Fall 2016 Prosthetic Hand: Requirements Evaluation

Fall 2016 Prosthetic Hand – Requirements Reevaluation

Project Manager – Kimberly Younger

Mission, Systems, and Test Engineer – Mia Lai

Table of Contents

Evaluation Summary

By Project Manager – Kimberly Younger

According to the Nasa Requirements Appendix C [1], requirements should use a positive active tense. In addition, requirements should be composed of consistent terminology throughout. Requirements describe the ‘WHAT’ of the project rather than the ‘HOW’. Requirements should be clear and unambiguous while remaining concise and simple. Requirements should express one thought with subsequent, descriptive thoughts used as lower level requirements. Requirements are necessary for the functionality or mission of the system. They should align with the goals and objective of the project.

In order to better exemplify these qualities, the Prosthetic Hand group has updated our project, system, and subsystem requirements.

References

[1] NASA System Engineering Handbook – Requirements

http://web.csulb.edu/~hill/ee400d/Lectures/Week%2004%20Modeling/d_NASA%20Requirements.pdf

Original Requirements

By Project Manager – Kimberly Younger

By Mission, Systems, and Test Engineer – Mia Lai

By Electronics and Control Engineer – Sara Gonzalez

R1 – The Prosthetic Hand will be a functional component of the Prosthetic System by having capabilities to attach and work with the Prosthetic Arm.

R1.1 – The Prosthetic Hand shall connect to the Prosthetic Arm at the base of the wrist.
R1.1.1- The maximum weight of the prosthetic hand should not exceed 5 lbs. [1]
R1.2 – The Prosthetic Hand shall include rotation in the wrist.
R1.2.1- The wrist of the Prosthetic Hand shall have a diameter between 3-5 inches’ in order to meet size requirements dictated by the Prosthetic Arm group.

R2 – The Prosthetic Hand shall feed a person a McDonald’s Quarter Pounder with Cheese meal (as defined by the McDonald’s website [2]) within twenty minutes of first picking up the meal.

R2.1 – To accommodate the meal time, the battery that will be used shall last at least 20 minutes.

R3 – The Prosthetic Hand shall be capable of picking up a medium drink/malt, Quarter Pounder with Cheese, and bundles of French fries (1-10 fries per bundle) without breaking the cup/food item.

R3.1 – The grasping speed of the hall shall be between 115 degrees per second and 250 degrees per second. Grasping speed is defined by the speed of the hand from an opened position to a closed position. This speed was suggested as most practical by Joseph Belter of the GRAB lab at Yale University [3].
R3.1.1 – The grasping speed will be controlled via a motor driver connected to an Arduino Uno and Arduino IDE software, as demonstrated by the TACT Hand. [4]
R3.2 – There shall be preprogrammed grasping patterns for the hand, including cylindrical grasp, rectangular grasp, and a pinch grasp.
R3.2.1 – The cylindrical grasp shall pick up 500-700 grams of liquid, as is standard soft drink mass for a 21-ounce cup. [2]
R3.2.2 – The rectangular grasp shall pick up 160-180 grams of burger, as is standard Quarter Pounder with Cheese size. [2]
R3.2.3 – The pinch grasp shall pick up 2-30 grams of fries at a time, as it is standard for one French fry to weigh 2 grams. [2]
R3.3- The average force of the grip on an object shall not exceed 5 Newtons [4].
R3.3.1 – The pressure applied by the prosthetic fingers on each food object shall have a force accuracy range between 5% to 25% of the ideal, in order to accommodate the margin of error of force sensitive resistors. [5]

R4 – The Prosthetic Hand movements shall not be controlled by the other hand.

R4.1 – The prosthetic hand shall have an input device that allows the users to use their feet to control the unit.
R.4.1.1 – The external controller shall connect and control the prosthetic hand wirelessly, with a minimum range of 0 feet and a maximum range of 200 feet, in order to remain in the communication range of the Bluetooth mechanism of the hand. [6]

R5 – The total cost of the project shall not exceed 400 USD.

R6 – The project shall be completed on or before the end of the CSULB Fall 2016 Semester, which is 12/22/2016, as defined by the CSULB Academic Calendar. [7]

Original Requirements References

[1] Mass Requirements

https://www.arduino.cc/en/Main/ArduinoBoardUno

https://www.sparkfun.com/products/13197

https://www.pololu.com/product/1182

http://rogerparks.com/instructional/escap-16-gear-motor-encoder/

http://www.servodatabase.com/servo/towerpro/sg90

https://www.adafruit.com/products/166

http://www.digikey.com/product-detail/en/ROB-09238/1568-1105-ND/5318747?WT.mc_id=IQ_7595_G_pla5318747&wt.srch=1&wt.medium=cpc&&gclid=CJme97nWn88CFURffgodn6gHzQ

