Feedback design implementation

As the date draws closer for our first practical demonstration of the WiiCane system, I am building computer application that processes the raw data and events recognized by Zach's driver.  As of now, I have created a single screen that I think includes data entry fields, indicators and graphics we will need for this first iteration. It should be noted that this design is preliminary and will undergo changes as we proceed.

In the image above, I divided the screen into four zones:

• Raw Data, where we see numeric values returned from both WiiMote units (cane mounted and body mounted).  
• Position, where we see a plan view of the WiiCane course. An avatar representing the user moves along the course to indicate progress, and a stick moves back and forth to show the cane's position at each tap event. 
• Indicators and Settings, which includes large color fields meant to be visible from the far end of the course. The indicators change color in synchronization with tap and veering events as perceived by the WiiCane system. Text boxes in this area allow the administrator to set threshold values for these items.
• Feedback. This section includes boxes where the administrator can create or edit text for each utterance that the system will speak into the user's wireless headphones as he walks along the course. 

In Gene's post of October 12, he discusses the variety of feedbacks that will be needed. I believe that I have captured his recommendations here, but this may require some discussion from the group, since the way that feedback is delivered is the key factor in affecting student learning and improvement. Keep in mind, we are only dealing with one case here, that is where feedback is being delivered in speech, not sound effects or vibration, and we are only, for now, looking at veering and coverage.

The six feedbacks for now are:

• Correct veering right
• Correct veering left
• Increase coverage right
• Increase coverage left
• Decrease coverage right
• Decrease coverage left

One question that still needs to be addressed is how often feedback should be issued for a particular condition. Gene mentioned three times for a particular behavior before issuing feedback. This needs to be considered carefully. Does the counter reset if a different error is observed?  I think that the only way to really know how to do this is by trying it out, so everyone should be prepared for the system to require a lot of revision before it becomes useful.

Testing Protocol as of 25 October 2009

Version 2, 10/21/09

WiiCane: An Accelerometer-based Tool for Mobility Training

Touch Graphics, Inc.

330 West 38^th Street Suite 900

New York, New York 10018

Phone (212) 375-6341, Fax (646) 452-4211

Testing Protocol

Creation of the Device

The WiiCane project proposes to adapt the Wii gaming technology to develop a feedback device for long-cane mobility training for blind and deaf-blind children and adults.  The Nintendo Wii gaming console includes a small, lightweight, inexpensive WiiRemote component with accelerometer-based motion tracking.  The current project proposes to use this device attached to the shaft of a cane during mobility training.  The device will provide auditory or vibratory feedback to the cane user for immediate correction of movement and will also provide computerized tracking information for instructors and researchers.  The project will focus on the device’s ability to monitor two specific cane-use behaviors:  maintenance of the user’s direction within a straight line path; and cane arc width adequate to insure footfall preview (for hazard protection).  The objective is to create a device that is easy and fun for the user and that provides corrective feedback to improve cane mobility instruction and learning.  A diagram of the device is attached to Form 4.13B (Device) showing how the WiiRemote component is mounted below the handle of a cane, enabling it to pivot so that the camera can be directed either in front of the user or under the cane to monitor motion and direction. 

Verification Study

The first stage of product testing was a verification experiment.  This experiment has taken place at Western Michigan University at Kalamazoo.  This location was chosen in order to use the consultation services of Dr. Robert Wall Emerson of the University’s world-renowned Department of Blindness and Low Vision Studies.  The verification study has helped the development team confirm the accuracy of their proposed motion capture apparatus by comparing the data it collects with the known accuracy of the optical tools developed by Dr. Emerson.  The study also provided recommendations for improving the device’s measurement algorithms.  Since Dr. Emerson’s optical tracking equipment is too bulky and delicate to ship, it was preferable to conduct the verification study at his home site.  The subjects were ten sighted college students recruited through advertisements and classroom announcements.  

Since WMU maintains its own IRB, this experiment was submitted separately for review at their local IRB. Since the subjects were all over 18 years old, and since they wore blindfolds to simulate blindness, they were not considered a protected population, and we expected the IRB submission to qualify for expedited or exempt status.   This experiment, and its participants, are completely separate from the experiment in the current application to IRC; it is acknowledged here because of its common funding source and because it will result in information for improvement of the device to be used in the current study.

