Electronic Engineering Final Year Project

Switched-Controlled Turntable

Name: Dean McDonnell

Supervisor: Dr. Maeve Duffy

Electronic Engineering Final Year Project

Objective of Project

1. To Design and Build a Switch-Controlled Turntable

2. Controlled through an infra-red remote control

3. Full 360 degree turn, bi-directionally

4. Stepped in 90 degree angles

5. Addition to project includes a second motor

6. Design Issues: Fit under assortment of beds and Portability

Electronic Engineering Final Year Project

Previous Design

• Another version designed and built in the USA

• Two students from University at Chapel Hill

• Use by children with severe and profound disabilities at Lake Wood Elementary School

• Children were unable to retrieve toys independently

• They could not choose between items when presented multiple options

• Table required auditory, visual and tactile feedback

• Needed to fit the needs of a variety of children

• Named “The Lazy Susan”

Building of Previous Design

Electronic Engineering Final Year Project

Previous Design

• Advantages were immediately noticed

• Allows access to multiple toys from a single location

• Consists of partitions used to segregate the toys from one another

• LED’s and spoken messages are also integrated

• Provide visual stimulation and auditory feedback

• Very important for teachers, therapists and children

Electronic Engineering Final Year Project

Operation of Previous Design

Electronic Engineering Final Year Project

Electronic Engineering Final Year Project

Initial Step

Infra-Red ExecutionInfra-Red Execution Infra-Red Receiver Infra-Red Receiver

Microprocessor Microprocessor

Motor Drive Motor Drive

Motor Motor Table

Finding the Motor

• Stepper Motors were a must

• Datasheets of different motors researched

• Tests carried out on different motors

• Results had to show that motor is capable of rotating a mass of 5 kilograms

• Also needed to be cost effective

• Rotate the mass within approx. 7 seconds without exceeding 12 volts

• Minimal stopping and starting times

Electronic Engineering Final Year Project

Testing the Motor

• Initial test involved having no load

• Select few motors were advanced to second test

• Second test involved load of 5kg

• Load tied onto coupling that was placed on motor

• Results achieved determined the appropriate motor

• Chosen Motor was the MFA COMO DRILLS 919D SERIES Single Ratio Gearbox

Electronic Engineering Final Year Project

Motor Test Results

Electronic Engineering Final Year Project

Finding the Motor Controller

Electronic Engineering Final Year Project

• H-bridge was chosen for the task

• Used to control the polarity of the motor

• Used to turn the motor bi-directionally

• Also used to “brake” the motor

Testing the Motor Controller

Electronic Engineering Final Year Project

• The controller placed into the breadboard.

• Voltage supply added

• Motor attached to breadboard

• Motor turned bi-directionally as well as “braking” when needed

• Oscilloscope was used to observe wave patterns

H-bridge Characteristics

Electronic Engineering Final Year Project

• L293 used for this project

• Two separate sides - Only one side needed

• Pin1 – Switch Enable

• Pin2 – High Pulse (Oscilloscope Channel 1 Connected)

• Pin3 – High Output to Motor (Oscilloscope Channel 2 Connected)

• Pin4 – Ground Also Connected to Pulse Ground

• Pin5 – Ground

• Pin6 – Low Output to Motor

• Pin7 – Low Pulse

• Pin8 – Voltage In (Connected to Pin16)

Motor Controller Results

Electronic Engineering Final Year Project

Shows the stepping changes on the H-bridge

Testing the Microcontroller

Electronic Engineering Final Year Project

• 8051 ADuC831 used for this project

• A program is needed in order to test the 8051

• Programmed in C

• After weeks of testing, the program finally resulted in direct communication between the computer and the 8051

Microcontroller Results

Electronic Engineering Final Year Project

• Direct communication between the computer and the 8051

• LED flashing indicates this

• Hyper-terminal reads in the character ‘1’ from the 8051 (seen in next slide)

Microcontroller Results

Electronic Engineering Final Year Project

Addition to Microcontroller Results

Electronic Engineering Final Year Project

• Addition to the program has been achieved

• This addition involves the motion of the motor through the H-bridge

• The motor can be controlled to turn clockwise as well as anti-clockwise

• The motor can also be stopped or “braked” by the H-bridge

Next Steps

Electronic Engineering Final Year Project

• Next steps are based around the infra red user device

• This involves the building of the infra-red receiver

• After that, the project will lead on to getting the second motor

• This second motor will control the upwards/downwards motion of the table

• Once this motor is coded, the physical designing of the table will follow

Questions?

Electronic Engineering Final Year Project