Stair Climbing Robot Team 7 Senior Design Project Dalhousie University Dept. of Mechanical Engineering Fall 2008

Introduction Design Requirements Design Selection Final Design Budget Conclusions Introduction Team members: Janet Conrad, Jason Lee, Stanley Selig, Evan Thompson, Dylan Wells Supervisor: Dr. Ya-Jun Pan

Introduction Design Requirements Design Selection Final Design Budget Conclusions Design Requirements RobotWeight of 60 kg Height/Width less than standard door Payload Weight of 12 kg Footprint of 400 X 400 mm Climb and descend stairs Self-leveling payload platform Powered by standard AC electricity Safe 150 mm 300 mm

Major design considerations when designing alternatives Ability to carry payload Speed and smoothness of climb Weight Weight distribution and tipping Power needs and power distribution Modularity Introduction Design Requirements Design Selection Final Design Budget Conclusions Design Selection Major Considerations

(1) Linear Actuator Sensors control platform angle Pros – store-bought Cons – difficult to code; costly Design Selection Alternatives – Payload Leveling System (2) Cradle Leveler Platform in cradle freely rotates Pros – self levels; no programming Cons – center of gravity; difficult to control damping Introduction Design Requirements Design Selection Final Design Budget Conclusions

(1) Treads Parallel treads Pros – simple; store-bought Cons – may slip; requires more power on flat plane (2) Corkscrew Small wheels in helix shape Pros – ‘wow’ factor; unlikely to slip backward Cons – construction; wobble Introduction Design Requirements Design Selection Final Design Budget Conclusions Design Selection Alternatives – Stair Climbing Drive

The payload platform is automatically leveled by gravity using two curved guide rails fixed to the top of the frame. As the robot climbs, the platform is free to roll within the rails and will remain level with the horizontal. Introduction Design Requirements Design Selection Final Design Budget Conclusions Final Design Rail Leveling System

The optimum radius calculated from this angle is 261 mm. Opted to use θp = 50° to have sufficient moment arm length and to minimize θ associated with arc length (140 for θp = 50°) for decreased fabrication time, cost and difficulty. Introduction Design Requirements Design Selection Final Design Budget Conclusions Final Design Rail Leveling System

Finite Element Analysis in UG NX 5.0 used to determine dimensions of components based on maximum deflection Performed mesh convergence studies to determine appropriate element sizes Modeled rails and platform using 2D Thinshell elements Rails Determined that supports should be located on either side of applied force from platform to minimize deflection Platform Determined thickness of platform to be >2 mm to minimize centre deflection of plate with maximum payload Introduction Design Requirements Design Selection Final Design Budget Conclusions Final Design Finite Element Analysis of Leveling System

The Tri-wheel assembly is motorized through a drive shaft connected to the central ‘sun’ gear All wheels are driven at equal speed via the rotation of the central gear Pros: smooth climbing; good lateral stability; maneuverability on flat ground Cons: complex design; difficult to manufacture Introduction Design Requirements Design Selection Final Design Budget Conclusions Final Design Tri-wheel Stair Climber

The dimensions of all components must be contained within the faceplate dimensions to avoid interference with the stairs. Introduction Design Requirements Design Selection Final Design Budget Conclusions Final Design Tri-wheel Stair Climber

Wiper motors have been chosen to provide the motive power for the machine, due to their price, availability, pre- existing worm-gear reduction, and 2-speed setting. The wiper motors will be fixed to a 40 chain double sprocket, sending one chain to the front wheel and one to the back. Introduction Design Requirements Design Selection Final Design Budget Conclusions Final Design Drive System

The guide rail and the Tri-Wheel modules will be fixed to a robust aluminum skeleton using standard M8 nuts and bolts. Introduction Design Requirements Design Selection Final Design Budget Conclusions Final Design Complete Assembly

Maximum $2500 Level Up Budget ItemCost/Unit# unitsCost Gears Wheels Bearings Raw Materials2001 Drive Shaft Speed Controller1001 Electric Motor Replacement of Parts1001 Nuts/Bolts/Bits&Bobs908 Chain Sprocket10880 Wiring/Chain/Cords501 Total Cost$2,500 Introduction Design Requirements Design Selection Final Design Budget Conclusions Budget

Introduction Design Requirements Design Selection Final Design Budget Conclusions Future Considerations Final torque and RPM values Frame support locations Controller device

Introduction Design Requirements Design Selection Final Design Budget Conclusions Projected to satisfy all design requirements set out in September. Designed to test design concepts Design can be scaled up to carry a considerable amount of weight.

Introduction Design Requirements Design Selection Final Design Budget Conclusions Thank you Shell Canada Dr. Ya-Jun Pan Dr. Julio Militzer L. E. Cruickshanks Sheet Metal Dalhousie Mechanical Engineering Department

Stair Climbing Robot Team 7 Senior Design Project Dalhousie University Dept. of Mechanical Engineering Fall 2008 Questions?