stair climbing robot team 7 senior design project dalhousie university dept. of mechanical...
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Stair Climbing RobotTeam 7
Senior Design ProjectDalhousie UniversityDept. of Mechanical EngineeringWinter 2009
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Introduction
Team members:
Janet Conrad, Jason Lee, Stanley Selig, Evan Thompson, Dylan Wells
Supervisor:Dr. Ya-Jun Pan
Thanks
DesignFall final design
This is where we were at the end of last semester…Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Design…and where we are now
• 5 Major Component Groups
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Design
• 5 Major Component Groups• Tri-Wheels
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Design
• 5 Major Component Groups• Tri-Wheels• Drive System
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Design
• 5 Major Component Groups• Tri-Wheels• Drive System• Leveling System
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Design
• 5 Major Component Groups• Tri-Wheels• Drive System• Leveling System• Frame
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Design
• 5 Major Component Groups• Tri-Wheels• Drive System• Leveling System• Frame• Controller
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
DesignComponents – Tri-wheels
• Three-wheeled design
• Planetary gear configuration driven by central gear from drive-train
• Will drive along flat ground by spinning all wheels
• Front wheel climbs stairs when contacting stair due to friction
• Entire tri-wheel rotates about its axis, mounting the stair
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
DesignComponents – Tri-wheels
•Tri-Wheel Components• Faceplates• Gears and Wheels• Cantilever Mount
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
DesignComponents – Tri-plates
• Profile designed to avoid interference with stair’s right angle
• Complex profile cut from 3/16” Al sheet metal at L.E. Cruickshanks Sheet Metal Ltd. using a plasma cutter
• One central bearing to facilitate rotation of the tri-wheel assembly about the main axis
• Three 3/8” bearings to support wheel shafts
• Bearing seats fixed to tri-plates
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
DesignComponents – Gears & Wheels
• 20 pitch, hardened steel, turned down to reduce weight
• Idler gears – bored out to seat bearings which rotate on fixed posts
• Wheels are Abec 11 ‘Flywheels’ skateboard wheels
• 97mm, chosen for high coefficient of friction
• Fixed rigidly to wheel shafts
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
DesignComponents – Cantilevered Pipe Mount
• Tri-wheel assembly rotates around the outside
• Drive shaft rotates inside supported by bearings at either end
• Attaches to underside of frame with carriage bolts
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
DesignComponents – Drive train
• One windshield wiper motor from 1994 Ford Tempo mounted on each side
• ANSI 25 chain connects a small sprocket (14 tooth) to a large sprocket (26 tooth) for gear reduction
• Lateral mounting of motors allows skid steering
• Shafts made of steel, with custom threading and keying
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
DesignComponents – Leveling System
• Finite element analysis used in design
• Curves designed for ISO stair angles
• Curved rails fabricated using roller mill at L.E. Cruickshanks
• Platform keeps payload level during ascent and descent of stairs
• Platform covered with high-friction liner to prevent payload from sliding
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
DesignComponents – Frame
• Constructed of 1” aluminum square stock
• Lightweight frame
• Facilitates ease of mobility
• Modular design allows mounting of custom parts and different configurations
• Frame was welded together and is very robust
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
DesignControl system
• Sabertooth speed controller controls motors on each side
• Permits skid steering and straight driving
• Controlled with an RC transmitter
• Operated from safe position
Receiver
Motor Driver
Transmitter
Motor MotorBattery
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Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
TestingSummary
• Most tests conducted are qualitative, as most of the components of our robot are purely mechanical in nature
• Control tests included:• Connecting motors to battery
• Adjusting motor speeds with potentiometer
• Testing RC transmitter and receiver
• Measuring current draw from loaded motor
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
TestingSummary
Climbing and drive tests included:
• Powering wheels while robot is on blocks
• Straight line motion test high/low speed
• Turning on the spot
• Turning while driving
• Stair descent & ascent - no payload
• Stair descent & ascent - required payload
• Determination of maximum payload weight
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
TestingControl Tests
• Connected the motors and speed controller to a power supply and controlled with two potentiometers.
