Tuesday, April 21, 2009

DC Servo motor Controller with Microcontroller Project

This is an experiment on the closed loop DC servomotor control system (SMC). It will able to be used for practical use with/without some modifications. The closed loop servo mechanism requires real-time servo operations, such as position control, velocity control and torque control. It will be suitable for implementation to any embedded 32 bit RISC processors as a middleware. In this project, these operations are processed with only a cheap 8 bit microcontroller.


Figure 1 shows the block diagram for SMC. This is built with only an AVR microcontroller and a PWM mode power amplifire. Whole of servo operation is processed by software implemented servo processor. Any analog component for servo operation is not used.Software

Figure 5 shows the servo operation for SMC. It is multiple feedback configuration which is most popular and fundamental servo mechanism at now. The servo operation which has multiple feedback, is called "Cascaded control". It is a kind of "Advanced servo mechanism". At the cascaded control, one or more control term whoes response is faster than major loop is chosen, and put it into the major control loop as minor control loop, the overall servo performance is increased.

DSPIC Servo motor Controller Project

This project was developed as an inexpensive way to drive small dc brushed motors as positioning servos for use on a desktop sized CNC machine. The board is interfaced to the PC through 2 pins of a parallel port. The drive signal on these pins is known as quadrature drive. The power stage consists of a power op amp driven in constant current mode. The internal PIC processor ( a 30f4012 from Microchip ) is programmed in C through the C30 compiler and the Microchip IDE. The servo loop parameters are programmed through a serial port connection and are saved in the dspic eeprom. Once set for a particular drive, they should not need to be changed.

Servo Control of a DC-Brush Motor
The PIC17C42 microcontroller is an excellent choice for
cost-effective servo control in embedded applications.
Due to its Harvard architecture and RISC features, the
PIC17C42 offers excellent computation speed needed
for real-time closed loop servo control. This application
note examines the use of the PIC17C42 as a DC brush
motor servo controller. It is shown that a PID (Proportional,
Integral, Differential) control calculation can be
performed in less than 200 us (@16 MHz) allowing control
loop sample times in the 2 kHz range. Encoder rates
up to 3 MHz are easily handled by the PIC17C42's high
speed peripherals. Further, the on-chip peripherals allow
an absolute minimum cost system to be constructed.

The servo system discussed in this application note
uses a PIC17C42 microcontroller, a programmable
logic device (PLD), and a single-chip H-bridge driver.
Such a system might be used as a positioning controller
in a printer, plotter, or scanner. The low cost of implementing
a servo control system using the PIC17C42
allows this system to compete favorably with stepper
motor systems by offering a number of advantages:
• Increased Acceleration, Velocity
• Improved Efficiency
• Reduced Audible Noise
• True Disturbance Rejection

more pdf

PICmicro DC Motor Control Tips ‘n Tricks
Every motor control circuit can be divided into the
drive electronics and the controlling software.
These two pieces can be fairly simple or extremely
complicated depending upon the motor type, the
system requirements and the hardware/software
complexity trade-off. Generally, higher
performance systems require more complicated
hardware. This booklet describes many basic
circuits and software building blocks commonly
used to control motors. The booklet also provides
references to Microchip application notes that
describe many motor control concepts in more

TIP #1: Brushed DC Motor Drive Circuits ................2
TIP #2: Brushless DC Motor Drive Circuits..............5
TIP #3: Stepper Motor Drive Circuits .......................9
TIP #4: Drive Software...........................................13
TIP #5: Writing a PWM Value to the CCP Registers
with a Mid-range PICmicro® MCU.............17
TIP #6: Current Sensing ........................................19
TIP #7: Position/Speed Sensing ............................23
more pdf

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