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02.22.08
RP1
1kg Motor Module, First Generation
P08208 – Mechanical DesignP08205 – Wireless & PWM Motor Controller
MSD I
20072
02.22.08
WHAT IS A MOTOR MODULE ?
DRIVE
MODULAR MOUNTING
STEER
aka “MM”
02.22.08
1kg
10kg
100kg
OFF THE SHELF MOTOR MODULES
02.22.08
RP100( Wired )
RP10( Wired )
RP1Sister projects!
RP10Redesig
n
02.22.08
RP10Redesig
n
RP1
Wireless!
Robust!
Autonomous!
Smaller! Lighter!
02.22.08
ORGANIZATION BREAKDOWN
P08208Wendy Fung
P08205Reid Williamson
SteerMatthew BenedictArtur Ponikiewski
DriveAndrew AndersonMatthew BenedictPlatform
Eric RodemsArtur Ponikiewski
YokeJames EdickEric Rodems
ElectronicsBryan Jimenez
Jonathan Maglaty
ControlsBrendan HayesPhilip Edwards
02.22.08
System-Level Process Flow
Computer
Wireless Receiver
Microprocessor
Motor Controller
RP1 Motor Module
02.22.08
CRITICAL REQUIREMENTS
• Transport 1kg Payload• Robust = Withstand Tabletop Drop• Wireless Communication• Power Motors with a PWM Signal• Open Source & Open Architecture• Reflect Design of the RP Family• Modular Design for Multiple End Uses
02.22.08
EXPECTATIONSo Quantity
2, Fully Functional
o Size12in x 6in x 6in
o Speed @ max efficiency 38 in/s
o Droptest Repair Time < 5 min
o Wireless Range 300 ft max
o Battery Life 1 hour +
1
2
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FORMAT
Drive & Steering• Q & A
Yoke & Platform• Q & A
Electronics & Controls• Q & A
DFMA & MSD II Outlook• Q & A
02.22.08
• Responsibilities: – Highly dynamic range of operating speeds– An array of different operating conditions– Robustness– Seamless system integration
• Risks– Difficulty obtaining different motor gearboxes– Drive Shaft Alignment (turntable wobble)– Robustness of design– Accurateness of systems modeling– Tolerances– Assembly
DRIVETRAIN SYSTEM
02.22.08
IG 32 Motor
27:1 Gear Reduction
¼” Stainless Steel Axles
½” Aluminum Spacers
2” Diameter Wheel
Axle Couplings
Thrust Bearings
2:1 Synchronous Belt and Pulley
Axle Collars
FINAL DESIGN
02.22.08
Efficiency vs. Torque
52
53
54
55
56
57
58
59
60
61
0 2 4 6 8 10 12
Torque (lb*in)
Eff
icie
ncy
(%
)
5:1
14:1
19:1
27:1
51:1
71:1
100:1
139:1
189:1
SYSTEM LEVEL DESIGN
02.22.08
Power vs. Torque
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0 5 10 15 20 25
Torque (lb*in)
Po
wer
(W
)
5:1
14:1
19:1
27:1
51:1
71:1
100:1
139:1
189:1
SYSTEM LEVEL DESIGN
02.22.08
STEERING
• Responsibilities: – Infinite Steering– Easy to assemble/disassemble– Robust– Seamless system integration
• Risks– Robustness of belt tension system– Turntable – Integration with electronics and controls– Tolerances– Assembly
02.22.08
IG 32 Motor
71:1 Gear Reduction
¼” Stainless Steel Axles
Turntable
Custom Centerpost
1:3 Synchronous Belt and Pulleys
STEERING SUBSYSTEM
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STEER BELT TENSION
Axle Couplings
Adjustable Steer Motor Mounting Plate
Adjustable Bearing Plate
02.22.08
DRIVE & STEERING
Q & A
02.22.08
YOKE
02.22.08
YOKE
• Responsibilities: – Responsible for structural skeleton of Rp1– Design a rigid and robust framework– House all other sub-systems within framing – Provide protection against a 36” drop to the floor
• Risks– Keeping within the weight requirements– Withstand drop without any significant damage or
misalignment of components – Minimizing overall cost of yoke
02.22.08
UPPER YOKE
1/8” AL Plate
½” x ½” Al Posts
AL Angle Brackets
1/8” Al Upper Yoke to Turntable Mounting Plate
