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ArchivesFailureBot 5 - A Line Following Robot
May 27th, 2006 |
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| FailureBot 5 - Complete Robot | FailureBot 5 Following A Line |
Introduction
The objectives of the FailureBot project originated simply as "build a line-following robot". However, it somehow evolved into a 3-year robotics experiment. My first attempt to build a robot was such a complete failure that I jokingly called it "FailureBot". The name seemed quite appropriate even as the project evolved as every one of the many, many failures yielded a critical lesson in the robot-building process.
For me, hobby robotics is about creativity. I didn't want to throw a couple sensors on a robot kit, I wanted to build it from the ground up. Looking through catalogs, reading datasheets, and building the robot within the constraints of my limited resources was the ultimate experience. Much of this robot is built from raw materials and hardware available at local hardware stores-- and done so on a very limited budget. Throughout the process, I kept a couple of concepts in mind:
- Close enough is good enough. I'm not a NASA engineer, I'm a hobbyist. It doesn't have to be perfect, it just has to work. This is especially true considering that my "workshop" is merely a bedroom floor and a Dremel rotary tool. I don't have the facilities to make straight cuts or aligned holes. Improvise.
- The overall goal is to learn and discover. When it felt like I was re-inventing the wheel I just reminded myself that I was learning how the wheel was invented.
- Success is a series of failures. It can be very discouraging to spend large amounts of time only to hit a dead-end and start over. This is FailureBot 5 because I've had to start over from scratch 5 times with the physical construction. The lessons learned made it very much worth while.
- Work within your means. I would often get discouraged by what I see other people building--making molds, welding, etc. I don't have those resources nor a large budget. A roboticist shouldn't be thinking about how it is supposed to be done, but how it could be done considering the elements.
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| FailureBot 3 - Alluminum Frame/PIC16F627A | FailureBot 4 - Breadboard/PIC16F877A |
Line Following Robots
A line-following robot, or "line follower" is a pretty common type of robot for hobbyists. Robotics competitions usually have a line-following event. The line is usually a black line about 3/4" wide, such as black electrical tape, on a white surface. Advanced courses may add new challenges such as inclines, tighter turns, intersections, thinner lines, or changing line colors. The robots typically sense the line by measuring light reflected off the ground, where a black line reflects little/no light and the white floor reflects a lot of light back.There are TONS of websites relating to line-following robots as it's a very common beginner project. The Robot Room has some great information on a couple of line following robots.
FailureBot 5 Overview
FailureBot 5 is actually a fairly good robot base which could easily be adapted to maze solving, obstacle avoiding, or other applications of a small, 2-wheeled robots. However, at this point in time, it only follows a line. The robot consists of 2 plastic round decks, differential drive using 2 DC gearhead motors, a sensor board with 5 photo-transistor/LED sensors, an L293D H-Bridge motor controller board, and an Atmel ATMega8 processor board.
A sensor board with 5 sensors shines light downward at the ground. If the line is underneath the sensor, then the little/no light will be reflected back to a paired phototransistor. If the line is not underneath the sensor, more of the light will be reflected back. A microcontroller measures the output of each of the phototransistors through it's analog-to-digital converter (ADC). Based on the position of the line underneath the robot, the microcontroller adjusts the speed/direction of the DC motors to steer the robot.
Building FailureBot 5
Building the robot was the hardest part for me. I am by no means a mechanical engineer and had a lot to learn. FailureBot 5 is a round, 2-deck, 2-wheeled differential-drive robot.
A differential-drive robot works like a tank. The two wheels provide both the drive and the steering. By stopping one motor and not the other, the robot pivots on the stopped motor to turn. By turning one motor forward and the other motor backward, the robot turns in place. The wheels are offset forward slightly and a caster is placed in the back of the robot for support.
The Base and Second Deck
The base and second deck are 0.118" thick x 6" diameter Acrylic Circles purchase from Tap Plastics for $1.95 ea. They were cut to allow the wheels to be mounted within the diameter of the acrylic circles. The cutting as well as drilling holes for mounting motors and electronics was all done with a Dremel rotary tool. A piece of paper with drill/cut marks was taped over the acrylic circle as a guide for cutting. A piece of aluminum foil was also taped to the under-side of the second deck and connected to ground to serve as a sheild between the motors and the processor board.
