Archive for the 'Initial Writeups' Category
Initial Writeup Assignment

Write an initial writeup for your prototypes.

  • due midnight before September 18

Find all the details in the template for the assignment

Team 9 – LED Zeppelin – Prototype I: Remote Piano Pedal Control

 

Concept Test

 

Picture/Image

Pictures show the flexibility and easy installation of the controller.

A cam operates by smoothly moving between up and down positions. The cam never leaves the surface of the pedal so noise is minimized 

Description

The Remote Piano Pedal Controller regulates the movment of two piano pedals in a natural way without having to retrofit or change the action of the piano in any way. This is accomplished through the use of a two axis controller, an interface, and a servo motor with a specially designed cam. There is some degree of flexibility in the choice of controller, based on the users specific needs. The options include: accelerometer, air controller, sono or laser motion detector, etc. The interface will be a programmable microcontroller. This will allow parameters to be set by the user based on user movement, pedal stiffness, desired response, etc.

Interview Questions

What is most convenient form of control for you? ie. Arm or leg movement, head movent, bite wing control, sip and puff control etc.  Are there any specific demands that need to be worked around? ie. Do you need to be able to talk or sing? Would a head movement controller be to distracting? Would a breath controller cause you to hyperventilate?

Description of Prototype:

The Remote Piano Pedal Controller regulates the movment of two piano pedals in a natural way without having to retrofit or change the action of the piano in any way. This is accomplished through the use of a two axis controller, an interface, and a servo motor with a specially designed cam. There is some degree of flexibility in the choice of controller, based on the users specific needs. The options include: accelerometer, air controller, sono or laser motion detector, etc. The interface will be a programmable microcontroller. This will allow parameters to be set by the user based on user movement, pedal stiffness, desired response, etc.

Testing:

     will reveal any latency issues with a wireless accelerometer and if that is a major factor in its use.

   will make the programmable parameters user friendly.

   Other unknowns include the range of piano pedal stiffness; how much force is required to depress a variety a pedals.

   The choice of  material for the cam must make it operate quietly and quickly and efficiently.

  The size and type of motor needs to be determined. It must move forward and backward quickly and smoothly to its (infinite number of) positions. (Not an on off switch)

Timeline:

The below table is just an example for how you might do a timeline. Content in the table is also just example content. Feel free to change and restructure the below table as you wish:

date process and goals comments
Sep 25
  • all components are in. Start initial playing with components, figuring out how they work.
  • continue experimental programming learning to use Arduino microcontroller
  • complete interviews with target consumers/consumer groups
 
Oct 2
  • initial Arduino programming complete
  • skeletal structure complete
 
Oct 9
  • hardware and software working together, although perhaps not robust yet
 
Oct 23
  • prototype completed, working, report submitted
 

Materials Needed:

qty item with link unit cost comments
1 variable postion motor   May have one available
1 arduino uno 30 any Arduino OK, including older Arduinos
2 Cam ? not yet secified, may be off the shelf or custom made, ?teflon or felt covered
1 Controller, ?accelerometer   Two axis controller would allow control of two pedals
1 accelerometer receiver   for wireless version, project might end up being wired ?latency
       
       
       
       
       
MARZ – Prototype I: Campus App

Concept Test

Picture/Image

Description

We are working to develop an interactive smartphone app/website for college campuses. This app provides ways for any college student to network on their campus as well as assisting them in finding specific information regarding any groups, activities, events, and classes that they may need.

The app contains an interface comprised of layers that the user can choose to enable that displays different topics. One layer is the “Campus” layer, which displays a map of their campus and the surrounding buildings on campus. The app would be GPS-enabled, allowing the user to see exactly where they are in relation to the class that they are about to be late for. Another layer, the “Groups” layer, superimposes on top of the Campus layer and displays icons on the tops of buildings that show where these student groups meet. The user can double-tap on any of these icons to find out more about these groups, such as meeting times, contact information for the group leader, upcoming events within the group, or other group announcements. The “Classifieds” layer provides a way for students to post information about books they would like to sell, roommates they need, or furniture that needs a new home. (The current way to do this is to post flyers on the boards throughout the buildings on campus, which are only seen by a small percentage of the student population. Anyone can just get on the app and scroll through a sectioned list of classifieds find what they are looking for.) This app will allow for scalibility by allowing schools to create their own layers. For instance WSU students could use a “Construction Detours” layer to avoid the mess surrounding RSC and plot the quickest route to their destination.

