Critical Design Review

1. Critical Design Review BoneCrusher Automation Floor Art Super Transcriber (F.A.S.T) NiketSheth Chris Karman Erik Scherbenske Peter van der Hoop

2. Objectives • Build a robot to reproduce shapes, text or follow user input paths. • Robot will use markers to create drawings on the floor. • Scalable drawings depending on floor size.

3. User Interface • Tethered Control using: • Joystick • Keyboard • Pre-Encoded Instructions • Touchpad • Wireless control should eventually replace tethered line

4. Modified Project Goals • Milestone 1 • Moving robot that can be controlled with directional inputs via USB input • Milestone 2 • Robot can reproduce shapes and text given a user input. • Expo++ • Robot is wireless, can use multiple marker colors, has collision and boundary detection sensors, and can follow touch pad input drawings.

5. High Level Block Diagram Marker Input CPU (MSP430) Motor Drivers (L297, L298A) Sensors

6. Low Level Block Diagram

7. Movement • Robot moves with two Sure Step stepper motors that take inputs from DRV8412 motor drivers • The DRV8412 is a high performance integrated dual full bridge motor driver • Takes 4 out-of-phase inputs to drive the motors • We have switched from the DRV8412 to the L298N and L297 • L297 generates 4 outputs from a single clock input to drive the motors (connected to L298N)

8. Stepper Motor: DRV8412 • Operating Supply Voltage up to 50V • 3A max current output • Operating frequency up to 500kHz • Integrated self-protection circuits (under voltage, over temperature, overload, short circuit) • No external schottky diodes required • Takes four off-phase step functions as input

9. MSP430 to DRV8412

10. Substitutes: L298N and L297 • Much simpler two phase bipolar stepper motor driver than the DRV8412 • Takes only one step input • 46V, 4A max • Over temperature protection • High noise immunity

11. L298N and L297 Circuit Diagram MSP430

12. Sure Step Stepper Motors • NEMA-17 • 1.8 degrees per full step • Half-Step Capability • Holding current up to 1.7 A • Input • 4 out-of-phase step functions • 1.6 ohms

13. Drawing • Use a stepper motor to rotate markers into place (PWM). • MSP430 provides the path to draw • Multiple color control through the motor PWM.

14. Marker Stepper Motor • Controls rotation of marker wheel • Spring controlled pressure on markers • Color change capabilities • Uses the same motor drivers and stepper motors as the wheels Rotate Pen Down/Up Motor

15. CPU • MSP430f1232 • 3 PWMs • Multiple digital I/O • UART Control • DAC • 8 MHz

16. MSP430F1232 Motor Reset Motor 3 Enable 5V Rail Motor 2 Enable Motor 1 Enable Motor 3 PWM Motor 2 PWM Reset Button Motor 1 PWM Motor 3 Direction Collision Detection Motor 2 Direction Collision Detection Motor 1 Direction Collision Detection PC Connection Collision Detection PC Connection

17. Uses of MSP430 • Motor Control • 3 PWMs (Square Waves) – 3 Motors • Speed – Period of waves • Distance – Duration of signal • Marker Control • Controlled by Marker Wheel attached with Stepper Motor • Signal will enable the wheel to rotate until marker in DOWN position.

18. CPU & Motor Control Communication • Opto-isolators • Separate the MSP430 from L298N and L297 in case of mishaps. • May need to add transistors for current boosts. • MSP430 might not be able to apply enough current to the opto-isolators • Control of the Direction and Speed will be determined by code on MSP430

19. Software Flow Chart

20. Sensor Controls • Collision Detection • Bumpers that detect collision and send data to CPU • Infrared that detect objects in path before collision • Boundary Detection • Detect predefined physical boundary • Infrared (black line surrounding “canvas”) • Using MAX3100, MAX3120 infrared drivers. • Software boundary • Max distance allowed for travel from initial starting point • Turn OFF or correct motion when the sensors detects a problem.

21. Infrared Sensor: MAX3120

22. Infrared Sensor: MAX3120 • 3 to 5.5V operating voltage. • 1 CM to 1 M detection range. • High accuracy (built-in narrow band pass filter). • Compatible with MAX3100 (IR to UART Data Link). • Schmitt Trigger input/output operation.

23. Power Management • Power Control Board • Provide 50V for the stepper motor, 7V for the logic circuitry (motor driver), and 2V for the MSP430 CPU chip. • Isolation circuit using opto-isolators MAX232IN for providing current to motor. • Power monitoring and reporting controlled by MSP430. • Conservation of power by shutting down components not being used by controlling the signal to the enable pin in the motor driver. • Rechargeable battery.

24. Updated Schedule

25. Updated Division of Labor

26. Updated Budget

27. Risks and Recovery • Signal/Power Noise • Opto-Isolators, separate regulators purchased • Motor Accuracy • Loose Contacts between wheel and ground – Slowly build up the speed to avoid loose contact. • Inaccurate stepping by motor – High current keeps steps accurate • Power management surges and spikes • Opto-Isolators • Lose communication with robot • Range - Software controlled Power OFF • Loose wiring – Effective Build Up • Uncertainty in learning curve • Uncertainty in parts availability and delivery • Unfamiliar technology

28. QUESTIONS????