Infrared Ground/object Sensor for Robot Navigation




i used this sensor on 2 of my robots. those were working on a table surface, so the robots had to detect when they have arrived to the edge, to stop, and turn back... it can sence also obstacles in the way.


Step 1: A Simple Version With Bipolar Transistors

first i made a simple version with bipolas transistors. the full schematics of that small robot is attached (not the same robot as in the front page).

the point in the operation is:
1. an oscillator generates a square wave.
2. an infrared led with narrow angle transmits this signal as infrared light/ray.
3. this is reflecting back from obstackles within the viewing angle, basically from a viewing spot on the ground, or in front of the robot.
4. there is a photodiode or phototransistor next to the IR-LED, with also narrow angle pointed to the same spot as the LED was. phototransistor was used on the bipolar version, and photodiode on the IC version.
5. there is a receiver circuit connected to the sensor, detecting if there is reflected signal or not.
6. if there is a signal (within a specified frequency band, like 5khz-150khz), then the output goes to logic high level, otherwise to low level. this signal can be used by a microcontroller, or by an analog control logic. there is signal if there is an obstacle/ground within the sensing range, which is about 5-15 centimeters.

Step 2: More Difficoult Sensor

i used this sensor on my last robot. this uses a remote controller receiver IC, the TBA2800. more reliable than the previous one.
as a sensor, i have used the BPW24R from Vishay semiconductors, and the SFH481 IR-LED from OSRAM.

Step 3: Sorry, Thats It.

the end.

Second Prize in the
Instructables and RoboGames Robot Contest



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    6 Discussions


    8 years ago on Introduction

    I did something like this. Use the microcontroller to strobe various LEDs on the robot and measure the output directly from them with it's 4 analogue inputs. It measured the voltage from a phototransistor when the LED was both off and on.. and could approximate distance (if used in a maze where the walls all had the same reflective properties). Found it worked at a lot larger ranges with normal white or red LEDs than with inferred and a phototransistor or LDR.. but maybe that was just the Inferred components I had


    10 years ago on Step 2

    hi can u make me one of that sensor you build i willing to pay u and send me some videos so i can see if it is really working reply as soon as possible

    1 reply

    Reply 10 years ago on Step 2

    sorry, but i am not making anything anymore, i am a hardware development engineer (only designing computer motherboards). i dont want to waste my time on this for you, the 50-100 dollars what you would pay wouldnt compensate me. i am afraid, you have to buid it yourself. or ask an electronics technician to make it.


    10 years ago on Introduction

    Whoa, this is some schematic. It reminds me of the "good" old times, when i started out with electronics.(Well we had OP-Amps like the 741 back then...) We used to produce infrared light barriers on "thick film", these are ceramic substrates with screen-printed conductors(silver-palladium) and resistors(carbon compound), the rest were SMD devices. This was 25 years ago, SMD was rather high-tech then. It's nice to see someone, who can still use plain transistors not only to increase the current of a controller output...

    1 reply

    Reply 10 years ago on Introduction

    hi. actually, a have designed this transistor circuit in 2000, so a littlebit more than 8 years ago.