The decks are connected to each other using 4" 6-32 screws with 6-32 hex standoffs spacing the 2 decks apart. I have no idea where I got the hex standoffs, but I'm sure they're pretty common.
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| Cutting/Drilling the Base with Dremel | Base with Motors, Controller, Wheels and Caster |
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| Second Deck with Aluminum Foil Sheild |
Motors and Wheels
In earlier attempts I had problems with motors not having enough torque to properly move the heavy robot bases I was building. I decided to buy gearhead motors with a very high torque and use larger wheels to make up for the loss in RPMs. There are 2 Lynx Motion Planetary Gear Motors (12vdc 189:1 31rpm) ($11.40/ea) which drive the two wheels. Each wheel is made out of two 4" round discs bolted together with 2 washers spacing them out. The discs are from Home Depot ($1.49/ea) which are used to cover electrical boxes. A 4" O-ring (also from Home Depot) sits in the gap between the two discs to serve as tires. These relatively large wheels allow the slower motors to suffice for moving the robot quickly. They are also nice and thin giving the robot the ability to easily turn by pivoting on one wheel. The wheels were then attached to the motors using a pair of the 6mm Universal Wheel Hubs from Lynxmotion ($8.00).
The motors are then mounted to the base using a homemade motor mount. Although Lynxmotion also sells motor mounts, I had already felt I had spent enough money on the motors. Home Depot (or Lowes, etc) has a section with weather stripping including long pieces of aluminum in various shapes and thicknesses. I picked up a right angle strip (4" wide piece of aluminum folded at 90 degrees) and cut it up using--once again--the Dremel rotary tool.
The motors are mounted slightly forward from the center-line of the robot and a caster from Home Depot ($2.95) was mounted in the back/center of the robot.
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| Lynxmotion Motor with Home-made Mount | Lynxmotion Motor with Home-made Mount |
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| 0.1uF Capacitors on Motor Terminals | Home-made Wheel and Lynxmotion Hub |
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| Wheel without Tire | Disassembled Wheel |
Sensor Board
The sensor board was one of the only things that worked since the very first FailureBot. There are 5 line sensors. Each line sensor consists of a single red LED and a photo-transistor. The electronics of the sensor board will be discussed later. However, the construction here does make a difference. The phototransistors will be sensitive to the ambient light in the environment and thus I want to keep that down to a minumum. I want the light from the LEDs bouncing off the ground back to the phototransistor to be the primary light hitting the phototransistor.
I used a piece of acrylic plastic (Home Depot and Lowes sell acrylic rectangles for a few bucks) which I spray painted black in numerous thin coats to ensure that it was opaque. Then, holes are drilled for the LEDs and photo transistors such that the LEDs protrude out and the phototransistors are set in a bit (see my sketch below). I wasn't too concerned with one sensor being skewed or protruding more/less as I knew I could have each LED independently calibrated via software (discussed later).
Finally, two 3" 6-32 screws with locknuts and wingnuts are used to attach the sensor board to the robot. This way, I can adjust the distance of the sensors to the ground manually by moving the locknut up/down.
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| Sensor Board (front) | Sensor Board (bottom) |
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| Sensor Board (top) | Sketch of Single Sensor |
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| Sensor Board Attached and Running |
FailureBot 5 Electronics
Motor Controller
The motor controller is a simple H-Bridge using the L293D ($2.70 from Digikey). 5 lines from the microcontroller are used to control the 2 motors. ENABLE runs directly to the EN pins of the L293D to disable the motors. M1DIR is the direction control for the left motor and M2DIR is the direction control for the right motor. M1PULSE is the PWM signal to run the left motor at it's desired speed (at the time of writing, the software isn't using PWM but running the motors at full speed) and M2PULSE is the same for the right motor. This is a very common DC motor control concept and thus I'm not going to go into further detail. A Google search will return numerous pages on the topic.
When testing the motors, I found that they pulled 50mA with just the wheel spinning freely and 590mA stalled. The L293D can handle 600mA per channel. Just to be on the safe side, I put a heatsink on the L293D though It was never necessary in any of the earlier versions running on a breadboard.
