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Randy Marsden, P.Eng.
President, Madentec Limited
Access to the computer in today’s modern world is no longer a luxury – it’s quickly becoming a necessity with more and more reliance on email, web access, and information processing. This is even more the case for those unable to use their hands. For these individuals, the computer represents a tool for achieving an education, vocation, and independence. It is therefore essential that today’s computers be accessible to everyone – even if they can’t use their hands.
Madentec has put together a series of products that, when used together, allow complete computer access with nothing more than head movement. Called the 2000 series, these products replace the functions of the mouse, mouse button, and keyboard.
Mouse Replacement (Tracker 2000)
The first barrier to computer access for someone unable to use their hands is the mouse. The Tracker 2000 overcomes this barrier by tracking the movement of a user’s head, and converting it to mouse signals. The user wears a small reflective sticker on their forehead or glasses. Tracker is positioned on the computer’s monitor or screen and emits infrared signals to the reflective dot which in turn reflects the signals back to Tracker. In this way, the movement of the user’s head is accurately measured and converted to smooth mouse movement.
Tracker can be mounted horizontally on a desktop computer, or vertically on a laptop computer. The built-in camera ball swivels through 120 degrees to ensure accurate alignment with the user’s head.
Figure 1: Vertical and Horizontal Mounting
Sunlight Interference Solved
A serious problem with previous infrared head pointing systems was interference from sunlight and other infrared light sources (such as incandescent light bulbs, fluorescent lights, and windows). Special image processing filters in Tracker 2000 have solved this problem, allowing it to be used in direct sunlight, including outside.
An experiment was conducted comparing the performance of Tracker 2000 and other infrared head pointers (including Tracker’s predecessor, Tracker Classic) in normal and sunlight conditions. The results are shown next:
Figure 2: Sunlight Interference Experiment Results
It is clear from this study (conducted by Ron Willis, Ph.D, Professional Engineer) that Tracker 2000 passes the sunlight test with impressive results.
Many types of disability leave the user unable to provide precise head movement. Examples of these are cerebral palsy and muscular dystrophy. Tracker 2000 offers a unique "joystick" mode which allows these types of individuals to still access the computer by direct pointing.
In joystick mode, Tracker watches the movement of the user’s head, and interprets it the same way a joystick interprets movement: if the user leans and holds their head to left, the cursor smoothly glides left until their head returns to center, and so on. Using this scheme, the user can guide the cursor in 8 directions: left, right, up, down, and 45 degrees in between each of those.
LEDs on the front of Tracker help indicate to the user which way the conceptual joystick lever is pulled (see the photo). Many people who otherwise would have had to access the computer using scanning have successfully become direct pointers using Tracker 2000’s joystick mode.
Figure 3: Tracker in joystick mode (moving left)
Using Tracker with AAC Devices
Tracker 2000 is compatible with most Alternative and Augmentative Communication (AAC) devices, both in mouse and joystick modes. This opens a whole new exciting method of access to AAC that was previously not possible, and provides an important alternative to scanning for many users. Tracker’s AAC compatibility includes the Vanguard, Dynavox, Dynamyte, and all computer-based AAC systems.
Figure 4: Tracker mounted on a Dynavox 3100
Set the selection technique on the AAC device to "Head pointing", and plug Tracker into the port which normally accepts mouse input ("Multiswitch" port on the Vanguard, and the Serial port on the Dynavox). Most devices allow you to adjust horizontal and vertical sensitivity independently, as well as whether you want to use a switch or dwell to make your selection.
Tracker can be mounted on most of the AAC devices using the special longer mounting hooks, along with Velcro for added stability. Or, if you prefer, you can use a custom mounting plate attached to Tracker’s ¼ inch tri-pod mount.
Tracker must be powered independently of the AAC device. This can be accomplished by using Madentec’s wheelchair battery adapter (if it is being used on a powered wheelchair), or an optional external battery pack.
Here is what one AAC user had to say about Tracker 2000:
"Tracker 2000 is wonderful. I use it to operate a DynaMyte and … to give speeches (via the DynaMyte voice synthesizer) and find that it is not at all distracted by spotlights or backlighting. Most amazing to me, I use the Tracker 2000 to operate a digital camera, and it works perfectly, even outdoors with the sun directly behind me. Thanks for the great improvement."
