Curtis Gittens Daniel Goundar Daniel Law Johannes Minor April 14 th 2008

The Team Curtis Gittens  Electronics  Microcontroller Programming Dan Law  Electronics  Parts Selection & Purchasing Johannes Minor  SolidWorks  Controller Design Daniel Goundar  SolidWorks  Adhesives & Passive Pre-loading

Outline Motivation System Overview Design & Implementation  Structural/Mechanical Design  Electronics Subsystem  Control System Timeline and Finances Future Development  Market Outlook/Research Opportunities What we have learnt as a Team Conclusion  Acknowledgements  Questions

Motivation Useful in hostile & inaccessible environments Can substitute robots where human safety would be at risk Diverse applications (inspections, research, maintenance) Large increase in research into highly mobile robots, capable of navigating both natural and artificial terrain Rapidly growing field of research, little product development

Solution Small robots that can navigate man made environments, without being impeded by walls and corners Light-weight, durable, and autonomous Wall scaling using passive adhesives Mobility in two dimensions on horizontal and vertical surfaces Inexpensive commercial wall-climbers

System Overview Functional Requirement Summary  Diverse mobility  Scalability

Design & Implementation: Module Design Iterations First Iteration: Drive Belt System Motor Mounted in Center Optical Encoder shaft passes through axle Spring loaded front axle Spindly chassis supports Weight: 45g Second Iteration: Motor attached directly to wheel More integrated optical encoder Improved strength in spring axle More robust chassis Reduced wheel-channel depth Weight: 41g Final Iteration: Light-weight dual potentiometer design Identical front end Substantial weight savings Weight: 31g

Design & Implementation: Single Module Design

GM14a Gear Motor Two rotary Potentiometers, 180 degrees out of phase Track Belt Drive Wheel Spring-loaded front axle to keep track belt in tension

Design & Implementation: Inter-Module Connections

Design & Implementation: Tail Design

Design & Implementation: Adhesive Selection Used a variety of household adhesives Varying results (scotch & carpet tape, foam, rubber cement) Issues with adhesive separating from belts Carpet tape was the final choice of adhesive

Design & Implementation: Electronic

Design & Implementation: Electronic Component Selection Microcontroller- TI MSP430F169  Hardware timers for motor drive and input sampling  12 bit ADC  Hardware multiplier Analog Multiplexers - DG408  Just your standard 8x1 Analog Mux H-bridges - L293D  Quad Channel Push button remote

Design & Implementation: Software Interrupt driven Scalable Digital filtering of potentiometer feedback Fixed point signal processing

Design & Implementation: Single Module Speed Control

Design & Implementation: Smooth Turning Algorithm

Timeline

Budget DescriptionBudgeted Cost Total CostCost for 6 Modules Power Supply$30.00$0.75$0.00 Microcontroller$60.00$151.50$47.00 Misc. Electronic Components$20.00$85.00$45.00 Motors and Actuators$300.00$263.60$ Rapid Prototyping$300.00$315.75$ Adhesive$5.00$30.00$5.00 Sensors$60.00$135.80$22.32 Contingency$50.00 $0.00 Total$825.00$1,032.40$350.03

Funding DescriptionBudgeted Amount Actual Amount Engineering Science Student Endowment Fund$250.00$ Departmental Funding$50.00$40.00 Group Funding$225.00$ Sponsorship from Dr. Carlo Menon$300.00$ Total$ $1,032.40

Market Outlook/ Research Opportunities Nuclear power plant inspection Space research Maintenance on tall structures

Future Development Autonomous control Active pre-loading Advanced Adhesives

What We Have Learnt Difficult to design in parallel when electronics and mechanical designs require integration from the start Signal noise manages to creep into most everything Shipping inflates total cost of components Budgeting for time improves with experience Debugging and tweaking takes bulk of development time

Acknowledgements Dr. Carlo Menon  Input and feedback on design choices Gary Houghton  Rapid prototyping of plastics ESSEF Endowment Fund  Funding ($470.00)

Questions Videos and Demonstration

Appendix Performance Summary Technical Information: Results Financial Details

Performance Summary PerformancePrototype Specifications Measured MTTF2 minutes > 5 minutes Max Speed1 cm/s5.7 cm/s Turning Radius75 cm 90° transition3x22x2

Technical Information: Results

DescriptionQuantityUnit PriceCost Power Supply $0.75 discarded batteries10$0.00 battery clip (2x AA)1$0.75 Microcontroller $ MSP430F1693$30.00$90.00 Multiplexers2$2.50$5.00 H-Bridges3$4.50$13.50 Programming Cable1$25.00 Voltage Regulator6$3.00$18.00 Misc. Electronic Components $85.00 Parts from Fred $35.00 Headers/Sockets $50.00 Motors and Actuators $ GM12a1$15.00 GM14a9$15.00$ Belts, pulley, U-joint $ Springs34$0.40$13.60

Description QuantityUnit PriceCost Rapid Prototyping $ Rapid Prototyping $ Aluminum Bars 7$2.25$15.75 Adhesive $30.00 Various tapes and glues $30.00 Sensors $ Rotary Potentiometers 30$1.86$55.80 Optical Encoders 3$20.00$60.00 Contact Encoders 10$0.50$5.00 Light/IR sensor $15.00 Contingency $50.00 Total$1,032.40

DescriptionQuantityUnit PriceCost Power Supply $0.00 discarded batteries 10$0.00 Microcontroller $47.00 MSP430F169 1$30.00 Multiplexers 2$2.50$5.00 H-Bridges 2$4.50$9.00 Voltage Regulator 1$3.00 Misc. Electronic Components $45.00 Parts from Fred $35.00 Headers/Sockets $10.00 Cost for 6 Modules

Description QuantityUnit PriceCost Motors and Actuators $ GM14a 6$15.00$90.00 Belts 5$6.00$30.00 Springs 12$0.33$3.96 Rapid Prototyping $ Rapid Prototyping $ Aluminum Bars 3$2.25$6.75 Adhesive $5.00 Carpet Tape 1$5.00 Sensors $22.32 Rotary Potentiometers 12$1.86$22.32 Total$350.03

Sample Second Order Filter Output