2.009 Product Engineering Processes

Results of Technical Review

To view a team's prototype and provide feedback, click on the links provided below.


IV pole


camera toy


Braille teacher


stall door opener


kite game


brace tightener


rappelling device



General comments
Please read these comments thoroughly.

Over 45 instructors and guest reviewers attended the review. Team specific comments from Professor Wallace are written on this page, below this section of comments for all teams. You will also receive longer written instructions from other instructors before your team's lab this week.

Teams have shown good progress since the mockup review. The current prototypes are great platforms for testing, and they are a concrete reference point/architecture from which one can carefully design and detail a "productized" alpha prototype.

While some were more refined than others, across all teams the current prototypes are closer to an engineering mockup than a designed product. There are still significant challenges and design resolution on route to a looks-like, works-like prototype and final presentation.

It is now critical to design and execute your device as coherent, integrated, elegantly-resolved products, thinking carefully about efficient use of materials, ease of fabrication, cost and user safety, overall form, and human factors (amongst many other things). This is where the transition to being the design of a product, not just a concept, takes place. Please think about how your current prototype would need to change to be comparable to a product that you can already buy. It is often helpful to look at details in related, real products for inspiration at this point in the design process. This is what we are aiming for.

If your team has key functional aspects or system integration issues yet to be resolved, it is very important to tackle these problems soon in order to avoid surprises a few days before the final presentation. The core, integrated functionality should be solidly resolved before the Thanksgiving break so that there is time for implementation, planning, testing, and preparation/practice for the final presentation.

Use your current prototype well to test and understand how to resolve challenges. As noted in the lab notes for this week, it is critical to keep things moving and have your next design revision worked out before the break. Your team will have a 30 minute design review with course instructors next Monday afternoon (23rd).

All teams should aim to have the prototypes completely ready and available for presentation practice by the Saturday before the final presentation at the very latest.

Your team will need to take a split approach during the final weeks, working on the prototype and at the same time designing/preparing materials for the final presentation. A large number of product development professionals, plus many of your peers will be in attendance and will review your product, so it is a terrific opportunity.

The Team-specific comments/suggestions below from Professor Wallace are intended to help each team in preparation for the next design revision. Please consider these comments before setting priorities before the holiday, and feel free to ask if there are questions. I hope to discuss design details more when we meet on Tuesday, Wednesday, or Thursday this week to talk about your final presentation setup. Please contact Professor Wallace to schedule a time for your team if you have not done so already (often during the later part of lab works well).

Finally, the average score from reviewers for each prototype, with standard deviations, is at the bottom of this page.

Team-specific comments and suggestions
red, green, blue, yellow, orange, purple, silver, pink

Red: IV pole
View the prototype and provide additional feedback

The prototype pretty much works and allows you to really test, which is great! With this reference, it is now time to make it into a product. It should be beautiful outside to the user and on the inside to the engineer. Be sure to use what you have to test it with users (in real use environments) to understand potential issues, what is helpful, and what is not. Also, try to avoid feature creep—understand what it really needs to do and do that well. First and foremost it needs to be a good IV pole! You might want to develop and set up a standard obstacle course for testing.

Some additional comments follow.

  • think about the architecture of the product carefully. It should be possible to move from a platform with a cover to using the housing/form of the product as part of the structure and mounting device. There should not be proto-boards in the final product prototype, and components should be realistically mounted.
  • think about how to make the device look clean and friendly, maybe even a bit organic. It should have a coherent style. Perhaps use a dominant feature, such as the status lighting concept as inspiration for thinking about the entire form.
  • should there be a manual over-ride? Perhaps if you touch the pole it goes to automatic mode?
  • can the device start in a neutral position so that a user can back up or go forward when they start, and the behavior is always the same for a given input?
  • the motion of the device was pretty jerky and jumpy. It seems like softer starting, stopping, and motion changes would be desirable.
  • catching the IV line on things seems like a concern to work through carefully.
  • with large wheels it should be able to go over obstacles like thresholds pretty easily. Is the degree of suspension on this prototype really needed? If yes, then can this be simplified/refined?
  • should this device be quiet? It seems like it should.
  • be sure to account for cleanability, charging, and all of the other things that it needs to do as a real product.

Green: Braille teacher
View the prototype and provide additional feedback

You have a direction and vision that seems quite interesting as a product. Now is the time to make it a really special product for its user! Continue to work with experts, but at the same time avoid feature creep or duplicating familiar teaching devices. Know your core proposition and do it really well. It seems that a clean device that prompts with characters with little input/minimal interface other than the character is compelling.