The hardware portion of this idea consists of outside modules (similar to the ones at the zoo) that activate when the user goes near them with the app open. The user presses a button on the app, which will then begin “talking” to the user, giving the them a description and history of the building, artwork, statue, or other landmark on campus. This would be great for orientation leaders who spend all day trekking across campus with new students, and would provide an excellent means to display outdoor sculptures. Any time they forget information about something or just need to take a break, they could activate a module let the app talk for them! New students that do not want a campus tour can use this app to help them navigate the campus. A website for all this would be available as well. The website is referenced by the app, but could also be used directly if users are unable to use the app. We will create a web server to give the app a database and functionality.

We think that this is a great idea that could be implemented on almost any campus worldwide. The modules would be programmable and the layers could all be modified by an administrator so that each campus could choose what layers they want to implement. A few years back, WSU attempted to create a networking website for students. As a website, it did not catch on because there were few activities listed and very little interaction was provided. It was not well publicized and just did not get enough users. We feel that with the proper showcasing and development, this app could be a hit not only for new students, but for faculty, staff, parents, and graduates alike.

Interview Questions

  1. Do you know of any social network / website that is used by your campus to promote the activities available on campus as well as a guide on how to navigate the campus?
  2. If so, have you used this app / website before or have at least visited the app / website?
  3. Would you be interested in learning more about all there is available on your campus as far as student groups to join, activities promoted by these groups, or events hosted by campus (including sporting events and social events)?
  4. Would you be willing to pay an amount of money to have access to this app / website (which would be constantly updated whenever new information was available)?
  5. If you are a leader / founder of a student group, would you be interested in being able to post your group’s information / events on the website so that others can see this information and be able to contact you with any questions?

Other questions for non-students (faculty, admin) may include:

  1. What kind of interest do you think this app would generate on your campus?
  2. What methods are currently used to tell students about events on campus?
  3. Do you think that student involvement would increase with the addition of this app on your campus?
  4. Do you feel as though a majority of the students on campus know much about the university itself (history, art, iconic locations)?
  5. Do you think that students, potential students, and maybe even faculty would benefit from using the on-campus modules?

Description of Prototype:

Our system will likely need to be considered in stages. Approaching the prototypes with a modular design will allow us to add some of the non-core features later on. Fortunately, our project lends itself to this modularity.

The core part of the Campus App lies within the setup of a web server, as well as designing the mobile apps in software. Our first should be an Android application with the Campus App GUI. The GUI needs to be a threaded android (java) application which listens to and communicates with the web server for updates. Threaded retrieval of fine GPS coordinates should integrate into our map. We need to test that we can push info and serve requests from the web server’s application code. We need to construct GUI’s based on dynamic server requests. All of this will allow us to establish the feasibility of the campus app.

With the core engine of the app and server mostly in place, we could begin to implement some of the other features mentioned for our second prototype, and to refine and add “perk” features for our final prototype. A database for registering users of our application might allow for interesting integration with social media. Then users can post classifieds, look for school events, and other postings. All of these things should rely heavily on a dynamic GUI engine to decode our server requests. Meticulously preparing the engine code for dynamic use will be crucial to a smoothly working prototype.

Timeline:

We will need to develop at a fairly quick pace to meet these deadlines, but we believe the following schedule is achievable:

Date Goals Notes
2012-09-25
  • Set up server and necessary services
  • Research Google Maps API for Android
  • Develop server and client proto-code
  • Set up development environment for all group members
We could use a group member’s server or request funds for an offsite server. The second option will likely be cheaper and faster.
2012-10-02
  • Server up and able to respond to queries
  • App is working and able to send/receive basic query information
At this point, we’re just looking for basic network communication between the Android application and the server backend.
2012-10-09
  • Server able to respond to location-specific queries
  • App able to display user’s current location
  • Prototype I Final Report
The goal of our first prototype should be realized at this point.

Materials Needed

Fortunately, our project requires very few physical resources.

