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Mockups!
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Presentation Video
Demo Video
Concepts
Instrumented Knee Brace
A functional knee brace with electrical stimulation, range-of-motion detection, and muscular force feedback for a customized rehabilitation experience
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Contributors
Tolu: mechanical structure, 3D printing, sewing, CAD, presentationChristian: electronic circuitry (EMG & ROM), presentation, assemblyGui: mechanical structure, 3D printing, assemblyLogan: mechanical structure, hinge mechanism, CAD, assemblyAquila: electronics testing (EMG), user interviews, data analysis, sewingSusan: electronic circuitry (EMG), user interviews, sewing, presentation
Reviewer Feedback
Atissa Banuazizi
Concept
For the sketch model, you focused on users who might not have access, or be able to afford, regular physical therapy; now, it seems that Stim-Brace would enable users who are already working with a PT to get feedback on their exercises when they’re not under direct supervision, and to share data with their PT. I think there are good reasons for this shift! But now the PT should certainly be thought of as a user, as well, in the sense that you are enabling PTs to do their job better and offer more informed care – which means it’s really urgent for you to talk to *those* users, and to figure out exactly what their needs are. How much do they want this data? What concerns might they have? Would the PT be responsible for tailoring the feedback to the individual, and how often would they need to do this?
Analysis
See above: I think there are risks that you just can’t know without in-depth info from the professionals.
Execution
The mockups did a nice job of answering the questions asked, and you presented the data well.
Ellen Roche
Concept
I mentioned this during the live demo but I see a lot of value in measuring neural function post injury/surgery, but this needs to be done in the right way, and if you are using EMG to longitudinally quantify neural function, it needs to be very consistent, and might need to be performed in combination with a nerve conduction study. I think this is maybe a parallel path to ROM measurements and it might be easier for you to focus on one or the other and get it right. A neurologist would be helpful if you are going the route of quantifying neural function post-injury. For ROM it would be good to speak to a PT or orthopedic surgeon if you are looking at a post-surgical recovery. I know you will talk to Dr. Crandell, If you are looking at neural function, talk to Hugh Herr's group, they do a lot of nerve recordings and measurements. Let me know if you'd like introductions to anyone in the group. This study shows surface EMG monitoring of recovery of the upper extremity post-stroke is feasible https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8589300/ - so perhaps this would translate to the lower extremity post-injury - but needs a lot of research. Here is a wearable with incorporated sensors for the upper limb https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7412666/ There are some standards here https://www.researchgate.net/profile/Hermie-Hermens/publication/228486725_Standards_for_suface_electromyography_The_European_project_Surface_EMG_for_non-invasive_assessment_of_muscles_SENIAM/links/09e41508ec1dbd8a6d000000/Standards-for-suface-electromyography-The-European-project-Surface-EMG-for-non-invasive-assessment-of-muscles-SENIAM.pdf
Analysis
If you are applying stimulation, especially with a DIY neural stimulator (TENS/NMES) there are a lot of risks that need to be clearly identified.
Execution
Your demonstration of EMG sensing and combination with goniometer showed us that you can make either work - now it's time to crystallize your concept and conduct user interviews.
Rich Wiesman
Concept
I am concerned that your product concept is a form of medical self treatment that may not be advised by medical professionals. When I asked if the team had feedback from physicians or PT's I got a sort of weak answer that you had spoken with a sports trainer at MIT. You really need to reach out to orthopedic specialists (several) and understand if this sort of product fills a real need among many recovering patients. I realize that you may feel that this product could have helped one or more of you with an injury recovery, but you still need input from a number of professionally qualified medical experts who can advise you on the safety and need for this sort of device. Could a user actually do harm with this brace and the feedback without a physician's or PT's judgement and interpretation? I am not familiar with the details of an ACL injury recovery. I have some indirect knowledge of the recovery from a knee replacement (which also involves PT to regain (and keep) full motion). Frankly, for knee replacement I'm not sure if the feedback would replace the direct observations of a PT or a physician who is also checking other aspects of the surgical recovery. Put another way, does the patient need to be observed for additional reasons which might reduce the importance of the brace. I was further concerned during the demo when someone mentioned that this might replace PT appointments if the user didn't have insurance or if appointments had run out. Again, this sort of venture into self-help medicine should only be taken if you have good professional advice from physicians and PT's. Then you can hopefully use one or more of these same professionals as product advocates who will advise you as you develop the prototype.