The most important thing I learned with this part was this: BEWARE OF THE NOISE FROM MOTORS! The motors can add tremendous noise to the supply even when using a separate battery for the motors than from the rest of the electronics (common ground). The solution was the capacitors on the motors. Three 0.1uF capacitors were used on each motor. One was connected between the motor terminals, and also one from each terminal to the motor's casing. I also added the aluminum sheild to the under-side of the upper deck as mentioned above, and twisted the wire leads to the battery. Michael Simpson's "Reduce Motor Noise" discusses these techniques in more detail.
(Click to Enlarge)
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| Motor Controller (top) | Motor Controller (bottom) |
Sensor Board
For each sensor, I used a SSL-LX5093SRC/E RED LED with a clear lens in a T1 3/4 package ($0.54/ea from Digikey) paired with an OP505B phototransistor ($0.59 from Digikey). Since phototransistors are designed for the infared frequency spectrum, I was looking for an LED with a relatively high peak wavelength and a phototransistor with a relatively low peak wavelength, or at least a broad bandwidth, so that their active bandwidths overlap. I had read that you don't want to use infared LEDs for line detectors as infared light does have the same reflective properties as visible light. In rhetrospect, I was being a little overly concerned here. I believe just about any red LED and phototransistor would have sufficed considering the ability to calibrate the sensors via software.
I did not want to deal with difficult hardware for the sensors. I knew the tools I have at my disposal will not allow perfection in terms of mounting these LEDs and getting each of the 5 sensors to behave the same. Each of the phototransistors outputs are tied together resulting in a single output line fed back into the ADC of the microcontroller. However, only one LED is turned on at a time via software. Each sensor is individually calibrated so that ambient light and variations in how each sensor is mounted are accounted for.
(Click to Enlarge)
Microcontroller Board
This robot has used a PIC16F84, PIC16F627A, PIC16F877A, and now finally, and Atmel AVR ATMega8. Whenever I'm learning to use a microcontroller, I make a little board for a common part (in this case the "mega8"). This allows me to experiement with the part without having to breadboard up the power supply and clock source each and every time. FailureBot 5 uses such a board. I take the board off and use it in other projects. So, this board is relatively generic. It simply contains the ATmega8 microprocessor with an 8.000MHz crystal oscillator, a low-dropout MAX667 +5V voltage regulator, and .100" pin headers for each of the I/O pins (My board also has the AREF pin at the header but is wired back to VCC for a +5V reference voltage).
(Click to Enlarge)
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| ATMega8 Board (top) | ATMega8 (bottom) |
FailureBot 5 Software
The software for the robot is written in C for the Atmel AVR microcontrollers using avr-libc and the GNU gcc compiler (open-source). The software is still relatively primitive, however, it works quite well. The robot is able to handle 90 degree turns, inconsistant floor color (tiles) and intersections at a very decent speed. At this point in time, my gear motors have such a high reduction ratio that I do not need to use PWM to change the speed, however, the robot was originally designed to allow for PWM.
When turned on, the robot spins in circles on the line for a couple seconds while it calibrates the sensors. Once this calibration is complete, the robot begins it's line detection algorithm in a loop, however, the motors are disabled. By pushing a button, the motors are enabled and the robot follows the line. Pushing this button again disables the motors again. So, the robot is always performing the line following, however, it only moves when the motor enable button is activated.
Calibration
During the calibration, the robot turns in place in circles above the line in an attempt to "learn" the lighting conditions of the environment. 2 values are setup for each sensor. A low value indicating the lowest value read from that sensor and one for the highest value for that sensor. At the end of the calibration, the middle of these two values is the "trip point" for the sensor. Anything above this trip point is considered high and anything below is considered low. Each LED is calibrated many times over, one at a time, as follows:
Turn on LED. Measure ADC value from phototransistor. If the value is lower than the lowest value measured, save this as the lowest value. If the value is higher than the highest value measured, save this as the highest value. Turn off LED.
Then, a trip point is setup as low value + ((high value - low value) / 2).