Item Cost Comments
Web Server $0-$30 per month We’ll need to research what servers are available with the features we need.
Android Phones $0 Three group members have phones for testing; emulation is also available.
Team Alpha – Prototype I: TrueView Power Chair Camera System

 

YouTube Preview Image

Description

The TrueView camera system will allow those with limited mobility to take full precise control of their power chair. The TrueView system will include a panoramic wide view rear back lens camera that will allow the user to see any obstacle behind them in clear real time fashion. The TrueView system will have the ability to be fully customized to all makes and models of power chairs and it will be fully modular for future hardware and software upgrades. The user will have the option to upgrade the system to have fully automated 360 degree viewing capability if needed. There will be options for multiple front and rear mount cameras and even under carriage mount to overcome any and every obstacle that one may come across. All of this viewing power will also be controlled by a convenient and powerful dedicated touch screen device that will allow multiple or single views that can be changed with a simple swipe gesture. There will also be options in the future for night viewing and obstacle alert sensors. The TrueView system will be the most powerful and comprehensive camera system for power chairs on the market.

Interview Questions

1. How often do you find yourself needing more viewing capability behind your power chair? On a daily basis? Or just occasionally?

2. Do you have viewing challenges unique to your model of power chair? Does your model allow enough mobility to see to the peripheral areas of your surroundings?

3. Do you travel or have the need to travel on your power chair at night? If so, do you find obstacles to be more prevalent at night whether at home or outside?

4. What is your comfort level with touchscreen devices? What models, if any, of tablets have you used? Are you familiar with Android or IPad operating systems?

5. Do you ever have issues with obstacles above or below your power chair device? For example, have you ever had issues with bumps or cracks that would require better viewing underneath the power chair? Has there been any issue with vertical clearance of your power chair? Does it sit too high to avoid certain obstacles.

Description of Prototype:

The bare minimum criteria for our design is the rear viewing capabilities according to our research. The residents stated that this is a frustrating aspect of their power chairs in that they cannot see behind them and that it has caused accidents and damage to property and the chairs themselves. I feel that this will be the very first and most crucial point that we will demonstrate with this design.

I feel that we will need to focus on the quality of viewing behind the chair and the ease of use of the interface to view and interact with that rear view camera. Our first prototype should include one camera and one interface device that can control the power and viewing of the camera. We will then also demonstrate a simple but effective software system that the user will be able to confidently control the system with. This basis of hardware and software working in unity will open up the possibilities to a large number of upgrades and customization that may be done at the request of the customer. We may also then fully explore a more robust multi-camera system and even the possibility of different lens that will allow night viewing for future upgrades due to customer demand.

Timeline:

date process and goals comments
Sep 25
  • Start Working on prototype I 
  • We will get all the components together and start building
  • Get the data from the Cerebral Palsy residence 
 
Oct 9
  • Hardware and software needs to be done
  • We will have both the software and hardware running but it doesn’t have to be running together
 
Oct 23
  • Hardware and software will be done
  • We will have the prototype done and we will be done with the report
 

Materials Needed:

This section is extremely important as it serves as an order form for John. Include in this section the email contact of who on your team is solid on their knowledge of what is needed and will be quick to respond to emails John sends; John may have to go back and forth with this person via email a few times to help nail down what should be ordered given the various constraints of the project and the class itself.

John is really happy to help you with this section. Just email him and come during his office hours (Tuesdays at 11 and Wednesdays at 9) to nail down what you need and where to get it.

Please include links for every item so John can get a clear idea of what you need. Content in the table is also just example content. Please change for your needs:

qty item with link unit cost comments
1 Arduino 30 any Arduino OK, including older Arduinos
1 Touch Screen Tablet  67 Pandigital 7″ or similar with Android Operating System
1 Web Camera 30

Logitech commercial off the shelf model or similar.

1 Raspberry Pi 35

Raspberry Pi computer with Linux OS

Group 5- Personal In-Home Rescue Lifter A.k.a The PIRL5000

Personal In-Home Rescue Lifter [PIRL5000]

Description

Features: 

  • Push-to-help button sends signal to rescue robot and will come to your location
  • Electronic Guidance System
  • The person will maneuver them self into the straps
  • There will be very long metal tubing in the center of the lifter with a cable inside
  • Harness will be connected to the end of the cable
  • After you buckled up, rescue lift robot will help you get up
  • Once the robot has completed its task, it will be sent home
  • Rescue Lift Robot will charge itself, once it has reached the charging station

Benefits:

