6 Motor circuit Stepper motor controllers have full/half step mode for different accuracy, as well as a range of varying currents for different speeds. Software control can converge smoothly on a target based on how many steps away. Motors very noisy, inductors have huge voltage spikes when switching current. Steppers will be on a different power circuit than microcontroller.
7 Stepper Motor Specifications Limited by switching speeds of hardware controllers Can sweep 30 degrees / step in full step mode,15 degrees / step in half step mode. Travel full field of view ~1 second. Torque curve sufficient for turret.
8 Digital Signal Processor: Analog Blackfin or Tigershark DSP Motorola 56307 – used in DSP lab PC104 Pentium processor
9 PIC microcontroller Pros: –Very easy to use. Cons: –Everything done for us already.
10 MC68HC11 Specifications: 8-channel A/D converter (may use external chip) Asynchronous serial communications interface (SCI) Separate synchronous serial peripherals interface (SPI) 2 8-bit accumulators (A & B), which can act as a single 16-bit accumulator (D)
11 Specifications continued: 3 input capture lines, 5 output capture lines 2 16 bit index registers 1 stack pointer
16 Optional use of FPGA: Stepper motor controls Nintendo controller logic Interrupt servicing
17 On Board Demonstrations: The controller will have a control mode that can be enabled to put the laser into demo mode. 3 separate preprogrammed paths: Circle, Square, and Infinity.
18 The Motor System Problems Accuracy Control Position / Calibration
19 Accuracy: Bipolar stepper motors 3.8 degree and 1.9 degree Industry Standard H-Bridge controller required Half step implementation realization
20 H-Bridge Controllers 1 pin Step control Pulse width for full or half step 2 pin Phase control Direction of motor 2 pin Current control Handles up to 1.5 amps Only need 0.5 to 0.75 amps
21 Positioning Manual control for calibration Uses NES game pad Memory for position reference Non volatile memory too slow Shaft encoders just too inaccurate
22 Software Task Perform by software in our design
23 Small Software state machine for the four modes Manual or Game Pad mode Demo mode Tracking mode Calibration mode The current mode will be displayed on the LCD screen
24 Control of the two RS-232 interfaces Serial interface to the PC104+ to receive XY coordinates for tracking Serial Interface to monitor computer, this is used by the BUFFALO monitor program
25 Human Interface Devices LCD, it will be used for most of the output to the user Serial Terminal, information can be transmitted to the terminal for debugging purposes LED lights, Sound, etc.
26 Monitor program The Motorola BUFFALO monitor program located locally on EEPROM
27 BUFFALO Basic Commands CommandDescription BF Block fill memory with data LOAD Download (S-records) MD [ [ ]]Dump memory to terminal MM [ ]Memory modify HELPDisplay monitor commands
28 Goals for the project Minimum: Implement one two-dimensional laser turret controlled by one Game Pad. Goal: Implement one two-dimensional laser turret controlled either by Demo Mode, Tracking system or Game Pad. Extension: Implement two two-dimensional laser turrets controlled by Demo Mode, Tracking System or two Game Pads. Maximum: Replace the laser by a more extravagant device, i.e. dart gun, BB gun, missile, etc.)
29 Objective Timeline CDR: Main Board Schematics Obtain Main board parts Motor board schematics Assemble microcontroller board Get processor running Milestone 1: Obtain Motor Board Assemble Motor board Finish and test microcontroller hardware Implement Game Pad interface
30 Objective Timeline (Cont) Milestone 2: Monitor program running Implement interface with motors Real Time Embedded system PC104+ module Expo: Run Demo modes for the laser Receive XY and control laser Calibrate stepper motors for tracking