Often, when students first acquire their wheelchairs, they receive little or no training on how to operate the chair. In the excitement of getting a new chair, many students forget the initial instructions given by the instructor or the person who delivered the chair. Some of the things described in this chapter may seem basic or obvious, but the instructor should not assume that the student knows all of them. It is beneficial to have the instructor present when the student accepts delivery of the chair, or have a lesson at the supplier’s office. Every chair is different, and both the student and the instructor can learn a lot by consulting with the supplier. Have a checklist or list of questions ready when the supplier demonstrates important features of the chair to the student. As most instructors know, it is important to demonstrate to the student how to operate the different features multiple times to retain the information. Some students may need to have the instructions written down for future reference. If family members or significant others are included in the lessons, they can help the consumer.

Constant Contact Technique

Many students prefer to use the constant contact technique. The cane tip is left on the ground as it sweeps back and forth across the body. Two-point touch is a similar technique where the student arcs the cane from side to side, tapping it once on each side, in an alternating pattern. The techniques are similar and both are beneficial to know. However, two-point touch does not provide as much information about the surface to be covered as constant contact, which also provides information about smaller level changes that might not be distinguishable with two-point touch. The medical conditions that create the need for the chair may also impact the fine motor control needed for effective use of two-point touch.

Cane Length

Wheelchair users should use the longest cane manageable. The longer the cane, the more reaction time the student has. Hence, the longer the cane, the faster the student can drive. Since the wheels of the wheelchair are progressing at the same rate, most students do not need to worry about being in-step with the cane. Students who have the ability to stand and walk may have two canes, one much longer than the other. The shorter cane is measured using standard O&M guidelines. The longer one is only used when driving the wheelchair. The longer the cane, the more it weighs. Some students have to switch back to shorter canes because they quickly become fatigued with the longer canes. The medical conditions that created the need for the wheelchair may also limit hand and arm strength or reduce motor skill. Due to the reduced speed at which they travel, students with manual chairs may need much shorter canes for obstacle detection than students in motorized chairs or scooters. However, the longer cane length may still be beneficial for added reach when searching the environment around the chair.

Cane Types

Most students prefer to use folding canes but should be given the opportunity to practice with a variety of cane types to help determine which type is best for them. The student may decide that the folding type is better in one situation but the rigid cane is better in other situations. Each cane type has its advantages and should be given due consideration.

The thin, rigid fiberglass or carbon fiber canes with metal tips have the advantage of being extremely flexible. When the cane hits a wall or gets stuck in a crack, it will flex. As the cane flexes, the metal tip will often slip out of the crack. The student, therefore, does not absorb all of the impact. These canes are also very light weight, which may benefit students who have arthritis or hand weakness. The grips can be an advantage or a disadvantage, depending on the student and her needs. The grips on National Federation of the Blind (NFB) canes are thinner than the golf grips used on folding canes. This makes it easier to simultaneously grasp the cane and the wheel rails of manual chairs. The disadvantage is that the small size may make them harder to grasp for some students. The handle can be built up by a variety of means, such as foam pipe insulation, tape, or physical therapy putty.

Cane Tips

Many consumers prefer some form of roller tip, such as those sold by AmbuTech. The most commonly used tip is a marshmallow-sized roller tip. It rolls easily and lasts a long time, but it is heavy and gets stuck in some cracks and vegetation along shorelines. Rolling facilitates using constant contact cane technique.

Standard marshmallow-sized roller tip. (S. Crawford)

The roller ball is the size of a billiards ball and will bounce out of most small cracks over which a wheelchair can be driven. The disadvantages are that it is loud and wears out faster than standard roller tips.

Roller ball cane tip. (S. Crawford)

The jumbo roller is very durable, but it does not slide forward as well as other tips. For this reason, it is okay for manual wheelchair users, but does not work well with electric wheelchairs or fast wheelchair travelers. The shape of the tip is such that it will stick in too many small cracks to be effective for outdoor travel. It also does not skip along the surface as well as the other roller tips. Many students travel too fast to allow the cane tip to actually roll instead of sliding along the surface for constant contact technique.

Jumbo roller cane tip. (S. Crawford)

The metal glide tip produces a crisp sound, especially during two-point touch. It slips out of cracks easier and is the only tip that fits on NFB-style rigid canes. It is very sensitive and inexpensive, but it wears out quickly when used with the constant contact technique.