  • No 500 dollar fee to have EMS come to your door if you can’t get up
  • You will be able to pick yourself up without anyone’s help
  • Convenient and quicker way to get off the floor
  • More independence and freedom living at home

Interview Questions

 

  1. How many times do you fall in a month?
  2. Where the place in your house where fall the most?
  3. How long do you have to wait for the rescue team/someone to help you get up?
  4. What do you think about the Robot Rescue Lifter?
  5. Where would be the most convenient place to put the Robot Rescue Lifter Station?
  6. Are you able to maneuver your arms into a harness/strap if it is by your side?
  7. Can you assist the Rescue Lifter Robot by pushing your legs up during the last stage of the process?
  8. Do you have any hallways or doorways in your house that are less then 3ft wide?

 

Description of Prototype:

For our Prototype I we would like to build the base of the Robot and lock the wheels into the frame of the Robot so it can sit on a flat service. We would like to begin by programming a device that controls the Robots direction of travel. 

 

Rough Draft Image

 

Timeline:

 

date

process and goals

comments

Sep 25

  • All components are in. Begin with small prototype, to demonstrate how guidance system works. Start figuring out how the components work.
  • Continue experimental programming learning to use Arduino microcontroller
  • Complete interviews with target consumers/consumer groups

 

Oct 2

  • Initial Arduino programming complete
  • Basics of the Robot Complete the frame, the wheels, the motor, and the Robot is capable of moving

 

Oct 9

  • Navigation System working, hardware and software working together, few bugs in the system

 

Oct 23

  • Prototype completed, and working, report submitted

 

 

Materials Needed:

 

qty

item with link

unit cost

comments

1

R/C Car

29.41

To work on our navigation/guidance system

1

Arduino

0.00

Any Arduino works

3

Distance Sensor

13.99

Senses when it has reached a wall

1

Line Tracking Kit

39.99

Follows a black line on a white floor

       
 6  Total  111.37  

 

Group 3 – Prototype I: Rolleover Protection Arms

Concept Test

Picture/Image

Description

This product will be built into existing wheelchairs.  There will be three arms that are free swinging attached to the wheelchair.  Level sensors will detect when the wheelchair is unbalanced and about to tip right, left, or back (optional).  This will make a motor activate that will hold the arm in place and then correct the position of the wheelchair before it falls.  

This will benefit people in wheelchairs because they will not need to wait for assistance if their wheelchair is going to tip over.

Interview Questions

1. How often do you need assistance  with this?

2. In what kind of places do you need this assistance?

3. How much would you be willing to spend on this product?

4. Do you think this will help people?

5. What can be added to improve this product?

Description of Prototype:

The prototype will consist of the arms for stabilizing the wheelchair.   The arms will incorporate a hydraulic system controlled by an electrical system with sensors for the  level of the chair.  The system will be powered by the wheelchair’s existing battery. 

Timeline:

date process and goals comments
Sep 25
  • Start initial playing with electrical components, figuring out how they work.
  • Finish model drawings and calculations.
  • continue experimental programming learning to use Arduino microcontroller
  • complete interviews with CPRF residents
 
Oct 2
  • initial Arduino programming complete
  • design of skeletal structure complete
  • start on hydraulic system
 
Oct 9
  • hardware and software working together, although perhaps not robust yet
 
Oct 23
  • prototype completed, working, report submitted
 

Materials Needed:

qty item with link unit cost comments
2 hydraulic cylinder  $80  
1 arduino uno 0  
1 hydraulic pump  $150  
1

Triple Axis Accelerometer 

 $14.95  
       
       
       
       
       
       
Out of Time – Prototype I: Peltier cooling unit

 Concept Test

 Picture/Image

Description

The concept test will be a electronically assisted cooling and heating device which can sustain long periods of use. This will be accomplished by using Peltier cooling units with heat syncs to circulate the thermal energy throughout the desired area.

Interview Questions

  • Do you think this is a decent idea?
  • What benefits would come out of this?
  • How can we improve the idea?
  • Would you buy this?
  • Are there any specific needs or requirements for this we might need to adjust for?

Description of Prototype:

We plan to make a small cooling unit using the peltier coolers. We will then make a circulation system and test to see the efficiency of the current coolers. We will then adjust to achieve maximum efficiency.