Recruitment and Consent Process

Following the verification study, the Testing Coordinator will contact staff at each of four test sites to identify potential participants for usability testing of the device, scheduled for November 2009. Test Sites and age ranges for recruitment are as follows; 8 participants per site, for a total of 32 participants, are anticipated.

• Jewish Guild for the Blind, participant ages 2-4.
• New York Institute for Special Education, participant ages 5-12.
• Overbrook School for the Blind, participant ages 13-22.
• Helen Keller National Center, participant ages 17-adult.

Testing will start with children aged six and older.  We will add younger children to the testing, at the sites indicated, only once success with older ones has been shown. 

Participants must be visually impaired, and must use mobility canes for independent travel. Participants at the Helen Keller National Center will be deaf-blind.  Participants at all sites should have no additional disabilities, including motor, cognitive or behavioral problems.  An appropriate staff person at each institution will be identified as a liaison to participants and will be responsible for collection and transmission of data as needed.  Once the liaison at each institution has identified qualified candidates, the liaison will contact adults, or children’s parent or guardian, to discuss the testing protocols, requirements for participating, payment for participation, and procedures put in place for the protection of human subjects in research. 

The liaison will contact potential participants or their parents by a letter either given to the adult participant or sent home with the child as is often done with parental permission slips.  If this is not feasible in an individual case, the letter script may be communicated by telephone or by e-mail.  A copy of the letter/telephone/e-mail script is provided as a separate document.  Students asked to participate will be given a consent form to give to their parent to sign and to bring back to the liaison.  Consent forms are provided as separate documents.  Students and parents will have time to consider the study and to ask questions before they have to make a decision.  As noted in the consent form, students or parents with questions about the study may contact the testing coordinator or the project evaluator.  Their names, e-mail addresses and home telephone numbers are given, and they will receive their messages every day.  The consent form also provides the e-mail address and phone number of IRC in case students or parents have questions about their rights as research subjects.  Willing participants or their parent will also receive an electronic version of the Pre-Participation Questionnaire.  This document assesses the participant’s degree of visual impairment, educational background and cane experience and is included in the IRC submission.  It will be administered and collected by the liaison.

Usability Testing

Usability testing will take place at the named sites over a four-week period, one week per site, beginning with participants aged six or older.  Younger children will be tested only after success with older children has been established.  The Co-PI for Pedagogy, who is a qualified orientation and mobility specialist on the project staff, and a testing assistant will conduct one to two sessions lasting around  one hour with each participant.  This time includes equipment setup, interview, preparation, trials with each participant, and a brief post-trial interview.  A staff member from the test site host organization will be present during all test sessions but will not administer the testing.   

Participants or their parent will be told both in the consent form and at the time of testing that we want them to try out the device to see if it is useful and to solicit their reactions for the purpose of improving the product, not to evaluate them personally.  In each session, the participant will first try out the WiiCane device, making sure that he or she understands the meanings of various feedbacks (either audible or vibratory, or, in the case of the deaf-blind participants, only vibratory).  Next, the participant will be asked to walk along a 30-foot-long course, using the WiiCane as a mobility aid.  The computer will monitor their movements and will generate a complete record of their performance in each session.  Benign auditory or vibratory signal feedback will be sent from the computer to the participant through the device or through wireless headphones, and the system will log for future analysis the participant’s ability to use the feedback to correct behaviors that fall outside pre-set allowable ranges. In order to insure uniformity of vision across subjects, partially-sighted participants will be asked to wear a customized occluded goggle so that they cannot use vision to alter their cane use.  This will be explained in advance in the consent form.  Participants who consent but then express anxiety at wearing the goggle will be allowed to discontinue their participation with full payment.  At the end of testing, participants will be asked a series of questions designed to elicit their responses to the system.

Payment to participants ($150 plus travel reimbursement) will be made in cash on completing the session, and they will sign a receipt.  It will be given directly to the adult participant or to an accompanying parent.  Payment will be made to all participants who attend the session, even if they choose not to complete the study.  Payment will not be made to students who do not attend the session.

Data analysis will focus on the usability and effectiveness of the remote feedback to improve participants’ cane use for the two behavioral criteria (maintenance of a straight line path and use of a proper-sized cane arc).  All records will be maintained by Dr. Annette Gourgey, project evaluator, for a period of five years.  All participants will be identified by an ID number and Dr. Gourgey will be the only person in possession of the master list of names and numbers.  Only Mr. Landau and Drs. Bourquin and Gourgey will have access to the records.