Analysis
While your design had progressed significantly from the sketch model; without feedback from at least a few medical professionals I feel that your risk identification is not complete. Could a user do damage to themselves with your device? Is electric muscle stimulation always beneficial or even OK? How will the brace be purchased? If you are counting on medical insurance compensation then there will need to be an evaluation by insurers and they will determine if the brace offers a cost-effective improvement in care. That is, the brace will need to offer the same or better care than currently compensated therapies for the same or a lower cost.
Execution
As I mentioned earlier, the mockup model showed much more than the sketch model. However, I was confused by the repeated mention of "force-feedback." I did not see any force being measured. Are you claiming to infer muscle force from the level of electric stimulation? If this is the case then you have a great deal of experimental work to do to verify this sort of correlation.
Charlotte Folinus
Concept
From speaking with you at mock-ups, this sounds like a concept for post-acute recovery after surgery, and it would be always/almost always worn. The goal is to have it work as a brace that can do TENS and monitor both ROM and EMG. It wasn’t clear to me how frequently ROM and EMG measurements need to be measured to be useful for your patients and clinicians, or how accurate they need to be to be useful. Goniometers seem generally repeatable, but how repeatable/accurate would your ROM measurements be as strap position changes? EMG tends to be very sensitive, is tedious to set up properly, and produces noisy data. I’m not a physical therapist myself, but I have experience interviewing/working with prosthetists and physical therapists — a common theme I found is that data for data’s sake is generally not the most clinically valuable approach, but data can be valuable for supporting clinical decision-making. I imagine a CSV file or raw ROM or EMG data may not be useful for your patients/clinicians, but perhaps insights from that data could be useful — how much time are your PTs willing to spend looking at the data? What types of insights/metrics would be most valuable to them?
Analysis
Who currently pays for knee braces for patients like the ones you describe, and what would they gain from a (likely) more expensive knee brace with additional functionality? I know that knee braces count as durable medical equipment (DME) and can be reimbursed through insurance (but are not always) — do insurers have regulations for the safety/durability/performance/etc. of knee braces?
Execution
Your mockup has grown since sketch models, and it seems to mostly do the things you’d like it to do. I encourage you to keep thinking about the repeatability and what the overall user experience might be like (your users might be both the patients and PTs! they may have different/overlapping needs and experiences).
Rebecca Thorndike-Breeze
Concept
Knee brace: At the live demo, we discussed the need to work closely with Physical Therapists beyond MIT -- I suggested contacting Joint Ventures, which has a Kendall Square location. I know you didn’t test for electrical muscle stimulation for mockups, but if you do want to develop the concept for TENS/NMES stimulation, you’ll need to be in close collaboration with PTs who have extensive experience with this kind of muscle stimulation. In the presentations, I did not hear much about user testing or about user frustration with the current brace design, though this information was included on the slides. What didn’t they like? What hurt/irritated their skin? What form factors did their feedback suggest to you?
Analysis
No feedback provided
Execution
No feedback provided
Daniel Braunstein
Concept
I'll comment on concept, analysis, execution in this single block. I understand this to be post-surgery, always worn device (during recovery/rehab). I was happy to hear about the progression from sketch model to the present implementation. Clearly, there have been developments. Earlier, you showed a knee brace with some stimulation device and velcro - I can't say I understood that. Your current version evolved into a device to measure range of motion, measure EMG as a proxy for force (I think?), and therapy delivery through electrical stimulation. OK. The gap, for me, is I didn't hear whether or not this has the potential to provide any therapeutic benefit. I was waiting to hear about the dozens of clinicians/PT etc whom helped guide you decision making. I caution you about getting too enamored with an instrumented "anything" unless it is backed up or informed by input from experts in that domain. Because of this, while the concept is clear, I didn't rate this highly on strength. It needs more input from the clinical community. If you have this input, then, by all means, keep on trucking. If it remains conjecture, you have work to do. Having said this, my non-expert opinion on the efficacy can imagine remote logging and trending of range of motion as interesting and useful data. If a PT or doctor could remotely look at statistics on ROM including number of bends, rate, and range, then perhaps they could monitor progress. An email: "I notice you are not bending beyond 20 degrees, like we discussed last week. You should come in so I can take a look." or some such dialog. I do have experience with EMG sensors, and while there is something alluring about "measuring muscle activity", they are insidious little devices that are very sensitive to placement, adhesion, preload, electrical noise, etc. etc. I'd avoid them unless there is a compelling medical reason or requirement that this be a muscle monitoring device too. Getting useful information from the EMG sensors when the patient is also the lab tech is a tall order. Other: Think about human factors, comfort, cleaning
Analysis
No feedback provided
Execution
No feedback provided
Dave Custer
Concept
Your concept fits my understanding of where the medical world is headed, so a brace that supports, collects data, delivers therapy, talks to the internet... is something we'll all be wearing in 10 years when we ding our knees. Your current angle measurement seems like a slam-dunk; that part of your design doesn't worry me. Instead, me concern is getting useful data over time from an EMG sensor. My experience in the 2.671 lab tells me this measurement is fiddly. Are there peer reviewed papers that document other consumer products that obtain reliable EMG data? From these papers, would you have reason to believe your widget will work? Can you put numbers on the specification of the 4th need?
