Vehicle Automatic Seating System Computer Aided Design Fall 2004 Marian Rodríguez Rebeca RiveraCésar Morales University of Puerto Rico Mayaguez Campus Mechanical Engineering Department

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Problem Description Problem Description Design a mechanism that will provide the mobility to the disable and aging people to handle how to get in and out the car without that much effort.

Expected Outcomes  Provide a better quality of life for those who constantly need assistance to sit and stand from a vehicle’s seat.  Guarantee that the person sits and stands from their seats in the safest possible way with or without help.  The person helping will be also beneficiated because his or her function will only be to maintain the person in the right direction towards or away the seat.

Design Selection-Idea #1  The seat of the car mounted on a lifting device  Lift the seat while outside the car a maximum of 45°  A rotating mechanism  A torque motor that will aid the sliding movement  Sliding fixture  Allow the seat to slide to the side out of the car  Provide the action of back and forth movement within the car  A lifting device will lift the seat while outside the car a maximum of 45°.

Design Selection-Idea# 2  The seat of the car mounted on a lifting device  Lift the seat while outside the car a maximum of 45°  Sliding fixture  S shape railings to aid for the back and forth movement along with taking the car outside the car  A lifting device will lift the seat while outside the car a maximum of 45°.

Design Criteria Criteria Weight Model 1 Model 2 Datum %AutomatedManual Cost1500 Control2510 Space1300 User friendly 2010 Maintenance8000 Safety7100 Manufacturing12000 Total

Design Problem  Analysis of the sliding mechanism is critical for safety and reliability.  The x-direction rails and guide blocks surfaces are in constant contact with each other suffering wearing, fatigue and bending.

Material Selection Evaluation index Candidate Materials Ultra High Strength Steel StainlessSteelLow Carbon Steel Ultimate Strength, psi 287,000206,00061,000 Yield Strength, psi 270,000173,00051,000 Young’s Modulus, psi 30x x x10 6 Hardness, BNH Cost, US$/lb Machinability The stress in a cantilever beam due to yielding: Material Selected: AISI 1020 It is assumed that VASS will be used 10 times a day for 25 years. The cyclical stress at 10 5 cycles of failure is 38,000psi.

Optimization where, E is known as the Young’s Modulus of AISI 1020 P is the applied load at two different points ais the distance from the fixed end to the first applied load P bis the distance from the fixed end to the second applied load P lis the length of the cantilever beam Iis the moment of inertia of the beam δis the deflection at the end of the beam

Constraints Equality Constraints Inequality Constraints

Finite Element Method

Results and Discussion Present Design  x*= { } T  The deflection occurred at the free end as expected from a cantilever beam.  The deflection is so small, δ = in, that guarantees that the guide block will not deflected.  FEM Analysis shows that large blue areas are predominant; indicating an over design.  In order to minimize the blue colors in the stress gradient, modification to the cross-sectional area could be performed.

Cost Analysis

Conclusion and Recommendations  VASS offers: –A new perspective and opportunity for people with disabilities –A revolution and break all the standards previously set by society –A guarantee that for every individual the same opportunities in social life will be available  Mechanical components needed to be optimize: –The lifting mechanism –The servomotor and torque motor –The Ball Screws

Final Thought “The freedom that VASS provides is priceless. There are lots of things to see out there; so do not limit yourself, the sky is the limit”

Questions ?