rp1

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

02.22.08

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

02.22.08

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

02.22.08

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