Metal glide cane tip. (S. Crawford)

Hand Position

The centered hand position recommended by most orientation and mobility specialists is not recommended for wheelchair users. The best position for wheelchair users, especially if they are fast travelers, is at the side of the body. When the chair is moving and the cane tip gets stuck in a crack, the stopping distance of the chair is significantly greater than the distance between the student’s hand and stomach. With the hand centered, the cane could either jab the student in the gut or the handle could be driven up toward the face or throat. By keeping the hand to the side, if the cane should get stuck the handle will be driven to the side or over the shoulder.

Watch video CS5a: Cane Techniques: Hand position for wheelchairs.

Cane Grasp

There is no special grasp that is better for wheelchair users. The cane just needs to be held with a grasp that is firm enough to keep from dropping it if the tip gets stuck in a crack. Cane handles held in pencil grasp tend to pop up in the air when the tip gets stuck, causing less force to be absorbed by the student’s elbow and shoulder. Scooter users who choose to keep the cane above the handle bars tend to prefer a pencil grasp. Scooter users that keep the cane low and swing below the handle bars can use either grasp.

Cane Storage

At some point, most students will need to have both hands free for one reason or another. Students have come up with a variety of creative ways to store their canes:

• Slip the tip in the shoe and lean the cane against the shoulder.
• Tuck the cane under the leg with the cane fully extended, folded in half, or fully folded.
• Fold the top part of the cane and tuck it in the back of the shirt or between the back of the seatback. Rest the cane over the shoulder and pinch the tip between the feet.
• With a single foot plate, put the tip on the foot plate and pinch it between the feet. Lean the cane against the torso.
• Attach special clips to hold the cane.
• Tuck the cane into a pocket either on the back or side of the chair or hang it from a handle.

Watch video CS5b: Cane Techniques: Storing the cane for wheelchairs.

Arc Width and Rhythm

It is harder for a wheelchair or scooter user to determine the correct speed to swing a cane than it is for someone walking. Some students are comfortable with swinging the cane one full time before the front of the chair reaches the cleared space. However, be aware that this does not protect the student from side drop-offs and obstacles that do not stretch across the entire path. Side drop-offs are the most dangerous for wheelchair users. Therefore, the cane should swing several inches wider than the chair. To match the coverage of being in step while walking, the cane would have to travel across the path and back before the chair reaches the cleared space. The arc rhythm used should be fast enough to detect obstacles, but not so fast that the student appears to be swinging frantically.

Watch video CS5c: Cane Techniques: Arc width for wheelchairs.

First, the instructor should determine the fastest speed with which the student can comfortably swing the cane. Then, the instructor can decide at what speed the chair is moving too fast for the cane. The instructor should choose a landmark on a wall or the floor and note the position of the cane as it passes that mark. The cane should make one full arc cycle, left and right, before the chair reaches the landmark. If the chair is passing the landmark before the cane makes its full cycle, the student may need to either swing the cane faster or slow down the chair’s speed.

Watch video CS5d: Cane Techniques: Arc speed and rhythm for electric wheelchairs.

The speed settings of a scooter are usually set by a dial. Students who rely on tactile information for maintaining their orientation may not progress beyond half the scooter’s available speed. Beyond half power, the cane may hit an obstacle, but the student may not be able to react fast enough to keep from hitting the obstacle. If the student is not completing the arc cycle before the front of the scooter reaches the landmark, try switching to a longer cane. This will increase the amount of available time to complete the cycle. As the student increases the speed, she may be able to complete an arc cycle by swinging the cane faster, but likely will not be able to feel the surface information or react to obstacles in time. At this speed, the cane is out more for identification purposes or as a probe.

Watch video CS5e: Cane Techniques: Arc speed and rhythm for scooters.

Low vision wheelchair users may decide to trust their vision to assess the path. Different types of lighting, shadows, bright sun, fluctuating vision, visually cluttered environments, and crowded environments can inhibit he student’s ability to accurately detect obstacles and drop-offs. The student may have a safe top speed under ideal visual conditions but another slower top speed at night, in bright sun, in crowds, or in whatever situations give her problems. If the student does not show that judgment, the instructor may have to recommend using the slowest of the top speeds determined. If the student is not willing to slow down, the instructor may have to reconsider recommending independent travel.