Analysis
I don't get any sense that you are fanatically driven to make sure the brace does no further harm. Are there standards for knee braces? For TENS simulation? Are there papers on knee brace failures? Law suits regarding knee braces that you can track down through the MIT libraries? A basis for your concept in the literature would go a long way towards making me think I won't get hurt when I put on your brace.
Execution
The mockup is a good step in the right direction. Perhaps though, further hard questions deserve to be answered (e.g. repeatable EMG measures).
Sonic Fire Extinguisher
A targeted, low frequency, acoustically driven vortex cannon for putting out fires
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Contributors
Gaby: cannon, materials search, sound lens, experimenting leadNico: cad/3d print, speaker, wood platform, key findingsTrevor: equipment diagram, materials search, cannon, sound lensDiane: cad/3d print, speaker, experimenting, critical risksCarly: wood platform, experimenting, user research, mockup goalsChristina: sound lens, experimenting, user research, product contract
Reviewer Feedback
Atissa Banuazizi
Concept
The concept and user are clear. Feasibility still a question mark.
Analysis
I was confused about the item in your product contract that said that it would turn on at 450 F (the temp at which grease burns). But would the product (up in the stove hood?) be able to measure the temperature of the fire itself, or of the air above the fire? And if the latter, wouldn’t the air temperature depend on the size of the fire? Will be really useful to test with grease fires to see how they burn/spread/are extinguished differently.
Execution
Your mockup was constructed well, and it was a lot of fun to watch the demo! You were very clear about what you took away from it – but it did seem like you learned more about “what this particular model is capable of in this particular situation” and not as much about how the principles work in general.
Ellen Roche
Concept
Sonic fire extinguisher - the mockup helped a lot to identify how the tech would work, and see it in action. I think having a clear product vision here would help - during the live demo you mentioned having it mounted over a hob - this is great - show us the vision! Then think about how it would be mounted, powered, what risks would be involved etc. Testing it in real life scenarios with grease etc. would obviously be necessary as you move forward. A lot of progress since Sketch Model.
Analysis
As mentioned above, there are risks that need to be addresses such as testing with grease fires, mounting in the envisioned setting etc.. Analysis of different frequencies would be super helpful. How would you show this is better than existing fire extinguishers (fire blankets, chemical fire extinguishers etc.). Look into the past 2.009 project on sensing a fire on a hob - if that tech existed could you automate triggering? Would this add more risk/complexities or greatly increase your value add?
Execution
I commend you on the execution and on working with us so carefully to make it happen in a safe way. I know Rich has mentioned potential risks with alcohol fires so moving forward we can look at alternative ways to create the fire (most likely in a real life grease fire setting).
Rich Wiesman
Concept
I believe there are some fundamental issues with your product concept, and you need to explore the science and/or do a few new tests very soon if you decide to look into this further. You will find many articles and similar tests on acoustic fire extinguishing. You may also find that lower frequencies may be more efficient, but the waveguides to direct the acoustic energy may not scale well for most practical applications. It is my understanding that there are two basic ways to extinguish a fire - cool the combustible material below the ignition point or deprive the combustion of oxygen or fuel or both. You chose to test with alcohol which vaporizes at a low temperature and is known to be easily extinguished by even slight air movements. I suspect that the clear barrier around your test fire was there to prevent wind from blowing out the fire. The flame was vaporizing a thin layer of alcohol and when you blow that layer away the fuel is cut off from the heat. You might find that testing with materials like wood or paper or even grease will yield very different results, since these may need more energy to separate air or fuel from the heat. Please look at the many experiments that you will find with just a few minutes of searching and develop a physics based model for your approach. The thing you need to understand is what it will take in power and physical structure to scale your approach for practical application you have identified.
