Exercise 4 - 02/27/2018

Designing Each Task in a Problem-Solving Effort

Device Goals & Specifications

• Qualitative constraints
  1. Safety
     • Shall not impede the User’s safety. This process cannot be more uncomfortable than using a traditional mouse.
  2. Environmental protection
     • Shall not use materials that hurt the environment. Do not use carcinogenic or toxic materials in the fabrication of the device.
  3. Public Acceptance
     • People may be skeptical about the performance and benefits of using this device over a traditional mouse. The consumers need to understand and trust the benefit of using this product.
  4. Reliability
     • Shall reduce tracking false movement, ensuring a reliable and error free tracking in multiple scenarios.
  5. Performance
     • Shall have no significant reduction in throughput using the device instead of a mouse.
     • Shall have an 8-10 hour battery life.
  6. Ease of operation or operating conditions
     • Shall have an intuitive design that makes it easy to operate even for the first-time user. Also, device shall be easy to use by the elderly as well as people with disabilities like arthritis and Parkinson's disease.
  7. Durability
     • From work and home use, the estimated time a person uses the computer is 8 hours a day. Therefore, device shall be able to withstand everyday use.
  8. Use of standard parts
     • Device shall be made with common and cheap parts. By using cost effective components, the device will remain affordable for the consumer.
  9. Minimum Cost
     • As mentioned before, using cheap parts will make the product affordable. Also, the price for this device shall be competitive with regular mice as well as alternatives that are used by people with disabilities.
  10. Maintenance
      • The product shall require no maintenance to upkeep.
• Quantitative constraints
  1. Data collected will have the capability to be used to extract meaningful vector motion results in real-time.
  2. Motion data shall be smoothed using error correction in order to extrapolate desired movement from inaccurate input.
  3. The time lapse between input and pointer movement shall be within a time margin that is unnoticeable to the user. The input latency for a wired USB Logitech gaming mouse, the G900, has on average a 4.5ms, a SteelSeries Rival averages 7.5ms, and the DeathAdder Chroma averages 11ms input delay (Source: PC Gamer).

Functional Goals & Specification

• Tracking:
  1. Tracking
     • Shall operate like a normal mouse from the software side.
  2. Durability
     • Device shall be built in a rigid form factor.
     • Depending on the final solution, if a wristband is used to track motion, we shall make the wristband with a comfortable and durable material.
  3. Ergonomic
     • Device shall not require the user to grip anything.
     • Hand will be in a relaxed position to minimize pain and discomfort.
     • The user will be able to use for extensive periods of time.
  4. Ease of Operation
     • Tracking shall be accurate and account for sudden hand motion.
     • Tracking shall only be in a 2-D space.
  5. Reliability
     • Device shall reduce tracking false movement ensuring a reliable and error free tracking in multiple scenarios.
• Clicking
  1. All clicking functionality shall be accounted for and mapped to a gesture in 3-D space or an easy-to-use additional movement: Single Click, Double Click, Right Click, and Scroll.
  2. Ergonomic
     • Device shall have limited additional hardware for the Clicking functionality.
     • The user shall be able to perform clicking functions with comfort.
  3. Ease of Operation
     • Clicking motions shall not require complex or restrictive motion.
     • Clicking could leverage 3-D space in such a way as to not impede tracking.
  4. Reliability
     • Device shall consistently recognize clicking functions without false positives.
  5. Performance
     • Clicking functionality shall come close to the same time frame as a traditional mouse, within a reasonable margin of error.
  6. Durability
     • Clicking function shall not provide significant additional wear to device.
     • Clicking functionality shall not put an unreasonable strain on battery life.

Eliminating Paths

Our first design solution is to implement a camera for motion tracking of the users hand.

1. We chose to consider this option because:
   • Simplicity involved in implementation (mainly a software solution).
   • Motion tracking has a low cost of implementation.
   • A higher level of accuracy.
2. We choose to eliminate this option because:
   • An additional camera hardware with tracking software would be required.
   • Software would have to identify different skin tones, and hand shapes.
   • May impede ease-of-use requirements.

Our second design solution would be to implement a bracelet to track the orientation and movement of users’ hands using accelerometer/gyro or other sensors.

1. We chose to consider this option because:
   • It presents a learning opportunity of working with Bluetooth and new sensors.
2. We decided not to eliminate the bracelet as an option. The bracelet would fulfill our design requirement, but there are a few critical points in our design constraints that could create issues in the design process. Below we describe some of the constraints we need to actively consider if we choose to pursue this option.
   • Using a bracelet would communicate wirelessly with a receiver. The bracelet would require a battery to operate. Making sure the battery is not to large and the power draw is minimal is critical point for guaranteeing the device is small and operates for a long enough period of time.
   • If a bracelet requires inertial data, the amount of movement that is required to register as a movement or a click would be dependent on the user passing a movement threshold. The threshold would be required to account for the possible error in movement.
   • Clicking functionality shall be able to be performed within the same time frame as a traditional mouse, within a reasonable margin of error.

Our third design solution would be to use fixed-point rf-triangulation.

1. We chose to consider this option because:
   • RF triangulation accuracy can be tuned based on the frequency in use.
   • Methods exist for object triangulation with RF.
   • RF-Triangulation sounds cool.
2. We chose to eliminate this option due to these factors:
   • Would require millimeter-band Tx/Rx, which would be cost ineffective and too bulky to be practical.
   • RF is subject to noise, decreasing reliability.
   • Would require digital signal processing, which would increase latency and cost.