Joe Martin, Charlotte NC
(ALS, unable to use hands, legs or voice)
Microsoft Corporation has developed unique software titled "IntelliPoint" which ships with every wheelmouse they manufacture. This software adds numerous advanced features to the computer’s mouse control panel. Some of the more notable of these features being: a mouse odometer, snap the cursor to default buttons, slow down over close boxes, and many more. All of these features are relevant and extremely useful to people using a head pointer.
Perhaps the most significant feature of IntelliPoint, is the scrolling cursor. Clicking the button in the wheel of the wheelmouse (or by holding the right button down for 2 seconds on Tracker 2000), causes a special icon to appear on the screen where the cursor was.
Figure 5: Intellipoint Scrolling Icon
Once the icon is placed on the screen, the cursor can be moved above or below it to scroll the active window up or down. The further the cursor moves from the icon, the faster the resulting scroll action. (The same can also be accomplished for left, right, or diagonals in windows with horizontal scroll bars).
This feature can be extremely useful to people using headpointers to access the internet. Using Intellipoint, they can scroll a large page by simply moving their head up and down (instead of having to continuously click on the scroll buttons).
Any electronic device with CPU clock speeds of more than 16kHz must have the device tested to comply with FCC Part 15 for electromagnetic interference (EMI) – that includes nearly every device out there that is using a microprocessor.
FCC Part 15 certification ensures the device is not emitting enough EMI to cause serious harm to humans and/or other electronic equipment. If the device is intended to be used in a home or hospital, it must comply with the more stringent section of FCC Part 15: Class B.
Tracker is fully certified as having complied with FCC Part 15, Class B (most competing head pointers are not). That means it is safe for use in homes and is legal to sell commercially. (Parties involved with devices that are sold commercially, but which have not met proper FCC certification standards, are subject to prosecution – including both the buyer and the seller).
Mouse Button Replacement (WISP and Magic Cursor)
Tracker 2000 takes care of replacing mouse movements for many users, but how do you replace the mouse button? There are at least five answers to that question: wired ability switches, wireless ability switches, a head mounted sip/puff switch, head mounted fiber-optic switches, and automatic dwell selection. Each of these are listed below.
There is a connector on the rear plate of Tracker 2000 which will accept input from one or two ability switches (for left and right mouse buttons). This connector is a 3.5mm stereo jack. A stereo splitter is supplied with Tracker, allowing two separate "mono" switches to be plugged in.
Wireless Ability Switches
The problem with plugging an ability switch directly into the rear of Tracker, is it tethers the user to the computer (assuming the switch is mounted on the wheelchair of the user). We have addressed this problem by developing "WISP 2000" – a wireless, integrated, switch platform. WISP is made up of a transmitter and receiver pair that communicate via radio frequency (RF) signals.
Switches are plugged into the transmitter which is mounted out of sight anywhere on the wheelchair. A unique digital signal is sent from the transmitter to the receiver when a switch is pressed. The receiver then outputs the switch closure through a standard 3.5mm female jack.
Figure 6: WISP transmitter/receiver pair
The transmitter and receiver are "mated" using one of 16 combinations available on DIP switches located on both devices. (This works exactly the same as a garage door opener encoder). This means more than one WISP can be used in the same room or facility without interference one with another.
For most people using Tracker, it is difficult to hold their head still and actuate an external ability switch at the same time. Inevitably, moving to hit the switch will cause their head to move as well. To solve this problem, we introduced a Sip/Puff switch to the WISP platform. A headset wraps behind the head and over the ears to provide a sturdy mount for the sip/puff tube. The tube is very thin and discrete. Surgical tubing connects the sip/puff straw directly into the WISP transmitter.
Using the Sip/Puff switch, users can left and right mouse button click easily without causing un-wanted head movement. Using this scheme, the switch (sip/puff tube) follows the movement of the head automatically. The pressure required to actuate a switch closure is minimal: pressure created by simple cheek movement is sufficient.