Encoder standoff mounting plate
1/8” Al Motor Mounting Plates
02.22.08
LOWER YOKE
1/8” Al Upper Yoke to Turntable Mounting Plate
80/20 90° Base Connector
1”x1” AL 80/20 Quick Frame
Mounted Flanged sleeve bearings
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Design Justification
• Critical Decisions:– Frame built of aluminum instead of Lexan to
improve strength– Used an open 80/20 fork design for lower yoke
to provide maximum rigidity while minimizing weight
– Used solid post box design in upper yoke to fully enclose drive, steering and electrical systems. Solid posts allows for easier hardware attachment
– Turn table connected to mounting plates on both sides to support upper and lower yoke
02.22.08
PLATFORM
• Responsibilities– Platform design– Mounting of modules to platform– Idler module development– Test fixture design
• Risks– Design was heavily reliant on upper
yoke– Design of platform for drivability
02.22.08
DRIVE PLATFORM
2 platforms (1 per team)
– Holds 2 motor modules
– Holds 2 idler modules
– Square shape for adaptability
02.22.08
IDLER MODULE
Idler Design– Past RP project
experience– Use of motor
module parts– Simplified design– Caster offset
(slot)
02.22.08
TEST PLATFORM
1 test platform– Holds 1 motor
module– Holds 2 idler
modules– Will have quick
connect adapters spec’d out from Molex
02.22.08
YOKE & PLATFORM
Q & A
02.22.08
CONTROLS
• Graphical User Interface (GUI)– Allow the user to interact with and
control the robotic platform• Wireless
– Responsible for the communication between the user and the platform
• Microprocessor– Generate control signals and monitor
sensor feedback
02.22.08
Controls
• Risks– GUI
• User is unaware of current state of RP1• User is unable to respond quickly
– Wireless• Wireless interference• Insufficient data rate
– Microprocessor• “Swamped” with encoder feedback
02.22.08
• Final Design
GUI
Left Motor Module Drive Motor: Good
Wheel Angle
Battery Life Remaining
Left Motor Module Steering Motor: Good Right Motor Module Drive Motor: InefficiencyRight Motor Module Steering Motor: Good
02.22.08
Wireless
• MIB520 USB-Gateway
• MICAz 2.4 GHz Wireless Transceiver
02.22.08
• Freescale MC9S12DT256– 8 Channel PWM Module– Modular Communication
• IIC• SPI• SCI• CAN
Microprocessor
02.22.08
ELECTRONICS
• System Responsibilities– Provide components for motor control– Placement of motor control components – Supply power to electrical components– Confirm electrical components are compatible
with microprocessor
• Risks– Component ratings (i.e. heat, amps, etc.)– Lead time on final part selections– Compatibility between electrical components
02.22.08
Final Design
• H-bridge – PWM Motor
Controller 3A
• Encoders– US Digital
•EM5•EM1•HUBDISK
02.22.08
Final Design
• Power Schematic for encoders (5V)
02.22.08
Final Design
• Simulation for Encoder Power Schematic
02.22.08
Final Design
• Battery Selection– NiMH– 24V– 3.5Ah– Rechargeable
02.22.08
CONTROLS & ELECTRONICS
Q & A
02.22.08
Design For Manf. & Assembly
• Steering assembly implementation
• Degree of machining precision• Bending of motor shaft• Spacing and fasteners• Control Communication• Functional control
02.22.08
Plans for MSD II
• Build RP1 prototype• Test accuracy of
system modeling• Build test fixture• Do the drop test• Look into possible
aesthetical improvements
• Optimize current design
• Build GUI• Setup basic
wireless communication
• Test all electrical components
• Full system integration and test