Some additional thoughts are:

  • for the internal mechanism, the linear actuators seem pretty nice but the Braille pins should be completely guided by a support/bearing structure, and the actuators should only move pins up and down and see no other load.
  • it will be a tolerancing challenge if each Braille pin/actuator assembly is individually mounted into the enclosure. Consider designing the single housing to include all of the features needed to rigidly hold the actuators and pins in place. 3D printing seems appropriate, but the Objet Alaris will give better finish for bearing surfaces, and final finishing as well.
  • once you have your circuit design resolved, be sure to have a printed circuit board made and soldered connections. Proto boards are a very common failure mode, especially for something that will be carried and moved a lot during testing.
  • The design of the product form is really important. How does this become a special and meaningful friend for its user. It seems like something a user could really bond with. Something they want to have with them to learn and practice when opportunities present. Maybe special like a phone might be for many users. I keep thinking of a beautiful rounded, smooth device one might carry in a pocket, just because being able to touch it feels nice. Is the inspiration for the device something that goes into a pocket? Is it worn with a tether on the wrist, or is is more like a joystick input device with wrist rests so that it is comfortable to use on a desk top? Use whatever the use model is as inspiration to refine the form and key dimensional parameters and features of the product. Make it beautiful both inside and out.


Blue: kite game
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This seemed like fun! I think that there are a couple of key things to taking it to the next step. The kite and electronics need to get lighter so that the kite can fly in more modest winds. Also, stronger status feedback about what is happening will improve game play and allow spectators to understand as well. On the kite, the release needs to be minimal and refined, both on the outside and inside. The striker had good thoughts behind it but also needs refinement. With this concrete prototype, there is now a good reference to work though refining and designing the product prototype.

Additional thoughts follow.

  • a larger signal to see strikes would help. Could it change colour based on status? Could there also be a distinct colour status change when it is falling? Could the striker also make confirming sounds about the kite status?
  • the form of the striker has evolved nicely. The trigger travel seemed small and did not give a clear sense of when it was pressed. A number of sound cues were thoughtful, but need to be louder and more pronounced. It would be cool if the striker had an auditory aiming signal (could give sound feedback when on target... requires 2 way communication).
  • for the kite release, want to now move it past the reuse of found objects. To reduce weight, can a soft foam case be the enclosure and mount for the release system?

Yellow: Rappelling device
View the prototype and provide additional feedback

The two prototypes were nicely made and excellent testing platforms! It seems like your performance goals are challenging but should be attainable, but please use the existing prototypes to really understand what is happening. Otherwise, you could spend a lot of time making changes chasing something that you hope will work better. Tweak and test, tweak and test and time's up before you know it. Before going into a long rebuild, be very confident about what needs to change to make it work.

Some other thoughts and suggestions follow:

  • The shape of the jamming cam mechanism is really important. The cam shape used in the open concept is closest to what I picture being desirable when I think about a free body diagram. When drawing the force vector from the contact point on the rope to the pivot, any horizontal force component (from squeezing the rope) that is above the pivot is a moment working against jamming. I imagine this to be especially important at initial engagement. Ideally, it seems like the contact point would be just before the cam "pops through" to below the pivot.
  • resolving how to easily attach the device to rope, and how to be able to see that it is clean, functioning well, etc. seems important.
  • from a fabrication standpoint, casting seems risky, especially from a prototyping point of view. CNC machining from billet material might be appropriate.

Orange: Camera toy
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A lot of work has gone into the different components and sub-systems of the toy. That said, all of the major elements have a distance to go to be working, and an even bigger jump to become an actual resolved product design. When I think about it, in effect I see two, and perhaps three products—a viewer/binocular, an app, and a walking robot. Any one of these could be thought of as a product... think of the dog robot toy as an example of the level of resolution that is needed! Designing a robot toy alone is challenging so this is a lot to design, refine, and execute at a high level.

So, how might one think about making the jump to a realistic product design? My impression of the value proposition is to offer an exploration experience from a unique viewpoint. How do you focus on that core proposition and simplify the toy? Is it a high resolution, wearable viewer with a camera on a stick or your shoe that you can move? With the binoculars on, one can't see the robot anyhow. This approach allows you to focus on a good viewer toy, eliminates the driving controls and reduces the camera carrier design scope. Is it a cool robot that you can drive through different terrains and watch on a stable, quality video feed to any device one might own? In this scenario the design of the viewer is minimized. What is central to the exploration toy value proposition, and where is it unique and most competitive? I really encourage focusing on the aspect that most clearly delivers on that, and execute it at a high level. A simpler, focused proposition done well is better than many partially resolved sub-systems.