 

Timeline:

All times will depend on availability of needed materials.

date process and goals comments
Sep 25
  • all components are in. Start initial playing with components, figuring out how they work.
  • complete interviews with target consumers/consumer groups
 
Oct 2
  • structure complete
 
Oct 9
  • hardware and software working together, although perhaps not robust yet
 
Oct 23
  • prototype completed, working, report submitted
 

Materials Needed:

 

qty item with link unit cost comments
8 peltier coolers asst. 100 Might need multiple sizes
3 arduino uno 30 each any Arduino ok, would like multiple for each member to do own testing.
1 heatsink 15 going to depend on size of actual cooler
1 computer water pump 20 to circulate cooled water
1 power supply 10-20 use arduino to control
Team 12: Home Automation Framework – Initial Write Up

Home Automation Framework


Description of Idea

Our intent is to develop a web application that can remotely control the electronic devices in one’s home via mobile interfaces such as smartphones & tablets, or any OS with a web browser. The underlying technology will likely utilize an Arduino and a small, low-powered web server such as the Raspberry Pi.

Example systems that we may monitor or control:

 

  • Technology & Entertainment:
    • TVs
    • Radio/CD/MP3 Player
    • Computer
  • Energy-Saving:
    • Lights
    • Ceiling fans
    • Thermostats
  • Appliances
    • Washing machines
    • Stoves
    • Refrigerators
  • Security Tools & Devices
    • Security cameras
    • Electric door latches
    • Electric window blinds


Goal: Facilitate ease of access & control of electronic devices for those who are busy, have a disability, or are not physically present in the location of the device.

Potential features for expansion:

  • Bluetooth technology
  • Compatibility with existing home automation products such as X10
  • API that is accessible to the casual DIY hobbyist.
    (This would make it easy to integrate with existing home automation systems, to make them available through a web interface.)
  • Monitor electricity use
  • One-touch security or power-saving features (e.g., “lock all doors” or “all off”)


Interview Questions
CPRF Interview Questions

  • If you could control things with mobile phone or through the internet what devices, appliances, locks, lights, etc. would you like to see become automated in your home?
  • How do you typically access the internet (PC, Tablet, Smartphone)? Do you have texting service on your mobile phone?
  • How often do you access the internet?
  • Would you rather be able to use your automated appliances, etc. (longer range) via the internet or with an RFID keychain (super close range)?
  • Would you be willing to buy an in-house server and boxes to automate your appliances/locks/etc in order to have this convenience? If so, how much would you be willing to pay for this service? Would you rather pay a large one time fee for the equipment and setup, or would you rather pay a monthly fee for the service?

Description of Prototype
This product will consist of 3 elements:

 

  • Server: Low-cost home server (possibly Raspberry Pi). It will have some sort of wireless controller to communicate with the actuator.


  • Client: Mobile Friendly application. The actual protocol hasn’t been determined yet. It will communicate with the Server to tell it which devices to turn on, off, or other function.
  • Actuator: Simple device with wireless connectivity, within range of the server. It will interface with power outlets and appliances. To the command of the server, it will turn it on or off.

Initial prototype:

  • The initial prototype will be the web server, with at least one of the I/O devices to output orders to an Actuator. While the Actuator will not be finished yet, we should still have some way of confirming the order was sent and can be received from a maximum range of device.


Timeline

Date Process & Goals Comments
Sep 25 All components are in. Start initial playing with components, figuring out how they work;
continue experimental programming learning to use Raspberry Pi server;
complete interviews with target consumers/consumer groups.
 
Oct 2 Initial Raspberry Pi server programming complete;
skeletal structure complete.
 
Oct 9 Hardware and software working together, although perhaps not robust yet.  
Oct 23 Prototype completed, working, report submitted.  

 

Materials Needed

Qty Price Item Description
1 $35 Raspberry Pi board
1 $0 Resistors (assorted) (should be in design lab already)
1 $0 Transistors (assorted) (should be in design lab already)
1 $0 LEDs (for testing) (should be in design lab already)
1 $0 Breadboard (should be in design lab already)
1 $0 Arduino (should be in design lab already)
1 $20 RF-controlled power sockets (on Amazon)
7. Team Bravo Squad – Prototype I: Emergency GPS Locator

 

Concept Test

Picture/Image

Description

This device will attach to your motorized wheelchair’s battery and monitor the amount of charge left. When it detects that the battery is critically low, it will automatically broadcast your geographical location to a pre-determined emergency contact, notifying them that you need assistance. For any other kinds of emergencies, there will be a manual switch that broadcasts your location to the emergency contact, in case you are in need of assistance and do not have any kind of cell phone. The device will be designed to run on low power, and recharge automatically with your chair; and its functions will be kept simple so that it requires little to no maintenance, putting emphasis on reliability when needed.

