Let's Make Robots!

Analog 1 wall following

Follows a wall until a light turns off/on

**Update 9/27/2012**

     Finally got around to adding a whisker to the robot that I'm happy with, it helps the robot get stuck far less then before, also it adds a third behavior with only 2 more components \o/.  I added a different battery pack as well now it has 6 1.2volt 2500mAh NIMH cells.  I changed from li-ion to NIMH for the more forgiving attributes, as now I'm attempting to build a solar panel for the robot.


      I picked up 9 or so cells from a surplus store for dirt cheap and wired 5 in series with a Schottky 1N5819 diode for reverse protection.  Full sun specs tested in field for the array was 7.33volts at 283mA. While I was at it I moved the componets over to a proto board and encased the cds sensor in a metal casing that will be mounted on the panel later. below are some of the updated pictures.


     The circuit works the same as before just now the microswitch will switch the resistance of the 556 in turn reversing the right servo. Though it is far smoother at following a wall after some very fine tuning. I will need to work on the adjustment of the pot for the light sensor so it will stop only at a bright enough light source that will charge the batterys.  Now a charging station will be as simple as wiring up a powerful lamp to a timer.  So soon it will be a completely analog wall following solar powered robot.


 *Updated/Larger schematic*

       This is a robot I decided to make over the weekend, or at least the analog brain for it. I've had the base done for a while now.  I received some breadboards and a jumper wire kit and decided to replicate a 556 timer controlled, wall following robot I saw on Make.

       I've stumbled upon a few problems in the original schematic so I drew up my own. I also had enough room left on the medium breadboard for a light/dark activated switch, this added another behavior to the robot.  It uses a 741 op amp, one 556 timer, and various components to control the signal to the servos connected to the wheels.  The 741 is just to buffer the incoming signal off the long range IR sensor. I hope you guys enjoy this robot since it's very fun and easy to make.  The hardest thing about it was adjustment of the potentiometers but you only have to do it once :). 

      The base is made out of hand-laid carbon fiber, the battery is a li-ion 4800mAh battery. It's a very light wieght and strong base. You don't have to go as fancy as the DC-DC converter you can easly replace it with a simple dropout regulator as well, though you may have to use a heatsink.  One of the potential abilities of this robot is, if it has a solar panel, and a certain amount of light hits the cds sensor it will stop and charge from the incoming light.  Also, when the sun sets and/or the light turns off or dims, it can continue following the wall.  Thus creating a very simple self-charging analog robot. Enjoy!!  If you have any questions, just send them my way.


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Only I have one question...

Are the servos of continuous rotation ?

I have 2, but only rotate 180° degress... 

If so, how I can convert the servos to be rotation continuous?

I hope answer.

Thank you for helping me

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Amazing what behaviors can be realized with a handful of parts.......The analog functions, awesome, right up my alley ;))

I assume you're going to add more parts/behaviors to the original design and keep it growing?

Good job!


       yep still more to come. I plan on adding the solar panel as well as a different battery chemistry that's a bit more forgiving as far as being charged by a solar panel with minimal circuity. I plan on adding a diode (though it may be to much of a voltage drop) after the 741 op amp and then feeding a bump sensor into that area as well, this will allow it to be less prone to getting stuck, Ive also been looking at a way to add a sound sensor into the mix. I will try and keep updating the schematic as I go as I know it will help others.  End goal is a self charging mostly aware analog robot with minimal part count.



I like ... runs smoothly .. looks good ... and seems quite simple to make ...

It um..well uh..it..looks uh..kewl...great uh..bot. Looking forward to uh...seeing um...more of your uh...bots. : )

I don’t know if your comment is ironic but the robot and documentation from DoCDoC is great and anyone that can build a wall following robot without a microprocessor deserves respect!
I personally think that an analogue robot is way more impressive then a PICAXE or Arduino based SHR.

I agree. Making a robot with discrete parts takes skill.

Nice work!

Thanks for your support Its not a easy thing to get what you are looking for out of a analog structure but it does make for a interesting build.



...i'm sorry if i disrespected anyone, it's just that i wanted to coment something funny once in a while, thats all. I too, am impressed with it. It's just that i did that it in a pun way.