[2] McDonald’s Quarter Pounder with Cheese Meal

https://www.mcdonalds.com/us/en-us/about-our-food/nutrition-calculator.html

[3] Joseph Belter Grasping Speed

http://www.rehab.research.va.gov/jour/2013/505/page599.html

[4] Tact: Low Cost, advanced Prosthetic Hand

http://www.instructables.com/id/Tact-Low-cost-Advanced-Prosthetic-Hand/?ALLSTEPS

[5] FSR Integration Notes

https://cdn-learn.adafruit.com/assets/assets/000/010/126/original/fsrguide.pdf

[6] XBee Trace Antenna

https://www.sparkfun.com/products/11215

[7] CSULB Academic Calendar

http://web.csulb.edu/divisions/aa/calendars/

Requirements Evaluation Rubric

By Project Manager – Kimberly Younger

Is the requirement, Quantitative, Verifiable, and Realizable?
Is the requirement located at the correct level?
Is the requirement response to a higher level requirement or customer’s objective (Requirement Flow Down)? Is the linkage clearly defined?
Does requirement provide links to source material?
Does the requirement move the design process forward?
Are equations used to calculate a requirement provided and are answers correct
Is language in the form of a requirement?

Figure 1: Evaluation Rubric

In order to properly evaluation each requirement, this matrix was created that evaluates each requirement with the necessities of a requirement, as defined by the evaluation rubric above.

Updated Requirements

By Project Manager – Kimberly Younger

By Mission, Systems, and Test Engineer – Mia Lai

These requirements more accurately reflect the project of the Prosthetic Hand.

R1 – The Prosthetic Hand will be a functional component of the Prosthetic System by having capabilities to attach to and to work with the Prosthetic Arm. [1]

R1.1 – The Prosthetic Hand shall connect to the Prosthetic Arm at the base of the wrist.
R1.2 – The Prosthetic Hand shall include rotation in the wrist.
R1.2.1 – The Prosthetic Hand shall have the ability to rotate clockwise and counterclockwise at least ninety degrees from the neutral resting position. This shall be done to accommodate lack of rotation at the elbow. [2]
R1.2.2- The wrist of the Prosthetic Hand shall have a diameter between 75-125 mm in order to meet size requirements dictated by the Prosthetic Arm group.

R2 – The Prosthetic hand will be humanoid.

R2.1 – The mass of the entire hand, not including power sources or external input devices, should be between 350g and 1350g as suggested by Joseph Belter of the GRAB Lab at Yale University. [3][4][5][6][7][8][9][10]
R2.2 – The length of the prosthetic hand measured from the tip of the middle finger to the wrist should be between 170 mm and 250 mm, to emulate a human hand, as suggested by Joseph Belter of the GRAB Lab at Yale University. [3]
R2.3 – The width of the palm should be between 75 mm to 120 mm, to emulate a human hand, as suggested by Joseph Belter of the GRAB Lab at Yale University. [3]

R3 – The Prosthetic Hand shall feed a person a McDonald’s Quarter Pounder with Cheese meal (as defined by the McDonald’s website [11]) within twenty minutes of first picking up the meal.

R3.1 – To accommodate the meal time, the battery that will be used shall last at least 20 minutes.

R4 – The Prosthetic Hand shall be capable of picking up a medium drink/malt, Quarter Pounder with Cheese, and bundles of French fries (1-10 fries per bundle) without breaking the cup/food item.

R4.1 – There shall be preprogrammed grasping patterns for the hand.
R4.1.1 – There shall be a cylindrical grasp that shall pick up 500-700 grams of liquid, as is standard soft drink mass for a 21-ounce cup. [11]
R4.1.2 – There shall be a rectangular grasp that shall pick up 160-180 grams of burger, as is standard Quarter Pounder with Cheese. [11]
R4.1.3 – There shall be a pinch grasp that shall pick up 2-30 grams of fries at a time, as it is standard for one French fry to weigh 2 grams. [11]
R4.2- The force of the grasps shall range between 0.02 Newtons and 6.9 Newtons, as defined using Newton’s second law.
R.4.2.1- The force margin will lie between 5% to 25% in order to accommodate typical force sensitive resistors. [12]

R5 – The Prosthetic Hand movements shall be controlled without the use of another hand. [1]

R5.1 – The prosthetic hand shall have an input device that allows the users to use their feet to control the unit.
R5.1.1 – The external controller shall connect and control the prosthetic hand wirelessly, with a minimum range of 0 feet and a maximum range of 200 feet, in order to remain in the communication range of the Bluetooth mechanism of the hand. [13]

R6 – The total cost of the project shall not exceed 400 USD. [14]

R7 – The project shall be completed on or before the end of the CSULB Fall 2016 Semester, which is 12/22/2016, as defined by the CSULB Academic Calendar. [15]