for diligence and effort, their interest is maintained, and appropriate conceptual motor skills are rehearsed throughout training and while engaging in play activities that follow training. The motorized wheelchairs are operated by manipulating a joystick. Moving the joystick causes the wheelchair to move in the direction that the joystick is pointed and at a speed that is proportional to how far the joystick is pushed. Typically, severely movement-disordered individuals have difficulty in operating a standard proportional joystick. This is due to poorly coordinated skeletal muscle activity in the hand, forearm, upper arm, shoulder girdle, and/or torso.

An effective solution to the problem is to use a simple lowcost piece of adaptive equipment (Mobi Disks ) to train the necessary motor skills. The device enables a user to execute controlled functional movements of the joystick, minimizes motor errors that can compromise function and possibly endanger or frighten the child, and is adjustable so that as motor skills and learned, new ones can be introduced systematically and taught to criterion. Although not required by all children with orthopedic impairment, they are effective training devices for many with severe movement disorders. Mobi Disks are plexiglass plates designed to fit over the top of the joystick and come in five different configurations. Each plate functions to restrict the joystick's range of motion to a greater or lesser degree. In the early stages of training, for example, the plate is very restrictive and permits only a small range of possible movements.

As skill level increases, the plates become less restrictive and permit a far greater range of movement possibilities. Specifically, Plate #1 limits the joystick to a forward movement only. When the stick is moved all the way forward, the chair goes slowly (approximately 50% of normal) and cannot veer right or left. This permits a user to go forward at varying speeds, to keep going as long as s/he wants to or is able to, and to stop when something interesting appears. Plate #2 includes all the forward only options in Plate #1 but includes the option of turning right and left. This greatly enhances the user's ability to explore the environment and to function independently in the community environment. Plate #3 is similar to Plate #2 except that shifting from one direction to another, for example, from forward to making a right-hand turn, does not require the chair to come to a stop between direction changes. Plate #4 is similar to Plate #3 except that the forward function is expanded and allows micro changes to occur while maintaining forward movement. Plate #5 is similar to Plate #4 with the exception that a controlled reverse is available.

Deciding where a particular child gets placed into the training program and determining which mobility training plate should be used during the training process, is arrived at by consulting with administrators and special education teachers who are familiar with students involved in this training effort. There are two overriding concerns that guide the decision process in each case. Specifically, we strive to ensure each student driver is motivated to do his or her best at each stage of training. Therefore, we do not overemphasize massed practice of simple motor skills in a repetitive environment. Rather, we prefer to err on the side of excitement and fun, allowing each student diver to challenge him or herself to the maximum extent possible without becoming terrified. Of course we will also want to build skills systemically in such a way that at the end of training each child is able to do more and go farther, as independently as possible, at the end of training.

By the end of the project we hope to have amassed enough data and experience to begin specifying how these decisions should be made to best use virtual reality as a tool for training functional mobility skills in severely orthopedically impaired children. We gratefully acknowledge the United States Department of Education which has funded this research project for three years, since July 1, 1993 (Grant No. H180E30001).

Go to previous article 
Go to next article 
Return to 1995 VR Table of Contents 
Return to Table of Proceedings 


Reprinted with author(s) permission. Author(s) retain copyright.