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Stair Climbing Robot Team 7 Senior Design Project Dalhousie University Dept. of Mechanical Engineering Winter 2009.

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Presentation on theme: "Stair Climbing Robot Team 7 Senior Design Project Dalhousie University Dept. of Mechanical Engineering Winter 2009."— Presentation transcript:

1 Stair Climbing Robot Team 7 Senior Design Project Dalhousie University Dept. of Mechanical Engineering Winter 2009

2 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

3 Design Fall final design This is where we were at the end of last semester… Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

4 Design …and where we are now 5 Major Component Groups Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

5 Design 5 Major Component Groups Tri-Wheels Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

6 Design 5 Major Component Groups Tri-Wheels Drive System Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

7 Design 5 Major Component Groups Tri-Wheels Drive System Leveling System Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

8 Design 5 Major Component Groups Tri-Wheels Drive System Leveling System Frame Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

9 Design 5 Major Component Groups Tri-Wheels Drive System Leveling System Frame Controller Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

10 Design Components – 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

11 Design Components – Tri-wheels Tri-Wheel Components Faceplates Gears and Wheels Cantilever Mount Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

12 Design Components – 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

13 Design Components – 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

14 Design Components – 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

15 Design Components – 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

16 Design Components – 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

17 Design Components – 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

18 Design Control 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 Battery Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

19 Testing Summary 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

20 Testing Summary 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

21 Testing Control 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

22 Testing Ascent & 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

23 Testing Ascent & 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

24 Testing Ascent & Descent - 25 lb Weight Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

25 Testing Ascent & 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

26 Testing Repeatability 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 11:33 21:20 31:50 Run # (Descent)Time 11:15 20:55 30:45 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

27 Testing Maximum Payload Weight Incremented weight up to 115 lb payload (almost 5x design requirement) Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

28 Design Requirements Design RequirementStatusPass? Robot must weigh less than 60kg Weight – 29.5kg (2x lighter than required!) Robot must fit through door (0.91m x 2.03m) Width – 0.83m Height – 0.53m Robot must be less than 2m length Length – 1.08m (Only ½ the maximum length!) Robot must carry payload of 12kg Payload kg (4.5x heavier payload than required! ) Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

29 Design Requirements Design RequirementStatusPass? 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

30 Design Requirements Design RequirementStatusPass? Robot must be user operated with handheld controller RC transmitter tested and works Power supplied from AC socketBattery powered – more mobility An operations manual will be providedOps manual written 1 year lifetime with no maintenanceNo failing components yet Total Requirements Met: 12/12 Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

31 Budget Overview 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 – Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

32 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

33 Angus, Albert, and Mark Jon MacDonald, Dylan Scott, Julian Ware, Colin O’Flynn Peter Jones Dr. Ya-Jun Pan Dr. Julio Militzer Introduction Design Testing/ Performance Design Requirements Budget Future Work Thanks

34 Stair Climbing Robot Team 7 Senior Design Project Dalhousie University Dept. of Mechanical Engineering Winter 2009 Questions?


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