Figure 7: WISP sip/puff straw
Figure 8: Optical switch and Laser option
A cleaning kit is included with every WISP ensure the puff tube remains clean.
Optical Switch and Laser Pointer (WISP)
For some, putting the sip/puff tube in their mouth in undesirable for various aesthetic reasons. As an alternative, we have developed a special face switch based on fiber optic technology. These switches are actuated whenever the beam of light emitting from the end of the fiber is blocked.
The switches mount over the ear and come down alongside the cheek. The positioning of the switch is fully adjustable. Users click by simply pulling back the corner of their mouth or squinting to break the light beam.
An additional option is a laser pointer which is also mounted over the ear. This can be used to point at things for people who can’t use their hands to point. Identifying objects, directing care attendants, and getting someone’s attention are common uses of the laser pointer. The laser can be turned on and off directly by the user, but also turns itself off after 20 seconds. Care must be taken not to shine the laser directly in someone else’s eyes.
Dwell Selection (Magic Cursor)
The final solution to clicking is dwell selection software called Magic Cursor 2000. The user can simply dwell over a selection and Magic Cursor will automatically click on it for them. A palette floats above all other windows and provides the user a choice of click, double-click, and drag for left, right, and middle mouse buttons. A unique "bar" appears beside the cursor that fills from the bottom to the top to provide dwelling feedback to the user: when the bar is completely filled, the action is performed.
Figure 9: Magic Cursor Palette (click, double-click, drag, prefs, left/right/scroll, pause)
An advanced setting allows the user to "gesture" to produce mouse button actions. For example, to click on a folder, the user would dwell over the folder and then gesture to the left: a click would result. To double click, the user would gesture to the right after dwelling; down would result in a drag, and so on. Using gestures, clicking can be performed quicker than using the palette: almost as fast as using an external switch to click. See also the separate white paper for Magic Cursor.
Keyboard Replacement (ScreenDoors 2000)
The third and final input device that must be replaced is the keyboard. With the advent of voice recognition speech-to-text engines, word processing by voice is becoming more and more of a reality. However, there are still many other functions that a keyboard performs, including creating text quietly without speaking out loud. Therefore, a person with a disability still requires a functional replacement for the physical keyboard.
Point and Click keyboard
ScreenDoors 2000 is a perfect companion to Tracker and WISP. It completely replaces the functions of the regular keyboard. It contains all the same keys as the physical keyboard, including the Windows and Menu keys.
Figure 10: ScreenDoors on-screen keyboard
Numerous options are available to customize the keyboard to a desired look and feel. It is completely resizable, the colors can easily be changed, there are numerous keyboard layouts, and dozens of other features make it very flexible.
The keyboard can be activated by any of the following methods: point and click, dwell (built-in), and scanning. It floats above any other window (or not – this feature is user selectable), and can be quickly docked to the top or bottom of the screen. Microsoft licensed a simpler version of ScreenDoors with a limited function set for inclusion in Windows 2000.
One of the most powerful features of ScreenDoors is its ability to automatically adapt to any language selected in Windows. A language can be selected from the System Tooltray (located at the bottom right of the screen), and ScreenDoors will automatically change to that language (as seen in the French keyboard below).
Figure 11: French Keyboard layout
To help speed text entry, a powerful word prediction window is provided. The software makes intelligent guesses concerning the words that are being typed. It will offer words in the order of the probability, based on past usage. The word predictor will also automatically provide a list of "next words" that are most likely to follow the one just entered.
Advanced features of the word predictor include: abbreviation expansion, importation of text to train the word predictor, automatic learning, and full dictionary editing tools. Using the word predictor with the on-screen keyboard can significantly speed text entry.
The 2000 series of products (Tracker, WISP, Magic Cursor, and ScreenDoors) completely replace the functions of a mouse, mouse button, and keyboard. Using these products, the user need only have some degree of control over head movement to completely enjoy the computer experience. These solutions can open new doors for people with disabilities, providing them with a powerful tool for accessing the internet, pursuing an education, obtaining a vocation, communicating, or simply using the computer to enhance their independence.
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