Analysis
Unfortunately, you did not seem to develop a sound model to explain your approach and how it would scale for other sized fires and for other fuels. You seem to have essentially repeated an experiment that was described by many including some students at George Mason University. Your frequency conclusions were experimental -- not based on models and analysis. Your experiment was limited by the hardware which showed a natural roll-off in output amplitude as frequencies dipped below 30Hz. Lower frequencies may have actually worked more efficiently to extinguish the small test fire, but the wave guide or nozzle may have needed some adjustment to support a lower frequency. Again, all of this needs to be properly modeled. If you don't have time to develop your own model then please look for good models from other reputable sources. I believe DARPA attempted to investigate a similar approach to fire extinguishing and you might look into whether those results are available. https://www.cnet.com/culture/darpa-drops-the-bass-to-extinguish-fire/
Execution
Your mockup work seems to have reproduced a number of similar experiments by others from over the last 10 years. I've already commented on why alcohol might be unusually easy to extinguish with this approach. If you test again with alcohol, please be aware of how dangerous an alcohol fire can be because it has little color and can spread without being seen. Alcohol fires are a known issue with certain racing fuels. While the model was a good way for your team to try the basics of what other experimenters have reported, without adequate modeling and analysis of the process you still don't understand the limits and how the energy and structures (wave guides) will scale to meet larger fires and other materials.
Charlotte Folinus
Concept
Very cool concept with a reasonable understanding of who your customers are. You mentioned that there might be some involvement from the user in either activating or moving the device into place. While there are questions about the technical feasibility of the concept, it might also be nice to keep thinking about how this might be safer/easier for the users than other extinguishing methods.
Analysis
Knowing little about sonic fire extinguishing myself, I’m curious what the sensitive variables are — how precisely positioned does the opening of the funnel need to be (both XY plane and height away from the flame)? how much energy or power do you need to put out a fire? How does this depend on the type or size of fire? Even if your findings are approximate for right now, the physics-based reasoning could provide insight. Related: If you blast some sound wave with a certain power at the fire and it doesn’t extinguish, what happens? Would this also need to contain some other (albeit more destructive) fire extinguishing mechanism?
Execution
This was a nicely-made mockup, and it seemed to give you the freedom to test out a few different aspects and use the mockup as an experimental tool.
Rebecca Thorndike-Breeze
Concept
Fire extinguisher: I don't quite understand why this is targeting commercial kitchens -- the need for a clean solution to extinguishing fires was implied. Instead, I was left with the impression that the motivation for extinguishing fires with sound was because it was a fascinating idea -- cleaner, yes, but also "sci-fi." What have cooks/chefs/restaurant owners had to say about fire extinguishing in their kitchens? How much damage does extinguishing fires using existing methods cause?
Analysis
The db level is an interesting problem with this concept. It will be worth testing user experience of the sound. In your slide presentation, you note that the dbs are quieter than a motor cycle…but motor cycles are quite loud. Here more precision and research will be useful, as well as user testing. According to your key findings, fire in a pan is easier to extinguish than in a pot…how does this intersect with likelihood of fire in commercial kitchens? More user research is needed to understand the problem and scope your concept. How likely is it that you’d need to extinguish a fire in a pasta or soup pot? Your next steps don’t seem to be directly informed by your mockup findings, since your experiment was only at 25% of your max power, but in next steps you want to integrate a pre-amp for more power. However, I may have misunderstood -- perhaps you meant you need a pre-amp to get closer to the max power? But overall, as other reviewers note, there’s a lack of quantitative understanding in these experiments, particularly with regard to the maximum fire size you can extinguish.
Execution
No feedback provided
Daniel Braunstein
Concept
I'll comment on concept, analysis, execution in this single block. I cannot get my head unwrapped from the two George Mason students who did this exact project seven years ago. And who also managed to extinguish a small alcohol fire. Soooooo......what happened in that case? Did the concept progress? Why or why not? What techno-nugget have you stumbled on that will help you advance this beyond the George Mason project? At sketch model, we all asked about energy and power - this seems a critical (and obvious) question. Yet, there was no further clarification during this review. Please dig into this topic. The actual construction of the mockup was pretty good. The use of 80-20 was appropriate.