The long-term goal is consistent with Touch Graphics, Inc.’s practice of conducting high quality research and converting the findings to practical and needed assistive and accessible educational materials.  Thus, the Company will seek to make necessary changes to the WiiCane system as suggested by the research outcomes, to be followed by a product roll-out within one year of the end of the project.  We will design and manufacture a custom cane that includes a pivoting fixture for mounting the WiiRemote device.  The software will run on any PC that has Bluetooth capability (normally included with most recent laptops, and easy to add to desktop models and older laptops with an inexpensive expansion card).  With the addition of Owner’s Manuals and packaging and promotional materials, we hope to start selling up to 100 systems per year, at a total cost to an organizational customer of $1,200, including setup and training.  Realistically, students could begin training on the WiiCane as early as late 2010. 

IRB language

I agree with Annette that we should avoid the word "injury" in the informed consent documents.  I would have preferred to leave this out altogether, since we have never included a statement like this in the past. But in thinking through potential scenarios, however, I imagine that someone could fall down and get injured while using the system, especially since we are occluding subjects' hearing and vision.  Apart from IRB considerations, what are the real risks here? What if someone does crash into a wall or trip over something and fall?  Gene, given your experience with this kind of instruction, and based on what you imagine will happen in the testing, is there a real risk of people getting injured, and is this risk greater than what would be encountered in standard O&M training? What special training or precautions should we be taking? While I don't want to raise any red flags that could interfere with our IRB certification, I also don't want to do anything that could be construed later as reflecting a failure to adequately protect our subjects or users of any commercial products that come out of this research.

One precaution that I think we should consider is to allow the test administrator to speak directly to the subject via the wireless headphones. While this will not work for d/b subjects, it could be a good way to intervene in the case that a subject is veering widely and is heading for a crash.  The administrator could wear a headset with a microphone, and then we would mix his voice prompts with the system-produced feedback in the computer. Ultimately, I am hoping that the commercial WiiCane project will not include any occlusion of remaining vision or hearing.  I understand why it is needed from the experimental design perspective, but I am not sure that this is a requirement from the pedagogical perspective. While we want to add to the literature by developing experiments that are comparable to those carried out by other researchers (e.g., Guth), our ultimate goal is to produce a practical training apparatus for teaching cane travel techniques, so we have to satisfy both of those cases.

I would like to go forward and resubmit the two informed consent documents in their latest form. Let's see what the IRB does; if they are comfortable with this, then we can proceed. But I want to go on record as saying that we will need to be highly vigilant at the test sites. If we are occluding hearing and remaining vision in children and then asking them to walk around, we have to be absolutely sure that we are not placing them in a dangerous situation, regardless of who actually has to pay in the event that one of them gets injured. Our goal is to test a practical teaching system, and we should be less concerned about the absolute purity of our experimental design. I think that this is a very important issue, and while we are addressing it very late in the day, I believe that this is a subject that requires further consideration and discussion before any testing can take place.

I would be grateful for any and all comments on this subject.

optimum criteria for subject selection for testing

Steve,

I understand you will be visiting some of the sites and meeting with key site personnel.

I suggest you share the criteria below with the administrators and O&M folks so we will have the best chance of success. I hope others respond to this with other ideas or corrections.

Criteria:
- the subject should have the capacity to tap a cane back and forth as they move forward
- the subject should understands the concepts of left and right; or, the subject can move left or right depending on which ear he/she hears a sound.

This is a short list but I think if you present this to the sites they will know which children are appropriate and which are not. We might also ask that teachers work on these skills with the children in anticipation of the testing.I am guessing we can assume we will not get 8 kids at each site that can do these things, but the more the better.

I suspect others might be able to add qualitatively and quantitatively to this post.

posts from recent emails

Steve requested I place some of our emails here on the blog. Here they are.

- - -

Sorry I've been absent from this discussion all day as I have been out of town. I have thought more about this and I don't want to underestimate the abilities of the young children in this project. I don't know these students so maybe they are not as involved as the students I am accustomed to working with over the years. And are we talking 3, 4, or 5 year olds? There is a BIG difference in even 6 months in regards to cognitive and conceptual development.

I can agree with trying using the feedback in the left ear to see if the child will move more toward this side etc. Young children are typically adept at moving toward sound sources. So this might work for a child who doesn't really have a deep understanding of laterality. It might result in more of a move toward the direction of the sound in my ear type behavior, instead of a conceptual understanding of straight line travel. But if using the Wii feedback system illicits the desired behavior, this is a good thing.

