This line follower robot use the following module:

• Proximity sensor: 8 pcs of phototransistors
• Microcontroller: ATMega16
• Motor driver: L298 module
• Programming language: C

Download the document of this line follower robot tutorial HERE

This tutorial created by:
Priyank Patil
Department of Information Technology
K. J. Somaiya College of Engineering
Mumbai, India

Lecture 2. Technologies in Robots

Lecture 3. Industrial Robots

Lecture 4. Industrial Manipulators and its Kinematics

Lecture 5. Parallel Manipulators

Lecture 6. Grippers Manipulators

Lecture 7. Electric Actuators

Lecture 8. Actuators – Electric, Hydraulic, Pneumatic

Lecture 9. Internal State Sensors

Lecture 10. Internal State Sensors

Lecture 11. External State Sensors

Lecture 12. Trajectory planning

Lecture 13. Trajectory Planning

Lecture 14. Trajectory Planning

Lecture 15. Trajectory Planning

Lecture 16. Trajectory Planning

Lecture 17. Trajectory Planning

Lecture 18. Trajectory Planning

Lecture 19. Trajectory Planning

Lecture 20. Forward Position Control

Lecture 21. Inverse Problem

Lecture 22. Velocity Analysis

Lecture 23. Velocity Analysis

Lecture 24. Dynamic Analysis

Lecture 25. Image Processing

Lecture 26. Image Processing

Lecture 27. Image Processing

Lecture 28. Image Processing

Lecture 29. Image Processing

Lecture 30. Image Processing

Lecture 31. Robot Dynamics and Control

Lecture 32. Robot Dynamics and Control

Lecture 33. Robot Dynamics and Control

Lecture 34. Robot Dynamics and Control

Lecture 35. Robot Dynamics and Control

Lecture 36. Robot Dynamics and Control

Lecture 37. Futuristic Topics in Robotics

Lecture 38.

Lecture 39.

Lecture 40. Futuristic Topics in Robotics

I’ve collected some schematic diagrams of sound activation as follow:

Sound Activation schematic 1

Sound Activation schematic 2

Sound Activation schematic 3

Sound Activation 4 schematic

Sound Activation schematic 5

You may see the video here.

This line follower robot is very small and simple. This robot is running fast and follow the line very smoothly.

Mechanics

All mechanical and electrical parts are mounted on a proto board, and it also constitutes the chasis.

The line following robot is upheld in three points of two driving wheels and a free wheel. The driving wheels are made with a 7 mm dia ball bearing and a rubber tire. The free wheel is a 5 mm dia ball bearing attached loosely. To drive driving wheels, two tiny vibration motors that used for cellular phone, pager or any mobile equipment are used. Its shaft is pressed onto the tire with a spring plate, the output torque is transferred to the wheels.

The steearing mechanism is realized in differential drive that steear the robot by difference in rotation speed between the left wheel and the right wheel. It does not require any additional actuator, only controling the wheel speed will do.

Line detector and Photo reflector

To detect a line to be followed, most contestants are using two or more number of poto-reflectors. Its output current that proportional to reflection rate of the floor is converted to voltage with a resister and tested it if the line is detected or not. However the threshold voltage cannot be fixed to any level because optical current by ambent light is added to the output current like the image shown right.

Most photo-detecting modules for industrial use are using modurated light to avoid interference by the ambient light. The detected signal is filtered with a band pass filter and disused signals are filtered out. Therefore only the modurated signal from the light emitter can be detected. Of course the detector must not be saturated by ambient light, this is effective when the detector is working in linear region.

In this project, pulsed light is used to cancel ambient light. This is suitable for arraied sensors that scanned in sequence to avoid interference from next sensor. The microcontroller starts to scan the sensor status, sample an output voltage, turn on LED and sample again the output voltage. The difference between the two samples is the optical current by LED, output voltage by the ambient light is canceled. The other sensors are also scanned the same avobe in sequence.

Line Detection Signal Processing

Right image shows the actual line posisiton vs detected line position in center value of 640. The microcontroller scans six sensors and calcurates the line position by output ratio of two sensors near the line. Thus the line position can be detected lineary with only six sensors. All the sensor outputs are captured as analog value that proportioning to reflection ratio, and the sensitivity have variety between each one of them. In this system, to remove the variations from the outputs, calibration parameters for each sensor can be held into non-volatile memory. This can be done with online mode. The microcontroler enters the online mode when an ISP cable is attached, and it can be controlled with a terminal program in serial format of N81 38.4kbps. S1 command monitors sensor values, and S2 command calibrates variation of sensor gain on the reference surface (white paper). The ATmega8 must be set to 8MHz internal osc.

