It is a cart run on the black line, but not as same as usual line followers. This have two Stepper motors to drive front wheels(Turn left and right directions) and rear wheels separately. Their is three IR sensors to recognize the black line and white background. No more words are needed, just look at bellow videos. You can be found all PCBs, mikroC code and each and every resources what I used for this project.
Total unit can be divided in to seven main parts for easy reference,
1.MCU18F4520 .
The comparator use to increase the sensitivity of path recognize IR sensor. Limit sensors do not work without comparator.
Read more about comparator
I have to use more comparators when increasing the number of loop back link, so I add two operational amplifiers called LM 379 (DATA SHEET).
Remote Controller (RC)
Further I could add remote controller which taken out from RC toy car, then I had to add below PCB to isolate front wheel motion sensors.
Download PCB Diagram
7. Power PCB
Power supply system also had to change when changing motors. Two separate LM7805 regulators are used to feed controller MCU and IR sensors, one LM7809 regulator is used to feed front wheel driver motor and one LM7812 regulator is used to feed rear wheels independently. So I believe initial high current drawn of motors and noises due to moving Electromagnetic coils will not affect on the controllable system. This will provide strong stability on response from loop back sensors.
:::::::::::watch the videos::::::::::::::-
- Two Possible modes, Remote Control (RC) and Line Follower (LF).
- Auto recognise Black lines (Road) when run in LF mode.
- Auto Stop at the end of the road.
- Move back to the road if jump over the road.
- Interchangeable between two modes (RC/LF) using the manual switch.
- Lights up if environment light decrease.
Total unit can be divided in to seven main parts for easy reference,
1.MCU18F4520 .
It is a PIC microcontroller from Microchip with 40 pins, 4 Ports and little advance than 16F877A. However it is possible to use 16F877A but I here utilize above IC because I haven't any other at this moment.
Data Sheet
2. Control Board
It's is a main PCB which control the line follower. These PCB is made by toner transfer
Circuit Diagram can be download
3. Front Twisting Stepper motor.
Data Sheet
2. Control Board
It's is a main PCB which control the line follower. These PCB is made by toner transfer
Circuit Diagram can be download
3. Front Twisting Stepper motor.
It is a stepper motor with a set of gear wheels which taken out from old machine, however I still suffering how to speed up it until reach sufficient twisting speed is reached. It's drown by PORTD.4~7.
Front wheels need to move left and right quickly to get smooth and fast motion but stepper motor will not give fast motion. I could reduce up to 10ms for single step but overall speed not in the required speed range. So I had to change front wheels as below with DC motor.
It is a another stepper motor geared by my self which also taken from a old machine. I used halfdrive for both stepper motors and rear motor is droved by PORD.0~3 pin outs.
Limit Sensors.
Unfortunately Stepper motor wasn't work with my cart. It drive very slowly and it can't build sufficient torque to rotate the rear wheels. So I changed stepper motor to DC motor to achieve enough speed with sufficient torque to drive rear wheels.
H-Bridge
H bridge is used to drive DC motor for both direction (clockwise and anti-clockwise ) with two signal (A,B), I took out two IC from old photocopy machines.
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| Principle of H-Bridge Driver |
IC DATA Sheet
Limit Sensors.
I have to stop front motor at certain point when rotating left and right to eliminate break out of mechanical motion system , so here what I used is limit sensors.
5.Path recognizing IR sensors.
Three IR proximity sensors which used to recognize papers in old photocopy machine were utilized to identify the black line of the path. This sensors give output (+5V) in the absence of a the object and (0V) in the presence of a object. If sensor is in black line it recognize as absence and white line as percent. A middle sensor always in the black line and rest of two in the while line.
The comparator use to increase the sensitivity of path recognize IR sensor. Limit sensors do not work without comparator.
Read more about comparator
 |
| Comparator |
I have to use more comparators when increasing the number of loop back link, so I add two operational amplifiers called LM 379 (DATA SHEET).
Remote Controller (RC)
Further I could add remote controller which taken out from RC toy car, then I had to add below PCB to isolate front wheel motion sensors.
Download PCB Diagram
7. Power PCB
Power PCB used to energize the control board with +5V and ,Stepper motors with +12V
Power supply system also had to change when changing motors. Two separate LM7805 regulators are used to feed controller MCU and IR sensors, one LM7809 regulator is used to feed front wheel driver motor and one LM7812 regulator is used to feed rear wheels independently. So I believe initial high current drawn of motors and noises due to moving Electromagnetic coils will not affect on the controllable system. This will provide strong stability on response from loop back sensors.
:::::::::::watch the videos::::::::::::::-
Green Colour First Update..!
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