Steering
There are 6 directions defined for the robot.
| GO_LEFT | The left motor is stopped and the right motor goes forward. Robot pivots to the left on the left wheel. |
| GO_HARD_LEFT | The left motor goes reverse and the right motor goes forward. Robot turns in place to the left. |
| GO_FORWARD | Both motors go forward and robot goes forward. |
| GO_HARD_RIGHT | The right motor goes reverse and the left motor goes forward. Robot turns in place to the right. |
| GO_RIGHT | The right motor is stopped and the left motor goes forward. Robot pivots to the right on the right wheel. |
| GO_BRAKE | Both motors are stopped. Currently not used. Disable is used instead. |
Line Detection Logic
The robot decides which direction to go based on the 5 sensors. Each sensor is read one at a time and the bit value is stored in a variable. The bits are left shifted into the variable starting with the left sensor. Therefore, the leftmost sensor is the most significant bit in the variable. Based on the final result of all 5 sensors being left-shifted into the variable, the robot decides how to steer.
| Bit Pattern | Hex Value | Decision |
| 00100 | 0x04 | The line is in the center. Go forward. |
| 01110 | 0x0E | The line is center but really thick? Go forward. |
| 11111 | 0x1F | Possible intersection. Go forward. |
| 00001 | 0x01 | Line on right-most sensor. Go hard right. |
| 00011 | 0x03 | Line on right-most sensor. Go hard right. |
| 00111 | 0x07 | Line on right-most sensor. Go hard right. |
| 00010 | 0x02 | Line on mid-right sensor. Go right. |
| 00110 | 0x06 | Line on mid-right sensor. Go right. |
| 01100 | 0x0C | Line on mid-left sensor. Go left. |
| 01000 | 0x08 | Line on mid-left sensor. Go left. |
| 10000 | 0x10 | Line on left-most sensor. Go hard left. |
| 11000 | 0x18 | Line on left-most sensor. Go hard left. |
| 11100 | 0x1C | Line on left-most sensor. Go hard left. |
| ? | N/A | All other conditions, continue in the last direction determined. Line could be between sensors or there could be a problem. |
Posted on
Saturday, May 27th, 2006 at 3:28 pm
Categories
AVR Microcontrollers My Robots Robotics/Electronics
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October 2nd, 2007 at 3:56 am
Hey....this is a great project....i dont know if you can be of help to me but i really hope so...how would i go about building this same line follower but using the PIC16F877 and furthermore i dont want to use IR sensors but instead using photo transistors.....could you please help me.
thanks
October 2nd, 2007 at 7:38 am
Well, I did in fact use photo transistors in this project. They were paired with red LEDs with a high wavelength.
As for using a PIC16F677, it's almost exactly the same (at one point I was using that very microprocessor in this project). You'll simply have different processor board. The PIC has the ADC ports you'll need to get the data from the photo transistors and it also has dual PWM outputs if you need to control your motors. However, the motors I used were so slow that I didn't even need to use PWM--which makes the coding slightly easier.
October 10th, 2007 at 12:53 am
hey
Thanks for the help. Will shout if i need to know anything more.
:) thanks again
October 15th, 2007 at 5:11 am
hi there
i have a few more questions for you.....was there any particular reason why you chose to use red LEDs. What are the components labelled JP1, JP2 etc on your diagrams?
thanks for your time
Karan :)
October 15th, 2007 at 7:56 am
The red LEDs were chosen because red is closer in the spectrum to infrared. Most phototransistors are sensitive to IR light. By looking at the data sheet of each part, you can see where they intersect. I tried to find LEDs that had the highest peak wavelength I could find and phototransistors with a lower wavelength (relative to other photo transistors) to be sure they would be sensitive to my LEDs.
I didn't use IR LEDs because a) I wanted to SEE them working and b) I've read that IR light can behave unpredictable in terms of ambient light and which materials reflect it. Remember, the robot "sees" the line based on how much light reflects back. Obviously visible light reflects predictably because that's how WE see the line too.
The JPx components are connectors. I broke each part into it's own board, so I used .100 pitch headers to connect each of the boards. Those show how each of the boards are connected.