Building Reaction Time

There are a couple of methods to teach a student how to react properly to unexpected obstacles. One is to have the instructor walk backward in front of the student while dragging a cane in front of him, just out of reach of the student’s cane. As the student drives forward, the instructor backs away. At some random moment the instructor allows the two canes to hit. That is when the student should stop. However, the instructor should not stop backing away, because the student might use the instructor’s stop as a cue to pay attention to the cane. If the student’s chair rolls past the point where the two canes made contact, she is driving too fast. With practice, the student may improve her reaction time and be able to speed up again, but should continue at a slow pace until there is improvement.

The instructor should vary, within the arc, where the canes make contact. Some students are more successful detecting contact from one direction than the other. For example, the student may be very accurate detecting contact when the cane moves from right to left, but fail (or be slower) to recognize it when her cane moves from left to right. The instructor should also make sure the contacts happen across the width of the arc, not just at the center.

Watch video CS5f: Cane Techniques: Building reaction time.

If the student is watching her cane, or the instructor’s cane, the instructor may want to occlude the student’s vision, either totally or partially. Total occlusion can help direct the student’s attention to her cane. However, if the student has a difficult time maintaining her line of travel, partial occlusion may be more effective. Partial occluders can be made by putting tape or paper over the bottom half of the lenses of a pair of sunshields. By blocking just the bottom half of the visual field, the student should not be able to see the canes, but can still use the upper field of vision to assist with maintaining the line of travel.

Another method to teach a student how to properly react to obstacles is to create an obstacle course. There are three stages of training and some additional advanced work that can be utilized. During the first stage, the student should learn how to detect the obstacle and pull up to it without running into it. The obstacles should be objects that will move easily, such as chairs or small trash cans, so that neither the chair nor the obstacle is damaged during the practice. New cane users may not have a good feel for the distance between them and the cane tip. In turn, new chair users may not have a good feel for the distance the chair will travel with just a tap of the joystick, and scooter drivers often press the throttle-control lever in the wrong direction. As the student improves, obstacles that the student cannot reach out and touch such as books, canes, and ropes should be used. If the student has vision, the obstacles should be of a color that will blend in with the floor. Again, full or partial occlusion can help the student learn to rely on the cane.

Watch video CS5g: Cane Techniques: Obstacle course: Stage one.

The second stage of training involves driving around the obstacle without hitting it. Students often struggle with spatial relationships and bumping things when they turn. Learning when to turn, adjust the speed, or power down is a very important lesson for new students.

Watch video CS5h: Cane Techniques: Obstacle course: Stage two.

The third stage is to navigate successfully a slalom-style course. The student will practice weaving through and around several objects in a line. Many students forget that when the cane contacts something it is a couple feet ahead of them; they want to turn immediately instead of waiting for the wheelchair or scooter to reach the turn.

While the initial obstacle courses can be made with chairs or trash cans, eventually the student should work with lower obstacles that will be harder to see or out of reach without the use of a cane.

Watch video CS5i: Cane Techniques: Obstacle course: Stage three.

If the student appears to be navigating visually without relying on the cane, the instructor may provide lower-field occluders. The occluders allow the student to use lights or walls to maintain her overall orientation, but force her to rely on the cane for information about what is at her feet or wheels. Students who flew through the obstacle course by relying on their vision may be exceedingly slowed with the occluders. In wheelchairs, it is even more important to get information from the cane because the student will lose valuable information by not feeling what is underfoot. Full occlusion forces the student to rely even more on information from the cane. The decision to use either type of occlusion should be discussed with the student and agreed to before initiation.

Watch video CS5j: Cane Techniques: Obstacle course: Stage three with occluders.

The student should also work on identifying landmarks on her chair or body that will alert her as to when to initiate turns around obstacles. The student should have different landmarks for turning in relation to the near side and the far side of the opening.

Watch video CS5k: Cane Techniques: Obstacle course: Identifying landmarks for turns.

Once the student has demonstrated consistency with detecting obstacles, she should work on pulling up to the obstacle and then backing or turning away. While this skill may seem pretty basic, it must be given due attention. Students should practice driving up to chairs or trash cans before attempting to practice with walls or tables.

Navigating tight spaces is one of the most critical skills that the student will learn. It relates to every subsequent area of instruction. Acquiring the skills early in training will reduce the number of accidents the student will have later. If the student struggles with navigating curb ramps or lifts, it is a sign that she needs to review navigating tight spaces, and would probably benefit from practicing in a less stressful environment.

