Design Proposal

Problem Overview

The project that is being undertaken is to design and fabricate a motor controller that can operate two motors that will be mounted on a vehicle. The one motor will act as a drive motor and the other motor will be used for either steering or stability control. The controller will have to be able to independently control the motors and move the vehicle in a pre-programmed manner based on the final designs specifications. The planned way of controlling the motor is to use pulse width modulation that will control the amount of voltage sent to the motor without overheating the motors.

Design Constraints

The project will be working on an approximately 1:25 scale of an actual size vehicle.  That means our car will be approximately 7 inches in length and approximately 4 inches wide.  The scale of the project means that the project must remain light enough so that the load placed on the motor does not exceed its maximum capacity. Some parts, such as the motors, batteries, transmitters, and micro controller, will be commercially procured and incorporated into the system. The rest will be fabricated using a 3-D printer and rapid prototype machine, or machined to specifications. The design will only be used in short range operations so that testing can be accomplished without needing governmental approval.

Pre-existing solutions

There are many examples of motor controllers on this small scale. Most radio controlled vehicles use a radio controlled motor controller with a receiver on the vehicle to move the motors and a way to control the power output to the motors such as varying resistance or voltage regulation. The device we will use will send pulses of power to the motors that will come in phases and the magnitude of the pulses will control the speed of the motor.

Design Goal

The design goal is to create a controller that can control both motors simultaneously using either a remote control or radio control device. The system will use a pulse width generator to provide an amount of power over a specified time. The speed will be controlled by the length of the pulse and frequency. The final vehicle has not been decided on as of yet but will be either a car or a helicopter design if the time constraints allow for it.

Project Deliverables

The first deliverable of this project is to create the controller using a breadboard, power source, and resistors, and connecting it to a motor to verify it can operate as designed. Once initial setup and testing is completed, the next phase will be to plan the vehicle according to amount of time available to complete the project. The next deliverable will be the assembly of the vehicle and initial setup and testing. The final deliverable will be the final testing and demonstration of the design to the class.

Project Schedule

The remaining projected schedule is as follows:

Week 3. Assembly of the controller and initial testing.

Week 4. Continue testing of controller and begin to plan vehicle

Week 5. Finalize initial testing and begin to design vehicle.

Week 6. Initial assembly of vehicle.

Week 7. Testing and redesign as necessary.

Week 8. Finalize testing.

Week 9. Final test and initial demonstration

Week 10. Demonstration of design.

Projected Budget

The projected budget is between $40 and $60. The budget depends on our ability to fabricate as many parts as possible for the vehicle and what the final vehicle will be.


*Update*

The final vehicle design that was agreed on is a car that will be remote controlled with 2 motors.  one will drive the main wheels while the other will control steering.  We were able to salvage some parts from an old PC.  The parts we are using are a LED to show that the board is powered up, the motor that controlled the laser position of a CD drive, 2 potentiometers, and some ribbon cables we can use as extra jumper wires.  The IC chip we chose is Texas Instruments SN754410NE 4 Channel Integrated Controller.  As of 4/27/2012, all parts are in and initial assembly of the circuit board has been started.



*Update # 2*

For ease of design and under time contrraints we decided to go with Lego NXT motors and pieces for the chassis and will use the ICL8038 waveform generatr chip.  The system will be powered by a 9V 1 amp power supply which can easily power the NXT motors but renders all other motors and parts previously used unable to be used as they require lower power inputs.