October 21st, 2007 at 3:31 pm
Hello,
Just started with microcontrollers using pic16f627a. Perhaps you could give shed some light on line following and obstacle avoidance using this chip. Using picBasic as the language. At the moment, i can connect the sn754410 motor driver chip to the motors but a little sketchy on the I/O for the sensors and the coding.
October 22nd, 2007 at 9:06 am
It's been a few years since I've worked with PICs and when I did, I used Assmebly language or C. Checking the state of your sensors will be much easier than controlling the motors. You simply check the state of the pin. There are a lot of PIC tutorials out there to help you with this.
You may also want to join a robotics club mailing list. I subscribe to Portland Area Robotics Group and Seattle Robotics. Both groups are very friendly and helpful when trying to work through the details of building your robot.
October 29th, 2007 at 6:29 am
hi...i have a zillion more questions for you.....here it goes...
1.could you provide me with the circuit diagrams etc from when u were using the pic16f877 as the microcontroller?
2. I want to use smaller wheels that i can easily source from a toy car(maximum 10cm in diameter). Can i still use the motor type you used or will i have to use another one? if so what do u recommend?
3.in your first circuit diagram is IC3 your microcontroller or the h-bridge?
4. on all the three different diagrams JP1 is connected to various points as in for example pin1 of jp1 in the first diagram goes to 4A on IC3 but in the second diagram the same pin1 is connected to gnd and then in the third circuit diagram pin1 of jp1 is connected to some thing on ic1....help me....i dont understand how to read the diagrams.....do you perhaps have a more complete circuit diagram of the whole system instead of breaking it up into different boards?
sorry for all of this....really need help though! thanks a lot...u are a life saver!
October 29th, 2007 at 3:42 pm
1. I don't have any schematics around for FailureBot 4 which used the '877. However, a schematic of FailureBot 3 which uses a PIC16F627 can be seen at http://www.micahcarrick.com/files/failurebot_3.png
2. Smaller wheels are fine, however, remember that it takes more revolutions to go the same distance when the wheels are smaller. The motors I used in this robot are quite slow (31 rpm). This robot went pretty fast (faster than many I see at competitions) and it or something like the GM3 from Solarbotics shoult work. However, if I were to re-do this project another time around, I would go with a bit faster gearbox such as the similar 64 rpm motor from Lynxmotion and use PWM to control the speed of the wheels (PIC16F677 or ATMega8 will both allow for PWM control).
3. In that diagram, it's only showing the motor controller board. So IC3 is the L293D H-Bridge chip. The microcontroller connects to this board through JP1 in the schematic.
4. I may not have paid attention to the numbering on the diagrams. I'm afraid the microcontroller board doesn't label which pin I connected to which connector on the supporting boards. You'd have to look through the source and then back to the schematics. If I find some free time, I'll make this more clear.
October 29th, 2007 at 11:30 pm
hey...thanks for the prompt reply! did failurebot_3 actually work?
October 30th, 2007 at 12:16 am
hi again......does failurebot_3 use the same Leds,phototransistors, h-bridge, motors as failurebot_5?
further more looking at the schematic of failurebot_3,obviously IC3 is the h-bridge but what is IC2 and what is it used for? what is the value of VDD to be used? 5V?
Do u happen to have the same type of schematics as that of failurebot_3 for failurebot_5? if you do do you think you could put that up like you did the other schematic? oh yes....for some reason i cant open the source code and eagle schematics for which you put a link on this page. Could you maybe share that the way you did the schematic for failurebot_3?
i am so sorry about being such a bother and you have no idea how great a help u have been. thanks a million again :)
October 31st, 2007 at 11:23 pm
hi again……does failurebot_3 use the same Leds,phototransistors, h-bridge, motors as failurebot_5?
further more looking at the schematic of failurebot_3,obviously IC3 is the h-bridge but what is IC2 and what is it used for? what is the value of VDD to be used? 5V?
