• A design concern is a specific aspect or consideration that needs attention during the design process. 
  • If the design concern is a requirement, the requirement lists the value of the assessment measure that must be achieved. 
  • If the design concern is a goal, there is not a certain value. Instead, it is the desired direction of the assessment measure in order to come closer to achieving the goal. 
DESIGN CONCERNS CATEGORIES DESIGN CONCERNS ASSESSMENT MEASURES
DEFINITION REQUIREMENT GOAL
Physical Lightweight Weight of walker (lb) XXX minimum
Structural Fatigue Resistance to failure during cyclic loading (ISO 1119-1:1999) Load of 800N at 200,000 cycles and 1 Hz XXX
Static Leg Strength Load is applied 10mm above bottom of leg directed towards the center of the frame. Load force is applied gradually over 2s and held for 5s. (ISO 1119-1:1999)  300-500N XXX
Seat Strength Ability to support at least 350 lbs (Medicare A52503) 350lb during Three Point Bend Test XXX
Stability Tilt frame at different angles forward, backward, and sideways with a vertical load (ISO 1119-1:1999) 250 N XXX
Environmental Water Resistant Flexural strength (ASTM D790) retained after being submerged in water for 24 hours (%) 90 XXX
UV Resistance Flexural strength following extended period of UV exposure (%) (ASTM G154, 3 day test) 90 XXX
Human Engineering Ergonomics Misalignment of hand to wrist that causes least amount of strain XXX minimum
Accessibility to controls Distance hand has to travel to engage gears and/or brake (in) XXX minimum
Life Cycle Warranty Duration of warranty Lifetime XXX
Cost Affordable price Cost before Medicare Coverage (80%) $450 minimum

Updated 04/23/2024