Analysis
No feedback provided
Execution
No feedback provided
Dave Custer
Concept
If the concept can be made to work, it is brilliant. The "if" is a big "if." Are there other niche fire extinguishing uses that might be easier for your sonic idea?
Analysis
My sense is that your work is not being guided by the underlying physics of putting out fires. Can you make a spreadsheet whose inputs are things like heat capacity, temperature, flame area, audio power, distance from flame to extinguisher, frequency, etc and predict whether a fire will be extinguished? Are there better ways of generating 35 Hz plane waves than using audio amplifiers/speakers? Would a higher frequency wave in a 35 Hz envelope do the same thing as a 35 Hz wave? I am concerned by the absence of citations from the literature. A quick surf of google scholar will turn up previous work. Does this previous work make you confident moving forward with this concept?
Execution
From the mockup, I don't have confidence that the concept can be scaled up to work on kitchen/grease fires. What y'all learned, I can't tell.
Assistive Gripper
A handheld gripper for users with with limited hand strength and dexterity
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Contributors
Megan: user interviews/slides/scriptMatt/Chad: reliability testing/ratchet construction/CADKwame: gripper mechanism design/endifector design + construction for bothJack: user interviews/ratchet design help
Reviewer Feedback
Atissa Banuazizi
Concept
I’d look forward to seeing you get more information from your users – not just from interviews, but by observing them picking things up with and without grippers! Depending on whom you approach, their ability to manipulate the rod and disengage objects from the gripper may be greater or lesser; you may find that wheelchair users have different needs from the elderly or those who only have compromised manual dexterity. (Will any of those user groups have trouble positioning the gripper directly over the object if, for example, it rolls under a table?) I’m also curious how it would operate on, say, a shag carpet, or outdoors on grass.
Analysis
I think your product contract could be sharpened up a lot –I don’t see that your attributes and specs are particularly well aligned yet.
Execution
I enjoyed fiddling with your (surprisingly lightweight and effective) model! Good job testing the robustness of the adhesive; I’d have liked to see a broader range of items you could grab with the grippers (especially weirdly-shaped ones).
Ellen Roche
Concept
Clear concept and strong idea - want to make sure it's better than existing products.
Analysis
It would be great to do further analysis on the adhesion strength and lifetime of your silicone substrate. It works well, but now you should think about testing in worst case scenarios (what if it gets wet, dusty, dirty). How does it perform over time...I work a lot with soft robotic grippers and adhesives. We have lots of quantitative test methods (peel test, tack test, lap shear test) to quantify adhesion and to create microstructures to enhance adhesion (our work is mainly for tissue adhesion). Prof. Zhao in MechE does a lot of tissue adhesive and Prof. Jeffrey Karp does a lot of gecko inspired adhesive. TA Sam Gollob has expertise in soft actuators and grippers and silicone molding if helpful. Please don't be shy to ask for lots of help if you move forward with this.
Execution
Big improvement in mechanism and prototype, the telescoping and gripper-in-gripper modules were much appreciated. Alberto Rodriguez does a lot of work on grppers too. There's a pick and place test that is typically used to compare different types of end effectors and designs that could be useful as a test to iterate through designs and to benchmark to other available designs.
Rich Wiesman
Concept
The pickup tool is an interesting product concept. If one looks at available products it is easy to see many different mechanical grippers for reaching high shelves or picking up items from the floor without bending. Magnetic pickup tools are also plentiful and found in most mechanics tool boxes for retrieving fasteners that have been dropped into areas that are difficult to reach into. In fact, I used to have a telescoping tool that combined a light and a magnet (for retrieving dropped screws and similar items). The so-called adhesive pickup element was the portion of your concept that I found particularly interesting. Grippers for retrieving dropped papers and cards and similar things are not so common. How would someone with mobility issues pickup a dropped cell phone? A cell phone isn't magnetic and it would be difficult to grip with mechanical finger type devices. I understand your concept for using an adhesive, but when I saw your device it made me think that you are using the silicone adhesive properties in combination with some interesting mechanics to use opposing shear forces to create a normal gripping force. I believe you had some of this acting through the angles of your adhesive pads when you pushed them down on an object. Take a look at the DARPA program that developed gecko-like foot pads to help a person climb a glass wall (https://www.darpa.mil/news-events/2014-06-05). You may already be doing something like this to create a novel gripping tool.