In response to Gene's comment - Here's my big problem with this and maybe Bonnie or you could explain so my simple mind can get it . . . what's the difference between learning the word RIGHT and what it means, from learning a particular sound and what it means. They seem like very similar cognitive tasks. Both use the auditory pathways, both require the child to understand the difference between lef/right, and both require the child to pair a label (sound or word) with the proper concept and react to it. So what's the difference and why would one be better/easier than the other? In my gut I would suspect the word would be easier. But what the heck do I know!?

I understand this and am I don't disagree. What I am questioning is the conceptual understanding of left/right in children 4 and under.

I need to seek out literature on children learning the concepts of laterality. It has been my experience that blind children, even as young as age 4, can respond correctly to "touch your right ear", "touch your left foot", etc but they don't truly understand more advanced concepts such as "move your cane tip to the right", "turn your body left", until months or a year after they understand they have two of some body parts, and a left and a right side. You can see this development when you administer the Cratty & Sams Body Image for Blind Children checklist. Maybe we should ask the O&M specialist to do this with each child before data collection. It only takes about 20 minutes per child. This starts with body parts, then body planes, laterality, manipulating objects in relation to body to demonstrate spatial understanding of laterality, movements to left/rigth and directionality (left/right on others). I'll dig this instrument up and attach a file tomorrow.

Finally, what percentage of the subjects are children age 5 and under? If what we develop works for school age children and adults, then the project has accomplished some of it goals, right?

Bonnie

- - -

Hi everyone! I just saw a video by Dr. Bil Hawkins who used a WHISTLE to give feedback for veering while crossing the street. Now, I would never, ever suggest that we distract students while crossing streets by sending them coded messages about their veering (perfect scenario for the need for isolated veering training OFF THE STREET with the wiicane!), but this auditory feedback might be something that could work with Wiicane. We can ask Bil for details, but from the video it seemed that if the student veered a little to the left, he got a long, slow descending whistle. If he veered sharply to the right, he got a quick rising whistle. Bonnie, do you think kids who can't remember L-R could learn that if the "left veer" (descending) whistle was played in the left ear it meant they had veered to the left, and if the "right veer" (rising) whistle was played in the right ear, they had veeered to the right? P.S. I tried to log into the blog to publish my comments, it said it was emailing me my new password but I've gotten no message. So I'll continue to email comments, hope that's okay. -- Dona

project status and ongoing discussions

First, I need to apologize for not participating in the ongoing discussions that are occurring on email regarding which feedback types are appropriate for young children and also which style of cane use our system will train students for.  As I mentioned, last week  for me was consumed with preparing for and then attending a great conference at the Metropolitan Museum.  Now that's over and my full attention is shifting onto WiiCane for the next two weeks as we get ready to do our first field tests.

I need to reiterate that our group discussions must take place on this blog, so that we end up with a coherent record of our conversations, and so that all project participants can easily keep abreast of our developments and make contributions as needed. I understand that there were some oversights in distributing invitiations to  blog participants, and I also know that it can seem easier or more satisfying to just fire off an email to one or two people, but it is important to the overall project that we use the blog. I expect traffic to pick up significantly now, so it's really a very good idea to subscribe to the email digest that will come to you on every day when there is some blog activity. If you have not signed up for that yet, please do so by filling in your email address in the text box in the upper right corner of the blog and then clicking "subscribe".  If you have not received an invitation to participate in the blog, please let me or Gene know, and we will take care of it.

Regarding the question of how best to provide corrective messages to young children undergoing training with WiiCane: I think that this is a question that will be clarified quickly when we start running kids.  My guess is that directional audio that plays a tone in the ear on the side toward which the correction should be made will be more effective than saying "move right" or "move left".  But, it's easy to create a feedback system that allows for either option to be set, so we should have no difficulty in determining which works best, or, we provide both options and allow the test administrator to decide.