I would be happy to discuss design details in person with you as well.

Purple: Stall door opener
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Lots of pieces came together, so you were successful in creating a prototype that will help you target and refine the overall product design as a system. That is a good thing!

With automated devices, especially ones involving privacy, understanding its status is a good thing.

Also, there seemed to be very good overall team knowledge about what your product is and how it worked.

Some other thoughts and suggestions are below.

  • the opener drive seemed quite nice and quiet!
  • with automated devices, especially ones involving privacy, understanding the device's status helps people understand what is going on. It seems like status about being on, locking/locked, unlocking/unlocked and opening/open would be helpful. Battery life indicator?
  • it might be worth considering a solenoid to engage/disengage the latch. The solenoid would only be used to move the latch from one position to the other, and would be powered only momentarily.
  • the gesture sensor on the inside was quite close to the door, so it seemed like one would touch the door to wave over the sensors. Will items hanging on the door be an issue?
  • The integration of the sensors on the outside of the door can be refined. Does one need to cut holes for the sensors in the door? Could it be a thin surface mount array?
  • Are there ways that bad actors could trick the device into locking empty stalls?
  • if there are instruction graphics, they probably would be best on the device itself rather than on the door. The dot on the outside created some confusion about where to interact with the device, and the graphic on the inside seemed a bit out of place.
  • when designing the product enclosure, try to make sure the device does not afford collecting dirt, being gripped to pull off, or being used as a shelf.

Silver: tightening brace
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You have a clear and focused product value proposition, which puts you in a good position to develop a refined realistic product. Since it seems like braces are going to be quite variable in shape, size, and strap position, for me the trick seems to be how to design an elegant system/module that the brace fabricator can use to conveniently and quickly configure and install the tightening system. The new name is nice.

I imagine something like a "lego-like" semi-rigid base that can be trimmed to the needed shape and allows for the easy attachment of actuators, straps, etc. in appropriate locations would work well. This base with attached modules could then be attached to the brace, either with a few fasteners or perhaps a sheet of Velcro.

A few other comments are:

  • the hose clamp mechanism seems like it could be fairly low cost and compact.
  • even though the user cannot sleep on their stomach, it seems like something that is smooth and reasonably flat would be more comfortable, just for positioning bed sheets and moving your arms in your sleep, etc. Sharp corners or catch points seem like something to avoid.
  • think about status indication. It would be useful to show battery life and whether the device has tightened to the desired location/is working OK. Would it make sense to have a test mode to use each time before you go to sleep? That would allow the user to ensure that there are no problems before they are unconscious.
  • is it pressure that you really want to control? and is position a proxy for that? Just want to have the rationale and approach clearly understood and communicated.


Pink: Spotlight
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A lot of pieces have been worked on and you have made progress, but there is also a distance to go before achieving the performance that you require. And once you have that, you will need to work on detailing the design of the product.

Be sure to learn as much from the current prototype as you can. Some aspects of the prototype seemed a bit found object (main bearing, steppers) rather than what you would ideally source based on the design needs. Now is the time to do it for real, both in design detail and fabrication.

Some additional notes follow:

  • The system is several products in one. The transmitters, the device worn by the user, the light system, and the software. All deserve and need refined attention, detailing, and prototyping at refined, product-like level—and that's a lot of things! Maybe focus on designing the unique aspects of your product, and as much as possible building off appropriate sourced parts for the elements that are commodity. You are already doing this for the light. Can you do this for the gimbal? Are there off-the shelf gimbals to which you can attach actuators (I think yes), or if not can you lookup a standard gimbal design and implement that?
  • the prototype illustrates the importance of stiffness in the system, and that it needs to be quite damped. Happy to discuss design options with you in detail, but trying to build off a commercial gimbal design could be a real help.
  • as you know, the bandwidth of the control system was too low. But, even when baby stepping to move very slowly, the prototype illustrates that a bang-bang type control approach will be too jumpy, and exacerbate stiffness and vibration issues. I would think that a proportional control system (gain proportional to error size) would work fine.


Average reviewer score
The average reviewer score is on a scale of 0-10, where 10 is highest. The score is based on prototype operation and the assessment viewpoints outlined in the technical review description. The data are averaged from rankings provided by 45 reviewers.