Stair Climbing RobotTeam 7
Senior Design ProjectDalhousie UniversityDept. of Mechanical EngineeringFall 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
•Robot Weight of 60 kgHeight/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 SelectionMajor Considerations
(1) Linear Actuator• Sensors control platform angle• Pros – store-bought• Cons – difficult to code; costly
Design SelectionAlternatives – 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
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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 SelectionAlternatives – 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
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Final DesignRail 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
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Final DesignRail 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
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Final DesignFinite 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 DesignTri-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
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Final DesignTri-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
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Design Selection
Final Design
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Final DesignDrive System
The guide rail and the Tri-Wheel modules will be fixed to a robust aluminum skeleton using standard M8 nuts and bolts.
Introduction
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Design Selection
Final Design
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Final DesignComplete Assembly
Maximum $2500
Level Up Budget Item Cost/Unit # units Cost Gears 25-40 28 940 Wheels 30 12 360 Bearings 10 36 360 Raw Materials 200 1 200 Drive Shaft 30 4 120 Speed Controller 100 1 100 Electric Motor 50 2 100 Replacement of Parts 100 1 100 Nuts/Bolts/Bits&Bobs 90 8 90 Chain Sprocket 10 8 80 Wiring/Chain/Cords 50 1 50
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
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 PanDr. Julio MilitzerL. E. Cruickshanks Sheet MetalDalhousie Mechanical Engineering Department
Stair Climbing RobotTeam 7
Senior Design ProjectDalhousie UniversityDept. of Mechanical EngineeringFall 2008
Questions?