Week 5 - Established Need and its parameters (FRSARC) (ref. Week 5 presentation)

Need 1: Automatic Bottle Opener

Problem Statement:

Opening a bottle can be difficult because it requires the user to grip the bottle with one hand and grip the cap with the other while applying sufficient torque.

Target Audience:

People with severe form of arthritis, upper arm amputations, arm/hand deformities, and the elderly

Functional Requirements: (ref. Common household bottles/jars spreadsheet on Drive)

• Able to accomodate bottle heights of 110mm - 310mm
• Able to grip bottle lid sizes of 20mm - 100mm
• Able to grip bottles with a diameter of 60mm - 140mm
• Apply 10 N-m of torque
• Able to open within 10 seconds
• Dimensions (LxWxH): 254mm x 254mm x 457mm
• Cost less than $50

Solutions:

Analysis/Feasibility:

• Our product has 3 overall movements: 1. Apply a torque to the lid of 10 N-m, 2. Grip the bottle to prevent it from rotating (counter-torque), 3. Apply the torque to the lid for all bottle heights.
• From this, we estimate that we’ll need a maximum of three motors to apply those movements. Applying 10 N-m of torque is feasible by using a gearbox to increase the output torque of the motor. For the gripping aspect, according to a journal of ergonomics, the average grip strength of a 20-29 year old male is about 300 N. One solution would be to use linear actuators, however these are expensive in terms of trying to achieve our production cost of $50. By employing the use of a rack and pinion system with gripping arms attached and a gearbox attached to its motor, we can achieve that grip strength. Lastly, for the vertical movement of either the bottle or the assembly that opens the bottle, we can achieve that using either 1) a pulley system or 2) a threaded rod with linear guides (similar to a CNC machine) that is powered by a motor.

Risks & Countermeasures:

• Over-torquing or under-torquing of the product.
  • Ensure that the gearbox is providing a sufficient gear ratio and either limit the range of motion or employ a feedback sensor to control the motor.
• Using 3 motors - more room for errors
  • Ensure that power supply is sufficient and that the timing of all the motors is appropriate based on trial and error testing.

Need 2: Arm Actuator for Radial Nerve Palsy

Problem Statement:

• There is a large number of people who need some type of device that can help with an active form of recovery for radial nerve injuries.

Target Audience

• People who suffer from upper arm damage have a difficult time manipulating their arm because they have nerve damage in the arm that limits the range of motion in flexion and extension.
• About 30% of Major League Baseball players face limited range of motion in the upper arm flexion and extension for the average age of 26.
• Very common injury with contact sports players and car crash victims.

Functional Requirements

• Able to assist with creating + or - 1.5 Nm torque in the wrist
• Provide a steady speed of 5 mm/s to the wrist
• Able to offer resistance against motion
• Be ergonomic for the user
• Able to fit on the forearm of the user
• Lightweight, less than 3 pounds

Solutions

Analysis/ Feasibility

• We need to know the range of motion of a non-injured person.
• We need to know the motion speed
• It takes maximum flexion torque ranged from 5 to 20 Nm, and the maximum extension torque ranged from 3 to 14 Nm.
• Test light weight material that is also very durable and flexible

Risks and Countermeasures

• R: The actuators moving too fast - causing further injury
  • C: the actuator has a manual mechanism to adjust the speed
• R: The actuators producing too much force - causing further injury
  • C: A limiter to limit the amount of force being produced
• R: The actuator overheats from repetitive use
  • C: cooling or rest period on the actuator before it overheats

Need 3: Snow Removal Robot

Problem Statement:

• Snow removal can be daunting, time consuming task which requires the repeated process of pushing, lifting, and pulling to effectively remove snow.

Target Audience

• According to the American Journal of Emergency Medicine, about 4.5 for every 100,000 people get injured while using a snow shovel, with the most common injuries being sprains, strains and concussions.

Functional Requirements

• Be able to push 7kg of snow off of path
• Be able to move at a constant 0.3 m/s speed
• Be able to dispense salt at a rate of 0.03 kg/s
• Be module in design with no more than 25 parts
• Device weighs no more 20 kg (unloaded with salt)
• Device is no bigger than 0.5m length by 0.75 m width by 0.5 m height
• Costs less than $200.
• mechanics/electronics must be contained to prevent water damage

Solutions

Analysis/ Feasibility

• We assumed that the user would like a 0.5m x 0.5 m path cleared on the sidewalk.
• We assumed the response time for someone to start shoveling snow is approximately 10 mins. The largest recorded precipitation amount in Chicago in that interval was 1.97 in, or 0.05m.
• Assuming the snow is evenly spreaded out, the average volume of the snow 0.0125m³.
• The density of snow is 481 kg/m³, which results in ~6.01kg of snow, a value of which is lower than the functional requirement of 7kg.

Risks and Countermeasures

• Device pushes snow into a pile that is more than 7 kg in weight
  • Device could have sensor to indicate when push load to the side and start a new pile
• Device has corners where parts meet, causing a gap that snow/water can leak in
  • We use a protective coating or make the outer shell in one, continuous piece

Feedback from Week 5 Presentation:

• The drawings need to be more detailed - provide a better explanation of how it’ll work.
• The analysis needs to be more quantitative and detailed.
• Overall, we need to be better prepared for Week 7’s presentation and be more objective of our decisions (question and justify why we chose that).