Once outside, the student will need to be able to detect drop-offs, pull up to them, and either back away or turn away from them. Students who appear to have no problem with this while in a safe environment have struggled when in outdoor environments such as facing a drop-off, in a crowd, or with a lot of automobile traffic. Students have driven off curbs because they either overshot the edge or because they moved the throttle-control lever in the wrong direction.

Detecting Drop-Offs With the Cane

For many students, feeling the cane go over a drop-off is more difficult than detecting an obstacle that sticks up from the ground. When a student begins to practice detecting drop-offs, the instructor should be ready to perform emergency stops or to stabilize the chair as it goes over the drop-off. Powered chairs should be set to the slowest speed. The instructor should decide if he wants to be in front, beside, or behind the student. The student and instructor should practice emergency stops on a flat surface before they attempt an actual drop-off. (See Instructor-Controlled Emergency Stops in chapter 7.) If the instructor plans to stand in front of the student while they approach the drop-off, have the student practice pulling up to the instructor on a flat surface before she tries the drop-off.

One technique to try is to have the instructor guide the student to the drop-off while the student uses her cane, stopping when the cane tip goes over the drop-off. Without moving, the student can then practice feeling the cane go over the drop-off several times. The instructor can then guide the student to the curb edge and not stop until the student feels the cane drop off and says “stop.”

Watch video CS5l: Cane Techniques: Detecting drop-offs: Practice with the cane.

If a student is fearful of driving off a curb, it will help if the instructor stands at the edge of the drop-off; this gives the student a place to aim. If the instructor is standing on top of the curb, the student should pull up to either side of him. In an electric wheelchair, the student should pull up so the joystick is on the side closest to the instructor.

Watch video CS5m: Cane Techniques: Detecting drop-offs with electric wheelchairs.

On a scooter, the student should pull up so the instructor is on the student’s left side. From the left, the instructor can grab the handle bars and the throttle-control lever to stop forward momentum and initiate reverse movement if necessary.

Watch video CS5n: Cane Techniques: Detecting drop-offs with scooters.

An alternative is to have the instructor step off the curb and wait at the edge as the student approaches. The instructor should be ready to stop or brace the chair should the student fail to detect the edge. He should be prepared to intervene as the student detects the edge, as she finishes pulling up to the edge, and when she turns the chair around. This is especially important with mid- or front-wheel drive chairs; the back end swings out during turns and could drop off the curb. Leaving the cane hooked over the edge of the curb may help the student keep track of the drop-off.

Watch video CS5o: Cane Techniques: Detecting drop-offs with electric wheelchairs: Instructor off the curb.

When the student is proficient at detecting the drop-off with the instructor standing on or just off the curb, he should back away from the drop-off one or two steps and have the student repeat the process. This prevents the student from using the instructor as a target. One or two steps will allow the instructor to be close enough to step forward and assist if necessary. Eventually, the instructor should back farther away to random distances so the student cannot predict the location of the drop-off by the instructor’s position.

Watch video CS5p: Cane Techniques: Detecting drop-offs: Instructor away from the curb.

A student in an electric wheelchair or scooter should also practice detecting drop-offs that run parallel to the direction of travel with the instructor walking beside the chair. The instructor should be in a position to make an emergency stop if necessary. With an electric chair, the instructor should be on the same side as the joystick; with a scooter, he should be on the left side. The instructor should stay in the same relative position to the chair or scooter throughout the entire process. His hand should be ghosting the joystick or throttle-control lever. Having the instructor move closer to the student or reaching out toward the joystick as the student nears the drop-off will act as a cue.

Watch video CS5q: Cane Techniques: Detecting drop-offs with electric wheelchairs: Ghosting the joystick.

Finally, the student should practice with the instructor behind the chair. The monitoring position of the instructor will depend on his ability to make instructor-controlled stops from the rear of a chair with handles on the back. If the instructor cannot stop the chair from behind, he should monitor from a position where he can stop the chair, and then move to the back after the student demonstrates consistency with stopping. Regardless of the initial monitoring position, the instructor should end the process by monitoring the student from the rear of the chair. In this way, the student will not be able to adopt unconscious cues from the instructor of when to stop.

Determine the Height of Drop-Offs

For some students, it is difficult to visually determine the height of drop-offs. Below is one strategy for using a cane to measure a drop-off.