On the question of two-point tap vs. constant contact: my understanding is that most users these days are trained in constant contact, and so we need to ensure that our system reflects this preference. We should not develop a system that is only capable of providing instruction in an obsolete or unpopular method for cane use.  But, the proposal was written specifically to address two-point touch, and so we need to do that first. Once we get that working, we can augment the system so that it can also be used for training constant contact also. From a technical perspective, it is much simpler for us to first develop a tap-based system for motion capture. We know that tap events are very easy for the Wii's accelerometers to recognize. So, our current conception calls for taking a "snapshot" of the cane's position at the moment when a single tap occurs. If we define cane arc as the angular or lateral diplacement that occurs between tap events, our work is greatly simplified. Without taps, we will have to develop a much more complicated approach to arc width calculation, in which we would have to recognize the moment where the direction of cane movement reverses. That's not impossible to do, but it is probably a lot harder. My thinking is that we should master 2-point touch first, then introduce constant contact later.  The next couple of months are going to include a lot of trial and error as we develop our technology and our pedagogical approach. Nothing is fixed in stone right now, and we need to remain very open to making changes and enhancements suggested by our domain experts and our users. but, we should not abandon plans that were approved by the grant review panel without receiving explicit permission to do so. I also think that its sensible to start with something that we know how to do, get that working, and then move on to them more complex stuff.

On Tuesday, Zach and I will get together to connect his Java WiiCane drivers to the test administration program that I am working on. We should have something nice to show on Wednesday, when I am assuming that we will meet at the office to discuss our plans for responding to the IRB's questions about the test protocols we have requested them to certify.
sl

Progress report on application programming

Zach and I have made progress on the application that will run the WiiCane system.  This application consists of two components:

• The device driver, which Zach is programming in Java. This is a program that will run on the PC mounted to the pole at the end of the course. The driver establishes and manages the wireless connection between two Wii Remote units: one mounted on the cane and the other mounted on the user's body. The driver maintains information on: 
• Linear distance between the starting point and current location.  
• Body compass bearing, expressed as a positive or negative angle.  Pointing straight on the course returns a bearing of zero, and deviation to the left or right returns a negative or positive value, respectively.
• Amount of veering, measured linearly from the imaginary line connecting the start and finish points. 
• Cane taps events. A "tap threshold" is used to distinguish intentional taps from normal accelerometer fluctuations. Three taps in rapid sequence is a special signal that can be used to indicate that the user is about to start running the course.
• Wrist roll. As Gene mentioned, the system will not work if the user rotates his or her wrist such that the Wii remote mounted on the cane is not pointing up at the lights. We can assume that this has happened if the body-mounted Wii places the user in proper position on the course, but the cane-mounted unit reports that no lights are seen.
• Cane arc, expressed as a positive or negative angle of the cane in respect to the body at the moment when a tap occurs.
• The course set up and test administration program, carried out in Adobe Director, which I will be creating. We will use the Moka Xtra to act as a bridge between Zach's Java-based Wii Cane driver and Director.  We have tested this, and it works well, and is very fast, which means that we will be able to respond to user actions without perceptible latency, which would result in system sluggishness. The Director application that we will use for testing in November will include the following features: 
• A user log in screen so that subject parameters (cane height, body width, age) can be set prior to testing, and so that performance statistics can be saved to the computer's hard drive for later analysis.
• A course parameter screen that permits an administrator to customize feedback conditions.
• An animated plan view of the course with an avatar representing the test subject indicating instantaneous body and cane position and bearing during the test. 
• A training administration screen that shows elapsed time and a visual display of feedback prompts currently playing in the subject's headphones. 

These programs are being developed specifically for the upcoming tests. The actual commercial version of the WiiCane product will include other features and a more polished presentation.

wii cane feedback logic and testing procedures - draft

WiiCane procedures for initial testing

The following drafts are for everyone’s consideration and critique.

This weekend I visited Touch Graphics and saw the working model of the WiiCane and course. It is quite amazing. On the HD digital display at the end of the 32 foot course, you can see the cane movements precisely as the cane/subject moves. The equipment and remote software are working and it’s impressive. The user interface and the software to create the feedback loops are the next steps.

I will use the term “detectable” to mean that the WiiRemote can detect the infrared lights suspended above the course.

I will use the term “expected cane tip-placement” to mean that the cane tip lands within a tolerance of 2 inches on the left or right on the surface in front of the subject that is equal to the widest part of the subject’s body’s lateral plane.

These comments do not include procedures for deafblind subjects.

General considerations and concerns:
· The subject may not role their wrist as they move the cane; this will cause the cane to be undetectable. Subjects’ rolling behavior will need to be corrected with intervention.
· The subjects will need to stay with the detectable lateral area during testing. If they move out of this area, the tester will intervene to move then back into the detectable area.
· All subject will align for each trial on the course by squaring-off , placing the back of their footwear into cutouts of a wooden board properly located at the start of the course
· All subjects will wear customized goggles to occlude vision to the point of LP.
· All subjects will wear wireless headphones that are expected to deliver the feedback loop and prevent echolocation.


