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Motor Control. For the Sieg Defense Platform by Michael Dougherty Gary Look Gene Ma Reviewed by Ngochan Nguyen, Duy Le, Valdis Riekstins. Description. - PowerPoint PPT Presentation
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Motor Control
For the Sieg Defense Platform
by
Michael Dougherty
Gary Look
Gene Ma
Reviewed by Ngochan Nguyen, Duy Le, Valdis Riekstins
Description
• Once given a new x-value for the x-coordinate motor, this control is responsible for providing the stepper motor driver chip with the needed signals to move the stepper motor to this position.
• There is another control corresponding to the motor for the y-coordinate.
• There is a slight difference in scaling between the x and y controls.
Stepper Motor Driver Chip
• The stepper motors require 0.5 mA to be driven, which the XESS board cannot provide.
• This chip receives signals from the motor control module, so that it can drive the motor.
• The chip drives the motor at 5 V.
Stepper Motor Driver Chip Inputs
• CLK (pin 7) - Generated by the motor control module
• CW/CCW (pin 10) - When low, the stepper motor is driven clockwise (right), and when high, the motor is driven counter-clockwise (left)
FPGA Signals
Inputs• TOUCHX[8:0] - x-coordinate to move the motor to
• RST - reset the x-coordinate motor to 256 (the x-coordinate range is 0 to 512)
• CLK - clock signal from the FPGA
Outputs• MotorX[15:0] - current x-coordinate of the motor
• MotorCon[1:0] - outputs to the Stepper Motor Chip (MotorCon[1] is CW/CCW, MotorCon[0] is CLK
How It Works
• The motor control keeps track of the current coordinates and also outputs them, so that a crosshair can be displayed on the screen.
• If the input x-coordinate is less than the current one, the motor control tells the driver chip to move the motor counter-clockwise (left), and for greater than, it tells it to move the motor clockwise (right).
• There is a mapping between the number of pixels between 2 points on the screen, and the amount of stepper motor movement for the corresponding distance.
footstepsfeet
steps/10
5
deg90
deg360
200
Scaling Factor
• It takes 200 steps to move the motor 360 degrees
• For example, if there are 5 feet between 2 points, and it takes 90 degrees of movement to go between them
• Since it takes a lot of time (in terms of clock cycles) for the stepper motor to physically move, a one million clock cycle delay (0.042 s) is introduced before the motor is told to move again.
• MotorCon[0] is connected to the CLK pin of the driver chip. Every time the chip sees a positive edge, it moves the motor half a step in the direction given by MotorCon[1].
Good Points
• The motor control will still work correctly when another coordinate is given before the motor has reached the previous one
• The delay between stepper motor signals ensures the motor has enough time to reach the correct coordinate
May Need Work
• The scaling factor may need to be adjusted for certain points in the screen/motor range
• Try to shorten the delay between motor signals as much as possible