1. Locate the drop-off with the cane.
2. Pull up to the edge of the drop-off (just like finding the top of the stairs).
3. With the cane tip at the bottom of the drop-off, lean the cane against a solid object, for example, handlebars, joystick box, lap desk, or knee.
4. Place one hand flat on the object with the cane between the thumb and index finger.
5. Place the other hand flat on top of the first hand with the cane between the thumb and index finger.
6. Keeping the first hand on the object, lift the cane with the second hand until the tip clears the top of the drop-off.
7. Rotate the top hand down until the palm is against the cane.
8. If the two hands touch, the drop-off is probably small enough to be navigated. If the hands do not touch, the drop-off is probably too high to navigate.

Watch video CS5r: Cane Techniques: Determine the height of drop-offs.

The height of an obstacle that a chair can safely navigate is determined by the make of the chair, the position of the wheelie bars, and the student’s ability to drive off the drop-off in a straight line. Safety is also affected by the student’s ability to approach the drop-off at a right angle. The two wheels (front or back) should drop or climb together. If the wheels are not in sync, the chair could easily tip over.

Shoreline Strategies

Shoreline strategies include three-point touch, constant contact, touch and drag, and drag and touch techniques. Environmental surfaces, and if the student is searching for something specific, will determine the best technique to use. It is not recommended to shoreline with two-point touch or diagonal technique. Two-point touch does not tell the student where the transition between surfaces is located and may lead to the student driving off a drop-off. Diagonal technique is not recommended because it does not clear the path in front of the student. If the student’s vision requires using a long cane, it should be moving to clear her path. If the wheels are moving, the cane should be moving.

The terms two-point touch, three-point touch, constant contact, and touch and drag are commonly used in the field of Orientation and Mobility. If the reader is not familiar with these terms, consult a Certified Orientation and Mobility Specialist (COMS). The techniques described here may be familiar by a different name.

Two-point touch: The cane taps the ground in two places, at the far sides of the arc. The tip is lifted off the ground as little as possible as it crosses the path. The taps should be a couple inches wider than the width of the wheelchair. It is more difficult than it sounds.

Watch video CS5s: Cane Techniques: Two-point touch.

Three-point touch: The cane tip taps the ground in three places. The first tap is in front of the foot farthest from the shoreline; the second tap is in front of the foot closest to the shoreline; and the third tap is on the wall or in the shoreline. The cane then returns to tap in front of the foot farthest from the shoreline as the first tap of the next cycle. Three-point touch is used when the student is trying to locate an intersecting walkway, bus stop, pedestrian locator button, or something else off to the side of the path.

Watch video CS5t: Cane Techniques: Three-point touch.

Constant contact: The cane tip is left on the ground as the student swings it left and right. The cane tip hits the shoreline each time it sweeps to the side closest to the shoreline. This technique is what most wheelchair users prefer for straight line travel, when they are not trying to locate anything in the shoreline. Most students will detect more cracks and drop-offs with constant contact, but the tip does get stuck frequently.

Watch video CS5u: Cane Techniques: Constant contact technique.

Touch and drag: The cane tip touches the ground on the side farthest from the shoreline, then is swept or dragged on the ground, across the body, until it touches the shoreline. The cane tip is then lifted and swung through the air to touch the ground again on the side farthest from the shoreline. Touch and drag is preferred when the student wants to follow an edge to get to the end, not locate something in the shoreline.

Watch video CS5v: Cane Techniques: Touch and drag technique.

Drag and touch: A modification of touch and drag where the cane touches the ground in front of the foot farthest from the shoreline, and is dragged across the body until it touches the shoreline. The tip is then lifted and swung to the side, into the shoreline. Finally, the tip is lifted and swung back across the body to touch the ground in front of the foot farthest from the shoreline. When driving in the street, drag and touch is excellent for finding intersecting walkways, signs, and so forth.

Watch video CS5w: Cane Techniques: Drag and touch technique.

The student may wish to switch the cane to the hand closest to the shoreline being explored. Items that are located immediately next to the sidewalk can usually be found with standard shorelining techniques. Items that are set back into the grass will be missed unless the student exaggerates the swing into the shoreline. If the student is searching for bus stop poles, pedestrian locator buttons, or other landmarks that may be set well back into the shoreline, switching the cane to the shoreline hand will allow her to reach as far into the shoreline as possible. When electric wheelchair users have the shoreline on the same side of the chair as the joystick, they may have to modify their technique. In an electric wheelchair, the student may have to drive forward, stop the chair, switch the cane to the hand on the joystick side, sweep the cane into the shoreline, switch the cane back to the hand opposite the shoreline, and then drive forward again. This is a very slow process, but is sometimes necessary. Travelers with residual vision, may try to spot objects in the shoreline visually, and then use the cane to check out the items.

