P07202: Motor Module – Robotic Platform 100kg Robert Saltarelli:Project Manager Erich Hauenstein:Mechanical Member Dustin Collins:Mechanical Member Jasen Lomnick:Mechanical Member Saul Rosa:Electrical Member Derrick Lee:Electrical Member Muhammad Moazam:Electrical Member Vincent Capra:Electrical Member Sponsor: Gleason Foundation

P07202: Functionality

P07202: Mechanical Design

Machining Very mechanically intense design Hours of machining each day since the beginning of January Over 36 parts on each driven motor module Over 30 of these parts were machined or modified

Machining Machine shop staff was very helpful through out the entire process. Advanced machining techniques were introduced and explained by Rob Kraynik, Dave Hathaway and Steve Kosciol. Rob performed welding for several of the subassemblies

Machining The Brinkman CNC machining lab was needed on 3 parts. The need for precision led to the use of CNC Ease of mass production

Lessons Learned Price is usually a good measure of quality Modification of COTS parts may save money, but does add time to manufacturing Manufacturers models do not always match the actual product. Easy to add to a CAD model ≠ Easy to Machine!! (i.e. precise round plates)

Mechanical Design Modifications Extension of vertical driveshaft and addition of a supporting bearing to handle radial load exerted by spur gear Change from retaining rings to spacers, threaded axles, and washers Simplification of Yoke Sides Simplification of Motor Cage Change to smaller belt Additional washers to support available hardware

Verifying COTS Motor Performance Obtained dynamometer from Dave Krispinsky Fabricated coupling and mounting for motor to attach to dyno Applied several loading conditions to motor and took readings from dynamometer Motor speed was found using timing gun provided by Dr. Kempski

P07202: The H-Bridge First revision prototype on etch board PCB Cleaned copper is written over with sharpie marker. Then the holes for through-hole devices are tapped and drilled out After the necessary leads are soldered on the components can be placed and the revision of the board is ready for testing. Made use of simulated input signals and tested under loading conditions. After several revisions for the steering and drive motors, aftermarket H-Bridges were purchased due to budget constraints. The design schematics, simulations, and PCB Layout files were well documented for possible future use and mass production.

Power Board Originally design but not implemented. Included 6X 5V 1A lines, Battery Monitoring, Battery Indication, and Status Relay to P (Rev A Power Board Layout) No Longer Used

Motor Control Board Xilinx FPGA processor JTAG Programming CAN Communications Interfacing to H-Bridge Encoder Interpretation Built in Multi Stage Regulation Custom PCB design Board Temperature Sensing

P07202: Control and Communications Precise control over system allows for optimal efficiency designs High speed Power savings Fully parallel driven and steering control systems achieves true simultaneous operation CAN protocol is fully addressable and optimizes transmissions optimizes transmissions Significant potential for future functionality Incorporation of PIC soft core Generic I/O headers for interfacing with additional circuitry (e.g. watchdog) Easy to add additional devices over CAN

P07202: Error Protection and Failsafe Operation CAN protocol provides robust protection against noise. Errors of up to 5 consecutives bits can be identified and corrected Differential signal is more immune to noise Shielded, twisted pair cabling used to mitigate risk of interference State encoding ensures that any errors are safely caught operation is returned to idle mode Robust power up routines ensures integrity of system after booting Sophisticated I/O synchronization protects components from errors or potential damage Encoder inputs are properly measured H-bridge lines never activated simultaneously

P07202: CAN Transmission The Node that wins arbitration simply continues to transmit

P07202: Digital Encoders Drive Encoder Steer encoder The US Digital optical encoders were ordered to measure the speed of the modules using the measured RPM from the drive motor shafts. A different model US Digital optical encoder was used to measure the steering angle. An indexing function helped to read and convert the steering motor shaft’s RPM to an angular position. Pin-outs Optical Ring

P07202: Testing 3 Phases –Initial Baseline measurements Signals, Voltage levels –Semi-Integration Partial integration with Mechanical components To show components operate efficiently together –Full Integration (Prototype) Final measurements and stresses tested Reconfirmation of desired specifications Overall design assessed

P07202: Safety Several different fail-safe algorithms are coded into the FPGA for a variety of disturbances: –No wheel contact with ground –Liquid disturbances –Collisions –Communication connection loss Safety fuses are connected to the battery input to avoid burning out the motors and breaches of maximum speed. Current sensors are employed to ensure proper functionality of critical signal lines.

Electrical Budget Driver production cost (electrical) –$ PCB –$17.13 Chips –$22.29 H-bridges (COTS) –$ Encoders –$98.32 Cost of entire project –$ Prototype cost –$334

Mechanical Budget Driver prototype cost –$ Driver production cost –$ Idler prototype/production cost –$ Cost of entire project –$ Difference from original cost projection –$ All modules built

Looking Forward Total cost per driven module –$ Production cost per driven –$865.50

P07202: Questions ?