Tracking Control

The line position is compeared to the center value to be tracked, the position error is processed with Proportional/Integral/Diffence filters to generate steering command. The line folloing robot tracks the line in PID control that the most popular argolithm for servo control.

The proportional term is the commom process in the servo system. It is only a gain amplifire without time dependent process. The differencial term is applied in order to improve the responce to disturbance, and it also compensate phase lag at the controled object. The D term will be required in most case to stabilize tracking motion. The I term is not used in this project from following resons. The I term that boosts DC gain is applied in order to remove left offset error, however, it often decrease servo stability due to its phase lag. The line following operation can ignore such tracking offset so that the I term is not required.

When any line sensing error has occured for a time due to getting out of line or end of line, the motors are stopped and the microcontroller enters sleep state of zero power consumption.
Notes:

• Development diary [Ja]
• Circuit diagram
• Firmware May 23, 2004
• Following motion with only P control
  This is a video file of line following motion with only P control. The servo system oscllated.
• Following motion with P and D controls
  Adding D control could improve the servo stability. The robot follows the line correctly. Therefore the servo parameter must be optimized for mechanical characterristics to improve the tracking stability.

Ho it can be..?
There are many robot tutorial has been written and published through blog or web. I found interesting robot tutorial from this web. The author said that he build the robot just in 2 hours, you also can see the video there… just visit the web…

You can download the tutorial here

Microcontroller : Atmel ATMega8535
Sensor: 6 photodioda sensor
Motor driver : L298 dual driver (up to 1A of electric current)

Download the full tutorial include schematic diagram and program code ( C language ):
Download link

Download ping parallax ultrasonic distance sensor datasheet, schematic and program code sample:
» Download Link

Many fire fighting robot competition in the world with diffrerent mission but have similiar field…
Here some useful reports of fire fighting robot project.:

» fire_fighting_robot_project1.pdf
» Zephyr_Final_Report_Fire_Fighting_Robot.pdf
» Multiple_Robot_Path_Planning_Strategies_for_Bush_Fire_Fighting.pdf
» navigation_robot_tutorial.pdf
» Firebot.pdf
» FireFightingRobot.pdf
» Fire_Fighting_Neural_Robot.pdf
» MQP_Fire_Fighting_Robot_Report.pdf
» Fire_Fighting_Robot_Tutorial.rar

Introduction

One of my student has made a disgraceful robot that used two stepper motors and with a simple IR sensor. Yes, above picture is what I’m talking. Without battery carrying, a little bit torque of the stepper and misalignment of driving shaft, makes it crawling not walking, but first demo, showed quite impressive to me. He said he wrote a couple of program lines using C, his robot can track the black tape. I feel delighted his intention and endeavor. I thought, ” he borrowed me DS5000, expensive one, a soft uController with internal bootloader, why shouldn’t try with our learning board C-52 Evaluation Board instead”. Another one, told me the same day “I found the L293 Push/Pull Four Channel Driver at Ban-Moah, it costs 1.5 US$ “. I’ve been searching this chip for a year.

The MiniBoard, a Motorola 68HC11 Robot Controller board designed by Fred G. Martin, also uses this driver. The day after, I then decided to prepare the page describing how to use C-52 EVB as a robot controller board. I asked my student for competition, build yourselves robot that can track the black tape. Prize for the winner is 100 US$, with a bit condition that the winner must pay for a big party at Soi Jinda’s Somtum (Papaya Salad) shop. And one of the competitor is me. I thought the rule should be conceived roughly by students and technically by me. The picture on that day will put here soon.C-52 EVB resources

Beforehand, let look at available resources of C-52 EVB for robot experiments.

DC Motor Driver

Basic circuit of using L293 forms an H-Bridge Driver is shown in Figure 1. As shown for such inductive load as DC motor, external diodes for suppressing back EMF must be connected. The MiniBoard uses L293D instead, the L293D has internal diodes, however providing a bit less driving capacity, i.e., 600mA @4.5V-36V. From the truth table, we see that direction of the motor can control by pin C and D. VINH enable/disable power to the motor, thus for speed regulation, we then use this pin for PWM signaling. See details, L293.pdf data sheet.

Figure 1: Basic circuit of L293 forms H-Bridge Driver

A circuit connecting C-52 P1 to L293 driver chip is shown in Figure 2. As shown Enable pin 1 connected to P1.0 is for PWM signaling. We use additional inverter at pin7 and pin 15 to provide proper logic for easy directional control. Please note that pin 4,5,12,13 are tied to ground and if heat sinking needed, one method is to make a large area of PCB or soldering it with a metal sheet, say.

Figure 2: Connecting C-52 EVB P1.4-P1.7 to L293. External diodes must be connected for L293(not shown in circuit diagram).