Do u happen to have the same type of schematics as that of failurebot_3 for failurebot_5? if you do do you think you could put that up like you did the other schematic? oh yes….for some reason i cant open the source code and eagle schematics for which you put a link on this page. Could you maybe share that the way you did the schematic for failurebot_3?
i am so sorry about being such a bother and you have no idea how great a help u have been. thanks a million again :)
October 31st, 2007 at 11:27 pm
what is the purpose of IC2 in failurebot_3? did you use the same leds,phototransisors,h-brige,motors as in failurebot_5? did failurebot 3 work? do you have the source code for failurebot_3? thanks
November 1st, 2007 at 8:29 am
IC2 is a 3 to 10 line decoder. It takes a binary value on the 3 inputs to turn on (or off) one of the 10 output lines. Do a google search for "74138" for more information.
I don't have any other information on failubot 3 I'm afraid. It was never finished. I think it may have rolled around but that's it. Not entirely sure. Exact same phototransistors, motors, and h-bridge.
November 1st, 2007 at 11:00 am
okay...do you have schematic diagrams for failurebot 5(like the one you put up for failure_bot 3?) I am really desperate for it! Please help! and i cant open the eagle cad and source code files you have up on this website. could you perhaps post them the way you did the diagram for failuerbot_3.
thanks a lot.
November 1st, 2007 at 1:11 pm
I wouldn't have time to do that right now. I'm sorry.
November 1st, 2007 at 11:10 pm
thats okay...thanks anyway! what program do you need to open the source code and eagle schematics link you have on this website?
November 2nd, 2007 at 2:26 am
oh okay....thanks anyway
November 2nd, 2007 at 7:53 am
Oh right. They are opened using Cadsoft Eagle, available for FREE for Linux and Windows at http://www.cadsoftusa.com/
The .sch files are the schematics.
November 2nd, 2007 at 7:55 am
And by the way, the pins of the microprocessor are given names in the source code like M1PULSE which correspond to the M1PULSE pin on the schematic of the H-bridge. So if you look at the C source code you can figure out how the whole thing connects together.
November 4th, 2007 at 11:19 am
hey there....for some reason i can only download about 30% of the file on this website(i am talking about the link you have for your schematics and code). i thought it was me but i got some friends to try and download of their computers and they also had the same problem. do you think maybe the link is corrupt or something? help?
November 15th, 2007 at 12:10 am
hey there...need some help again....with your sensor board can you please help me understand the connections? from the jumper points LED1,2,3,4,5 and sensor out where do these wires go to? as in where do those points connect to from there onto the microprocessor?
November 15th, 2007 at 3:29 am
and did you use photo-comparators.....do you think you could repost your c-source code? please! Could you please just explain how the sensor board is actually connected? where does are the cathodes of the LEDS connected? do they go to some place on the microcontroller? and what about the collectors of the phototransistors? where does their common connection go to on the microcontroller? or do you use some sort of decoder? please help....it really is an emergency...i would be so greatful! thanks a lot
November 15th, 2007 at 6:55 am
I'm on my way out for a couple days. When I get back, I'll try to help you out.
November 15th, 2007 at 11:19 pm
that would be fantastic.Thanks
November 22nd, 2007 at 8:45 am
hi..can u send me the source coding for PIC16F877? i've tried writing on my own many times but failed.
i am doin the programming for Microprocessor based digital speed controller for DC motor.can u plz help me?
December 12th, 2007 at 3:47 am
hi...i don't know if you'd mentioned this in that description, but i wanna know do you implement the PID algorithms? in every serious project which connected to Line-Follower Building described that people used this tricks to callibrate data from sensors. have you heard about that? please, whrite me few words if you cleary know...
February 12th, 2008 at 6:08 am
hi....
pls help me 2 use PIC 16F877 for building the line following rbot....
wer 2 find d details abt the circuit diagram and source code for the microcontroller!!!
pls help!!
February 27th, 2008 at 2:42 pm
Hey there, I was looking at the video you have posted of your robot, and your design caught my attention! I am currently working on a robot for my senior design project and I am very interested in asking you a couple of questions.
1. What motor did you use on your robot?
2. Why did choose that one over any others you considered?
3. What were the other options you considered? (AC, Stepper, Servos, etc.)
4. Did you have any problems with the motor you chose? If so how did you fix it?
5. What are the fastest speeds and torque values?
6. Did you do any tests for choosing your motor? If so, what were they?
7. Essentially, what were some of the pros and cons of the motor you chose?
February 27th, 2008 at 2:50 pm
Akim:
Most of that is answered in the above article under the "Motors and Wheels" section.
