Micro Controller Based Coil Winding System

Project Goals

•Learn the fundamentals of microcontrollers– in particular the Phillips 89c51RD2.

•Understand the use of stepper motors.•Produce a useful device.

What is a Coil Winder?

• An inductive coil is an electromagnetic device and is comprised of tightly wound copper wire around a ferromagnetic core. A coil winder is a machine that automatically spools the copper wire onto the coil form precisely and accurately.

The Finished Coil

Three Critical Design Aspects

•How to turn the coil form.•How to position the wire during the

winding process.•How to control the winding process.

Motor Requirements

•Two motors will be used. One controls the turning of the coil form, the other positions the wire.

•There needs to be synchronization between the two motors.

Stepper Motors• A specific sequence of energized windings give

a very controlled motion.• Switches may be used to generate correct

sequence.

MOSFETS• The motors would ultimately be controlled by a

digital device.• A switch that can be driven by voltage levels

was required.• The MOSFET can be used as a switch, can be

operated by a micro controller, and in turn can control the stepper motors.

Coil Form Motor• Motor turns a spindle by way of a timing belt and gears.• To increase winding speed the motor was geared up 2 to 1.• Higher gear ratio did not improve speed.

Wire Positioning Motor

• Translating rotary motion in linear motion.

• Accounting for backlash.

Biggest Challenges in Designing the Positioning Motor Assembly

How to Control the Winding Process

• A Phillips 8051 derivative, the 89c51D2, was used.

• It has four 8-bit ports, 64K of memory and a UART for in-circuit programming.

• Overkill for this project – but useful for later applications in higher level EE courses.

How to Control the Winding Process

• To “home” is to get the position of an axis (the wire positioning assembly) to a location known by the controller.

• “Home” position was the starting position for the winding process.

• A proximity switch was used to guide the controller.

Building the Micro Controller Circuit

• The design was based on the UE Lego Board.

• The actual board was built from scratch.

• The main addition to the Lego Board’s original circuit design was the addition of a unipolar stepper motor driver capable of delivering the 3.5 amps of current required by each motor.

Constructing Using the WITS Method

• A rod to hold the spool of wire and legs for the machine were turned from one inch round aluminum stock.

• A simple tensioning device was fashioned from ¾ inch square aluminum tubing.

• A piece of shelving was machined to accommodate all of the mechanical and electrical elements.

• An ATX power supply from a long dead computer was modified to provide power for all of the electrical components.

turn on ready status LED

Programming the Micro Controller

“home” wire positioningassembly

wait for operator input move spindle motorIn desired direction

Coil on or off button pressed

turn off ready status LEDperform winding routine

Cycle start button pressed

move spindle motorIn desired directionwait for operator input

Coil on or off button pressed

Cycle start button pressed

poweron

Conclusion

• This project was a great learning experience.• It combined elements of programming, designing electrical circuits,

and designing mechanical devices.• The coil winding machine is a useful device that, although could be

improved, meets my current expectations.• More importantly, a great deal of insight was gained into

microcontrollers and stepper motors and how to implement them into a real world application.

• Lastly, my sincere appreciation to the UE faculty for their encouragement and support.