Analysis
You've done a pretty good initial job of looking at your initial product specs and how these meet your customer needs. One of my concerns is that you might be trying to combine too many functions into a single device. I'm specifically talking about combining things like magnetic pickup and large mechanical gripping with the smaller "sticky foot" sort of pickup. If yo can do this efficiently in one tool head that's great, but be careful that you don't compromise all functions for the sake of trying to include everything. My other concern is that a magnetic pickup can grab lots of things that you don't want to pickup. And, a magnetic pickup can be messy to attempt to clean as it picks up lots' of small shards of magnetic material. I also like the testing you did with the adhesive material and fact that you included testing after washing the material.
Execution
You created a nice mockup model. The testing was good, the test results were honest and meaningful, and model informed how future iterations might advance.
Charlotte Folinus
Concept
I understand who your users are. I’m not sure I understand the current pain points (types of items) that they struggle picking up off of the ground (but I know they are there!) — keys and paper, ok. What about pills or something fragile/delicate? If small objects are being picked up with the adhesive, does the adhesive leave a residue? (ex. if pills are a pain point — if someone drops a pill, can they pick it up and still take it?). Some of your slides mentioned picking up "things" -- being more specific about what the objects are could provide additional clarity.
Analysis
You want to support 1kg objects — can you assume that the object’s center of gravity is aligned with the shaft of your gripper, or would it generate an out-of-plane moment? This probably depends on what objects are being picked up, what their geometry is, and how easy it is to align the claw part (I struggled with this part). If objects’ CG might be off-center or the objects are unevenly shaped, perhaps a 3D gripper geometry could help support these off-axis loads.
Execution
Your mockup is nicely elegant. You could consider using compliant or soft elements (or a more complex rigid body, linkage-based design) to give additional freedom at the tips of the jaws — it seemed like most of the gripping was coming from the silicone piece vs. the gripper itself. In the current vision, the gripper supports the weight of the object through friction/normal force at the contact. As you increase payload or use unevenly-shaped objects, will you be at risk of not picking up the object or breaking either the object/gripper There are many compliant grippers and soft robotic grippers — these could perhaps be another source of inspiration.
Rebecca Thorndike-Breeze
Concept
gripper: The user can be more specifically defined. For what it’s worth, here’s a quick article about why you should not use the phrase “differently abled,” with some other options you can use instead: https://www.betterup.com/blog/differently-abled Also, the more specifically you define your user needs, the better you will be able to design a product to add value to that user’s life. As presently defined, I am not convinced of the need for this product. At the live demo, one team member told me that your target users have difficulty actuating the current grippers in the market, due to a variety of conditions that limit their grip strength. What specific conditions affect grip strength and the ability to bend and reach? Finding answers to these questions will give you a sharper understanding of your user base, and point you in the right direction with regard to interview questions and components to test with users.
Analysis
No feedback provided
Execution
No feedback provided
Daniel Braunstein
Concept
An assistive pickup device for people with limited dexterity. Got it. The array of available reaching tools indicates the space exists. You highlighted how you differentiate yourself from others - that is good. The sticky silicone and clever plunger/lock/actuation is well....clever. I am concerned about the life of the silicone. This needs more characterization. Perhaps you can provide a kit of replacements? The claw device wasn't doing much in picking up the items I was playing with. The geometry needs tweaking (which I know you know). Consider compliant tips or fingers that allow for more positive engagement. Look up Salisbury hand (Ken is retired faculty at Stanford) - for some reason, I'm reminded of that. I acknowledge the progression from your first sketch model to the current mock-up - smaller, more refined mechanism, more robust. So, good progress. Perhaps you can make a few of your device, purchase a number of existing reaching devices, and test, test, test with users.
Analysis
No feedback provided
Execution
No feedback provided
Dave Custer
Concept
The use and user are clear. I think there is potential for your grasper to be more generally useful for picking things up off the ground without having to bend over. An advantage of your particular use case is that an individual could adjust their grasper to optimize picking up things they are accustomed to dropping. Alternatively, users could alter the possessions they always drop to be easy to pick up (for example, glue a magnet on everything...). Such customization is not possible for the person who is trying to pick up litter that could be any geometry/density.
Analysis
I can't tell whether this concept would be too expensive, too complicated, and/or too difficult to use. For the time being, it looks fiddly.
Execution
The mockup does show that multiple grabbing methods are possible. The ability to switch-up the aspect ratio was interesting, but I don't know how important that is; that seems novel to me, and I wonder if there is an opportunity here. I didn't get a sense of what the mock-up has taught you and how your building will guide your choice of what concept to pursue.