I considered and tried the Tamiya Dual Motor Gearbox which didn't work because a) too weak, b) too slow, and c) I broke the plastic gears when the robot hit a wall and didn't stop trying to drive the motors. The onese I selected were primarily because they were overkill in terms of torque. With my large 4" wheels, I still got enough speed and since I didn't know my robots weight or home much torque I needed, I went over.
I did consider steppers only because I had some around, however, the "stepping up" and "stepping down" to start and stop is a little tricky and it required more I/O pins from the processor.
I didn't measure speed or torque, however, the wheels are 4" and the motors go 31 RPM max, so there's the speed. Stall torque on those motors is 295.34 oz-in.
As far as testing, I pretty much just attached my homemade wheel and put the motor in a vice and ran at full speed, using my finger to push on it and see how much pressure I could put without it stalling. I couldn't even stop it.
The only cons of the motors I chose is they might be pricier than the cheaper plastic ones, and that my speed was limited. However, the speed was much greater than that of most line-followers I've seen.
March 16th, 2008 at 6:41 am
hi..
me and my friend sibi planed to construct a line follower robot..
we selected your FailureBot 5..
we got all componets..
we have few douts..
1. In Motor Controller (bottom) which capasitor is used ...
2.we didnt get OP505B phototransistor . insted we got 3 pin transistor..
hope u will help us..
March 17th, 2008 at 7:34 am
how can the sensor diagram be modified with 3 terminal phototransistors??
March 21st, 2008 at 3:22 am
hi
can u explane conection between jp1 jp3 jp4 jp6 and motor control
March 22nd, 2008 at 9:26 pm
hi..
i am jahan.. i am from india...
can u explane the connection of port c in ur atmega8... in circute its seems like nu connected
March 23rd, 2008 at 10:56 pm
hi..
can u explane connection of port c.. were i have to connect the port c..
March 25th, 2008 at 7:28 am
You can see what gets connected to where by looking at the source code in main.c All the #defines at the top define which port bit becomes which "label" in the schematic (M1PULSE, etc.)
So, PORTD is for the LEDs PORTB is used for the motor control, and PORTC contains the ADC pin we need to connect to the photo transistor.
May 6th, 2008 at 2:26 pm
Hi Micah
can I use a LM7805C instead of the MAX667CPA?
Thanks and regards
Rodrigo
May 6th, 2008 at 2:51 pm
Yes, an 7805 regulator or any other 5V regulator is fine. I used the MAX because a) I had it lying around and b) it's more efficient.
May 10th, 2008 at 7:42 pm
Why do I get compiling errors?
May 11th, 2008 at 4:57 pm
Is there any other motor that i can substitute instead of the one here, becuase the one you have is out of stock...
May 13th, 2008 at 5:05 pm
Hi...The motor that you have on the tutorail is out of stock and I was going to buy a 65RPM motor...can you please help me use PWM speed control?
I would really appreciate it. Thanks
May 16th, 2008 at 7:31 pm
Fix the compiling errors(i make a stupid mistake)
May 26th, 2008 at 10:26 am
hi.......where can i find the source code for line follower robot using picaxe 14A
May 30th, 2008 at 4:04 am
can u pls tel which phototranistor u used .
can i use 2n5777 phototransistor .
u r work is excellent, especially u r code.
June 1st, 2008 at 9:53 pm
y do u use 8Mhz crystal, can we use 1 Mhz crystal present in atmega8 itself
June 3rd, 2008 at 6:28 am
pls reply to this
u said u connected the phototransistor(sensor out) to portc, but there is no initialization for that in the code.
June 8th, 2008 at 12:51 pm
help me
June 9th, 2008 at 9:35 pm
hi.
your web is very good , your robots too.
i have some questions for you .
how many motors rpm in FailureBot 5 ?
i want build a line following robot but i want use 5 optical sensors with your arrangement sensors. do suitable these sensors for line following ?
thanks.
June 16th, 2008 at 7:26 am
Hi Micah
what you mean by 'pushing a button' so the robot start to follow the line? I can't see any buttons ;]
Thanks