Logic for creating the feedback loops

VEERING
· When the subjects’ midline exceeds 16 inches from the intended straight-line of travel, the subject will hear a message
· The feedback loop will say the following is high quality electronic speech: “move to the left [or right]”
· The feedback message will repeat each time the subject exceeds16 inches from the intended path.

CANE COVERAGE
· The software will check the subject’s cane tip-placements after the first three lateral sweeps. Thereafter, the software will check the most recent three cane sweeps/tip-placement.
· Feedback will, of course, be issued only if the previous feedback statement has completed.
· The software will select a feedback statement based on the following logic:
- if the cane tip-placements for the three most recent sweeps result in the expected cane tip-placement, then the subject will hear: “Good”
- if the cane tip-placements for the three most recent sweeps result in cane tip-placement further from the subject’s midline than the expected cane tip-placement, then the subject will hear: “Too wide”
- if the cane tip-placements for the three most recent sweeps result in cane tip-placement nearer to the subject’s midline than the expected cane tip-placement, then the subject will hear: “Too narrow”
- if the cane tip-placements on the most recent three sweeps are asymmetrical (not too wide or too narrow on both sides), the greater lateral displacement from the expected cane tip-placement will determine the feedback and the subject will hear: “To wide [or narrow] on the right [or left]


Procedures for conducting trials

For the first trial for each subject, the subject will be have the experiment explained; the testers may use whatever appropriate language is necessary, and take as much time as they feel is reasonable for the subject to understand and be comfortable. Subjects will be asked if they are comfortable with the headphones and the goggles. Verbal and non-verbal response will indicate whether the subject should continue. They will then be walked/guided once down the course, shown the end of the course and the safety obstacle. They will then be walked/guided back to the start of the course. Subjects will always complete trials for veering before trials for coverage.

VEERING AND CANE COVERAGE

· The subject will align at the start of the course.
· The subject will be told to swing there cane and walk forward in a straight line
· The subject will walk unimpeded unless they become undetectable. If the subject becomes undetectable, the tester may physically prompt or manipulate him/her back onto the course from behind the subject.
· When the subject ends the course, they will be walked/guided to the beginning of the course.
· Each subject will complete 10 trials on any particular day, on up to 5 separate days. This number will be doubled at one test site. This procedure will be repeated for all trials for each behavior, veering and coverage.

Course construction complete

This picture shows the WiiCane experimental set up at Touch Graphics' office. The apparatus consists of two poles at either end of a 32' course.  A pair of overhead cables supports a plastic strip that houses wiring and electronics for 64 infrared LED's on 6" spacing.  We added the second cable after observing 8" of sag at the mid-point of the single cable set up; the second cable takes the shape of a catenary (like in a suspension bridge), and hangers drop from the upper cable to the lower one that carries the light strip (like the roadway in a bridge). This ensure that the light strip is flat, and that should simplify algorithms for determining position and cane movement. The second cable also appears to stabilize the light strip and to reduce sway from air currents. Immobilizing the lights is key to ensuring our system's measurement accuracy.

In the detail picture, we see the two cables at the start of the course, a support pole, and the plastic channel that holds the electronics. The underside of the channel is printed with a metric distance scale that will help us to calibrate the algorithm for calculating linear position on the course. To do this, we will mount a laser pointer on the body-worn Wii device, and (hopefully) we will be able to visually observe the red dot from the pointer when it appears on the measurement scale. It's not clear whether this scale will be of use in an actual Wiicane product.

We have tried out the apparatus in our office with a Wii device mounted to a cane, with very promising results: as we walked along the course, the system was able to easily see the lights.  We could watch the lights moving on the video screen we had mounted on the goal-end pole, and it seemed to work for cane swings that were quite wide. The only remaining problem, in my view, is that the user must not roll his or her wrist while running the course, because then the camera is not pointed up at the lights, and we lose position awareness. But, since our second (body-mounted) Wii device will always tell us where the traveler is in relation to the lights, we will know that  wrist rotation has occurred if the person is under the lights but the cane-mounted Wii doesn't show any lights visible. Then we can provide spoken feedback to encourage the user to straighten his or her wrist, and we can let them know when this has been done successfully before resuming travel.

discussion about pole placement in the coures

Bonnie responded to my last post via email, so I am pasting that  here, along with responses from Dona, Gene and Zach.  I want to make sure that our discussion is captured in the blog so that we end up with a nice record of our process.  The question of sagging has been taken care of by adding a second cable above the one holding the lights. think suspension bridge.  the upper cable takes the shape of the catenary, and the lower cable, the one holding the lights, is perfectly flat. 