Interview Questions

What questions do you need to ask potential customers to garner their perspective regarding the product and its benefits and features.

Description of Prototype:

Our first prototype will be focused on interfacing an Arduino with a GPS module correctly, and being able to successfully parse the data returned by the module. It will be testing the location component of our project. The basic premise is that on a signal (mimicking the pressing of the emergency switch) the GPS module will be powered on and the location (latitude and longitude) will be polled successfully.

Timeline:

date process and goals comments
Sep 25
  • all components are in. Start initial playing with components, figuring out how they work.
  • continue experimental programming learning to use Arduino microcontroller
  • complete interviews with target consumers/consumer groups
 
Oct 2
  • initial Arduino programming complete
  • skeletal structure complete
 
Oct 9
  • hardware and software working together, although perhaps not robust yet
 
Oct 23
  • prototype completed, working, report submitted
 

Materials Needed:

This section is extremely important as it serves as an order form for John. Include in this section the email contact of who on your team is solid on their knowledge of what is needed and will be quick to respond to emails John sends; John may have to go back and forth with this person via email a few times to help nail down what should be ordered given the various constraints of the project and the class itself.

John is really happy to help you with this section. Just email him and come during his office hours (Tuesdays at 11 and Wednesdays at 9) to nail down what you need and where to get it.

Please include links for every item so John can get a clear idea of what you need. Content in the table is also just example content. Please change for your needs:

qty item with link unit cost comments
1 GPS module 50 any Arduino GPS module ok
1 Arduino 30 any Arduino OK, including older Arduinos
1 GPS antenna 10 any GPS antenna ok
Infinite Loop – Prototype I: Hazardous Weather Warning System

 

Hazardous Weather Warning System

 

Purpose:

                To help inform the residents of the Cerebral Palsy Research Foundation (CPRF) when dangerous weather conditions are imminent and appropriate precautions should be taken.

Overview:

                “The Timbers has (3) above ground tornado shelters, each is a free standing structure and visible throughout certain parts of campus. When a tornado watch is issued a post call is sent to each resident (automated call with a recorded message detailing date/time/duration of the watch) and the shelters are unlocked in the event that severe weather might materialize. In the past there has been talk about having a light system attached to each shelter; mounted high enough to be seen and vivid enough in color to be visible day or night. A certain color would designate a watch and another color would designate the all clear.” Our group is proposing to implement a system like the one detailed above.

Layout:

                As described about there will be an indicator attached to the top of each tornado shelter, for a total of three. Each indicator will be made up of two high intensity lights, one red for weather hazard and one green for all clear. These lights will be run by a digital wireless system that will in turn be controlled from the ground by a single unit. The ground unit will contain both local and remote control systems, allowing more flexibility.

Product Stages:

            Proof of concept (Prototype 1):

                                A small scale system will be implemented, using simple LEDs, wireless controllers and only a switch on the controller unit to illustrate that this system is viable.

            Prototype 2:

                                The main controller will be upgraded to add remote control capabilities as well as upgrading the wireless transmitters to devices that would be powerful enough to be used in the final product and testing them on location to verify the feasibility of the system.

            Final Product:

                                The finishing touches will be made to master control , high intensity lights are added to the system, weatherproofing is added to the system, final product is installed on location at CPRF.

Possible Feature additions:

  • A system that taps into NOAA weather streams to automatically activate the system
  • A cell phone app control
  • Website control

 

date process and goals comments
Sep 25
  • Complete interviews and see if this project is even desirable
 
Oct 9
  • Obtain all materials needed and get set up to run the project
 
Oct 16
  • Have the prototype mostly finished and in a rough test mode..
  • If possible, attempt to mesh the 2 methods into one item
 
Oct 23
  • Have prototype
 

Materials Needed: (Will be changed pending discussion with CPRF)

Jeffrey Stoss: stossj@gmail.com

 Please change for your needs:

qty item with link unit cost comments