My latest design put additional inverter for PWM signal at pin 1 and pin 9 to prevent full power delivering to DC motors when resetting the 89C52(i.e., all bits of P1 is logic high). Check the logic of PWM pins for another microcontrollers.

Line Tracking Sensor (I have to KUK)
Since there’s no ADC for 89C52 chip, each competitor may build their own Line Tracking Sensor, some may use LM339 QUAD comparator with IR transmitter and receiver, some may use LDR as described in Line Follower Robot . With an external comparator, it may not necessary to have ADC, but with LDR, we need external ADC. ” Having additional ADC for 89C52 would be better”, I thought. How can we provide ADC for 89C52 with a cheap method? I chose PIC16C711 with 4-channel ADC, and 7-pin input port. Interfacing to 89C52 is done with simple PISO protocol by using RB0 for SCLK and RA4 for SDA.The code for such purpose was written in C, here is the source file, C52ADC.C and the HEX code, C52ADC.HEX. After some initialization, the 711 chip wait for trigger read signal at pin RB0, i.e., high-to-low transition, then it responses by sending 40-bit through RA4(SDA) with low-to-high transition. 40-bit data stream begins with LSB of ADC0 to MSB of PORT B. Example of program fro testing ADC is ADC.C and the hex file is ADC.HEX.

Figure 3: Using PIC16C711 to be a 4-channel ADC and 7-bit input port for C-52 EVB.

Simple Power Supply and Charger Circuits
Figure 4 shows a simple power supply circuit. I have tested with KABO, it works fine. For those who have a big capacity rechargeable battery, the resistance value of R can be selected for approx. 10% output charging current. DC in can be higher if your battery voltage higher than 8.4V, say. To ensure the output current is within the value calculated by R, measure DC current before. The maximum supply for LM317 is ~35V.

Figure 4: Circuit Diagram of battery supply +12V Alkaline and +8.4V NiMH with a constant current recharger circuit. For ~20mA, use R~60 Ohms. S1 is main switch for CPU and L293 circuits.

Using PAUL’s Startup Header file with Micro-C

Before writing PWM generation for testing above circuit, let study how to use Paul’s header. With a PAUL’s startup header at the beginning of the application C program, after successfully downloading the hex code, just press RESET, the 89C52 then will run the application instead of PAULMON2 monitor program. As long as the program remain in SRAM, running the program can only be done with pressing RESET. To return to PAULMON2 prompt, turn the board power off for a while, then back the power on again. This concept of startup header allows us to use C-52 EVB as a dedicated controller beside as a learning board. Originally Paul has made with entirely in Assembly code. However, I have adapted for Micro-C Compiler. I have put the header for startup code in the startup and runtime library for small memory model. The file C52ROBOT.ASM, will compile and link to the main( ) function with S=c52robot.asm when invoking command coordinator. Example of command line is;c:\mc\cc51 %1 -ilp h=c:\mc m=s s=c52robot.asm%1 is hello(.c), sayLet try hello.c and compile with above command line, download the hello.hex into the C-52 board, then press RESET, see what happen?

Control Program demonstrates PWM generation with KABO

`One method of delivering DC power to motors is to use PWM. The PWM method supplys DC pulse with fixed frequency but with adjustable duty cycle. I used TIMER2 in AUTO reload producing 1000Hz PWM frequency. Each time executing has entering into service routine, a 16-bit PWM1 was shifted out to P1.7 and PWM2 to P1.6. Main program has a task that set the power for motor1 and motor2 by writing 16-bit PWM pattern into PWM1 and PWM2 for motor1 and mortor2 respectively. The service routine for timer2 is put in startup code.

See example program, KABO1.C and C52ROBOT.ASM, for PWM demonstration with manual control. I have designed and built my own robot for the competition also. It names KABO having differential drive method. As shown in right-hand side, is the rare part powered by C52-EVB. The motor driver chip L293D and a 74LS04 are put at the soldering pad.

Ving-Peaw Competition

I suppose there should have ten robots to be competed. Details Rule and Scoring will be launched soon, day by day changed. But first of all, competitors must know how difficult of the circuit and programming are. Hear is the actual course layout.

Figure 5: Actual Course Layout for Ving-Peaw Robot Competition

The original idea of what kind of the competition would be, came from Zongwit. Each round has two robots. Each robot must run along black tape and try to touch the the other’s target. Who touch first will be the winner. The slower is allowed to detect the faster, shifted out of the line for 20 seconds, then back again. No limit for the robot size and uControllers, you may use ranging from a PIC16F84, 16F873/877, 89C2051/4051, 89C51/52/55, or 68HC11, say.

source: mytutorialcafe.com