• Motors worked as expected for low-speed.
• Connected the receiver and transmitter to motor driver inputs.
• Robot controlled as expected. Some electrical interference.
• Placed ammeter in motor circuit
• Maximum current draw was 8 A.
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
TestingAscent & Descent – Tile Surface
• Tested climbing stairs around campus
• Not enough friction generated at wheel/stair interfaces
• Front wheel skids instead of locking
• Motor power transmitted to spinning front wheels
• Locked gears to test concept
• Tri-wheel pivoted as expected
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
TestingAscent & Descent - Concrete
• Attempted climbing another set of stairs with payload
• Found flight with appropriate dimensions for our robot
• Concrete stairs provided better friction and less traffic
• Climbed the 7 stair flight from bottom to top
• Repeatability will be discussed after testing video
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
TestingAscent & Descent - 25 lb Weight
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
TestingAscent & Descent – Payload Leveling
• High-friction liner used for damping and friction
• Minimal plate bending at operating loads
• ~5 deg change in plane during normal operation
• Dampens quickly with very little overshoot from center
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
TestingRepeatability
• Ascended 7 stair flight in average time of 1 minute 34 seconds with 25 lb payload
• This represents travel time of 4.5 stairs per minute on average
Run # (Ascent) Time
1 1:33
2 1:20
3 1:50
Run # (Descent) Time
1 1:15
2 0:55
3 0:45
• Descended 7 stair flight in average time of 58 seconds with 25 lb payload
• This represents travel time of 7.2 stairs per minute on average
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
TestingMaximum Payload Weight
• Incremented weight up to 115 lb payload (almost 5x design requirement)
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Design Requirements
Design Requirement Status Pass?
Robot must weigh less than 60kg
Weight – 29.5kg(2x lighter than required!)
Robot must fit through door (0.91m x 2.03m)
Width – 0.83mHeight – 0.53m
Robot must be less than 2m length
Length – 1.08m(Only ½ the maximum length!)
Robot must carry payload of 12kg
Payload - 52.5kg(4.5x heavier payload than required! )
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Design Requirements
Design Requirement Status Pass?
Robot must ascend stairs at a rate of no less than one stair per minute
4.5 stairs per min(4.5x faster than req’d!)
Robot must descend stairs at a rate of no less than one stair per minute
7.2 stairs per min(7.2x faster than req’d!)
Robot must be able to self-level a platform upon which a payload sits
Created, tested, and works
Robot must be able to carry a 400x400mm payload
Payload can fit on platform
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Design Requirements
Design Requirement Status Pass?
Robot must be user operated with handheld controller
RC transmitter tested and works
Power supplied from AC socket Battery powered – more mobility
An operations manual will be provided Ops manual written
1 year lifetime with no maintenance No failing components yet
Total Requirements Met:12/12
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
BudgetOverview
• Budget awarded last semester was $2500
• Summary of the main expenses shown
• More than $500 under budget
• Savings from:• Better value components • Majority of raw materials
donated by L.E. Cruickshanks Sheet Metal Ltd.
• For more detailed budget, consult the final report on our website – www.tinyurl.com/levelupgroup
Cost791445336105
322
Budget
WheelsMotors
Main Expenses
ItemGearsControls
$2,500
Everything Else
Total Cost $1,999
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Future Work/Considerations
• Gear locking mechanism to rotate entire tri-wheel when desired
• Covering to protect/weatherproof electronics
• High quality receiver to allow wireless high/low speed switches
• Damping mechanism for guide rails
• Payload platform walls/ straps
• Mount batteries on frame
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Thanks
Angus, Albert, and MarkJon MacDonald, Dylan Scott, Julian Ware, Colin O’Flynn Peter Jones Dr. Ya-Jun PanDr. Julio Militzer
Introduction
Design
Testing/Performance
Design Requirements
Budget
Future Work
Thanks
Stair Climbing RobotTeam 7
Senior Design ProjectDalhousie UniversityDept. of Mechanical EngineeringWinter 2009
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