Buggy Following Magnetic Strip

This is a video preview of our buggy following the Magnetic Strip

LED change

With the presentation looming our utter most concern is for the buggy to complete the course and this has led to some inspired last minute changes. So far throughout testing 2 red LEDs were being used with the intention of carrying these on to the presentation but unfortunately or rather fortunatelywe have discovered that we are these are causing calibration problems.

This is due to the red LED not providing enough constant elumination to the LDRs so as to maintain the same binary analogue values. This has led us to test and switch to using to white LEDs even though they are more costly. This is simplly because the illumination they give is far much superior that what we have been testing so far and therfore this should boost our line following chances and at the same time reduce the need for constant re-calibration.

Circuitry Testing

This is full circuitry connected to test the code. this is the full set up of our buggy before being assembled to the chassis and using variable resistors as part of the analogue input. Just for testing sake we first used two LEDs as outputs instead of the driver board and two motor set up. This helped us test the code without having fully assembled the buggy.

We have decided to stick to the breadboard for our circuitry instead of other options such as circuit boards or smaller bread boards and this will help us keep the costs low for our buggy. This therefore means we will have to model the chassis around the full bread board.

After tests the circuitry worked and therefore the next step was to connected it up to the motor board and motors and again this worked beautifully using simple code to test the connections, meaning we are ready for assembly and programming the code into the chip.

Cicuitry

This is the circuitry used to run our buggy. Using an analogue input of LDRs connected via two 4.7k resistors instead of variable resistors so as to give us a more steady analogue value. This is then outputted to two motors connected through the motor driver board so as to control the direction for our buggy. Two LEDs are also used connected in series as outputs so as to give illumination to the LDRs.

Care has to be taken when assembling so as to keep away from frying the delicate chips or short circuiting.

Choosing Input Sensing Method

As the objective of the project is for the buggy to follow the line, we will be using 1 of 2 inputs to send a signal to the motors when the is a change in light intensity. The choice we have is between using LDRs to send a signal when light intensity changes or Magnetic Reed Switches to send a signal when the magnetic strip is detected.

To help us make the best choice we set up a simple circuit outputting the LDR/Reed Switch to a simple LED to represent our motor.

Having carried out this test it was easy to make the decision that LDRs would be used as our input. We decided to use 2 LDRs which will be used in series with LEDs to send an input into the chip when the magnetic strip is sensed.