(In physics and geometry, the catenary is the theoretical shape a hanging chain or cable will assume when supported at its ends and acted on only by its own weight. Its surface of revolution, the catenoid, is a minimal surface and will be the shape of a soap film bounded by two circles. The curve is the graph of the hyperbolic cosine function, which has a U-like shape, similar in appearance to a parabola.)  Click here for more information about the catenary.

Hi Steve,

I am just now reading the blogs about the overhead string of LED lights and the belt mounted Wii remote. Sorry it took me so long. As others have commented, getting rid of the path off the floor seems like a big improvement. I like the idea of the Wii remote being in the center of the user's back as it won't interfere with cane usage.  It sounds like you will be able to get more accurate feedback about cane arc with the overhead system.

 

Have you been able to set up the cable and poles and try it out yet? I'm curious about the length of a path, considering that sagging may lead to inaccurate measurements.  If you can't get anywhere near the 30 feet length, would you envision two strings of lights with 4 poles in order to cover the entire 30 foot path? 

 

Gene & Dona, what do you think would be the impact of having a pole in the path of travel and at the end of the path? Do you think any of the subjects would be able to use echolocation to hear the poles? I'm wondering if the poles could be used as cues for alignment in a way that might interfere with the veering data, which was designed to have no audible markers, so to speak. I read that the pole will be padded, which is good because I imagine some of the younger subjects or those who are not covering their body width bumping into a pole. Do you bumping into a pole would result in the person altering their gait or cane width as a response to contacting a pole? This is the real world. When my students bump into something because they were not covering the entire width of their body (or not paying attention, or cane hand not extended), they often will respond by swinging their cane wider. Some students will slow down because they are now aware there is an obstacle and they want to avoid contacting it. A slower speed and having to move around the pole could affect the subject's straight line of travel.

 

I'm trying to view this pole idea as a positive learning experience from an O&M perspective. If it is the best way to collect the data (cheaper, appartus readily available, easy to ship/assemble) then there just needs to be consideration of how the pole(s) might alter the subject's cane usage. There are obstacles in the environment so maybe the experimental design is now revised to include an obstacle. If it works out that we only need a pole at the beginning and end of the path, they my points may  not be relevant. I'm simply thinking aloud as to how a pole IN the path might alter the subject's cane usage and alignment.

 

Thanks.

Bonnie 

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From Dona:

Wow, Bonnie, interesting points!  I hadn't thought about the possibility of the goal pole serving as an aid to aim for, or the effect of having an obstacle in the line of travel.  perhaps two things could be done to mitigate that:

1. Surrounding the pole with spongy cushiony material should make the echolocation very difficult (even with clicking );

2. Having a line run perpendicular to line of travel a few feet short of the pole will warn the user that he's reached the end.

-- Dona

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From Gene

Bonnie,

Subjects' vision and hearing are occluded.

A pole in the center of the course would not work. I believe that the 32 foot course will have a single suspended string of lights. The poles are anchored at the top and bottom.

The single forward pole at the end of the course should not interfere at all. It will be padded, of course, and subjects may encounter it when the course is completed.

Does that all make sense.

Gene 

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From Zach:

I was also skeptical about keeping the line taut but I've seen it at
Steven's office and it looks great.

The starting pole will have a wood block or similar on the pole or on
the floor to help subjects square off.  Both poles are wrapped in foam
to prevent injury.

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From Bonnie:

Gene - I obviously forgot about the subject's hearing being occluded. That sure eliminates my concern about echolocation. Yes, your comments make sense. I had thought they couldn't string the lights for the entire distance, hence a pole in the middle of the path would be needed. So my concern no longer apply!

Zach - I am glad that the line can be kept taut for the entire distance. This eliminates the pole in the middle. I'm excited that Steve has set it up and it works.

Dona - I like the idea of a textural change in the floor a few steps before the end of the path to let folks know they have reached the end and the pole is near.

Thanks.

Bonnie