Watch video CS5x: Cane Techniques: Shoreline on the same side as joystick of an electric wheelchair.

Constant contact and touch and drag are most effective for shorelining curbs, following walls, or anytime when the main purpose is using the shoreline to maintain a line of travel. Neither technique is recommended for locating intersecting walkways or curb ramps because the cane will sometimes catch in grass growing in a crack or a seam between the sidewalk and the walkway; or if the transition to the walkway or curb ramp is not smooth, the cane can catch in the crack and provide incorrect information about the shoreline. If the student is modifying her technique to roll the cane all the way into the grass, it may actually pass far enough into the grass growing in the crack to detect the concrete on the other side. Some students do this naturally, but others will need prompts to do so when needed.

Watch video CS5y: Cane Techniques: Constant contact with grass in sidewalk seam.

Another technique is to use drag and touch, where the cane tip rolls across the sidewalk to the hit the edge, then is lifted to reach deeper into the shoreline. Drag and touch is most effective for locating objects that are set back into the shoreline, locating intersecting walkways or sidewalks, or anytime when the main purpose is to locate something to the side of the wheelchair or scooter.

Watch video CS5z: Cane Techniques: Drag and touch with grass in sidewalk seam.

Drag and touch or three-point touch are recommended anytime the student is looking for something in the shoreline or to the side. If the student is just trying to get to the end of a road, sidewalk, or hallway, she will not need to make the extra contact farther into the shoreline.

When the ground surface is too rough to roll the cane, the student may need to change techniques. Three-point touch does not provide as much information about the ground to be covered as the other techniques, but is sometimes necessary when the student is traversing on grass or a badly broken sidewalk. The first two taps of the cane should touch as close to where the wheels will pass as possible. The third tap is to the side of the chair. If the student is uncertain about the surface, she may incorporate additional taps to check the surface. Some students will tap the cane seven or eight times per swing. The student may also choose to reach out and draw the cane back toward the chair to try to locate the smoothest spaces to drive over. Whatever technique is used, the student should navigate these areas at a slower than normal speed, but with enough speed to give the chair or scooter sufficient power to make it through the rough area.

Watch video CS5aa: Cane Techniques: Three-point touch on uneven ground.

Electronic Travel Aides (ETAs)

Because of the changing availability of electronic travel aides from year to year, it is difficult to make definitive statements about using ETAs with wheelchairs. Therefore, instead of discussing specific devices by brand, the advantages and disadvantages of different types of ETAs will be discussed.

Head-borne ETAs have the advantage of leaving the hands free to operate the cane and the chair. Many of the head-borne devices give dual signals, allowing for stereo output. A student with good hearing in both ears can point directly to the object the device is indicating. The disadvantage is that to direct the ETA to the side, the student must turn her head to the side, which can result in the chair veering in the direction the head is turned. The student may learn not to veer with her head turned, but most do not. Some students find head-borne devices to be too conspicuous and will not use them for that reason.

The advantage of a handheld device is it can be pointed in any direction, including to the rear, and can easily scan the environment for a variety of objects or obstacles. The disadvantage of holding an ETA is that it restricts one hand that may be required for cane use.

Some ETAs are mounted on canes, allowing the student to use the ETA and the cane at the same time. The student can pivot the cane easily to search beside the chair instead of in front.

Other ETAs hang around the neck. These have been effectively used by students in manual chairs in indoor environments for detecting the end of hallways and other pedestrians. If the student needs to detect objects to the side of the chair, she can pick it up and turn it or adjust it to hang to the side instead of to the front.

Chair mounted ETAs have also been developed. Chairs with fixed mounted ETAs have three mounts: one each facing front, right, and left. Chairs with adjustable mounts allow the student to pivot the ETA in any direction. Smaller handheld devices can be temporarily attached to the chair with hook and loop material.

Note that in outdoor or unfamiliar areas, ETAs are not reliable for drop-off detection. The level of perception of the device is too low to discern small drop-offs that could cause the chair to upend. ETAs also struggle with distinguishing unstable surfaces that may give false feedback. For example, a sidewalk with a 6-inch drop-off may have grass growing beside it that is 5 inches tall. The ETA will identify the grass, but not the entire drop-off and give the student false feedback of only 1 inch. While each chair is different, a drop of roughly 2 inches, if hit at an angle, is enough to cause the chair to overturn.

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