My Robot 2

Hi, this is my first post in LMR, and I like to present my second robot. By the way I am a 17 year old student located in Sweden, in northern Europe.

The second video is the best one.

I have designed and build all the parts of the robot, including the ultrasonic rangefinder. The only exception is the H-bridges for the motor drives, and of course the pressure sensors. The H-bridges are mounted on a surplus item containing IPS-031 power switches and optocouplers. The H-bridges are controlled by two PIC16F690.

The ultrasonic range finder is also constructed around a PIC16F690. It is probably not as efficient as the ones that are available in the market. But I have learned a lot by building it myself.

The design of the bumper sensors are also a bit odd. I use a silicon hoses which are connected to a couple of pressure sensors. The analog pressure outputs are converted to digital by two PIC12F863. These MCUs also controls the LEDs in the bumpers.

The main “brain” of the robot is a PIC16F887 running at 20MHz. This PIC also listens to an IR-receiver, which can receive “high-level commands” form a also home built remote controller. This controller can also be used for completely different purposes, like controlling the lights in my room.



Updated 16/10   2010

 New features: I have built four infrared sensors, added a speaker controlled by a SpeakJet voice synthesizer chip and improved the firmware. Now the robot has a little bit more complex behavior and support for the new features. I have also made a new video. 

The four infrared sensors are mounted on the front bumper. One facing forward, one upward, one left and one right. The upward facing sensor is just to prevent the robot from driving under my bed and other similar things. All four sensors are all controlled by a single PIC16F690 microcontroller. The MCU reads the analog signals from the IR phototransistors with and without the IR LEDs on. If the difference is greater than a specified number there is an obstacle in that direction. The PIC16F690 then sends this data to the main microcontroller as four digital signals.

The SpeakJet voice synthesizer chip is controlled directly by the main MCU. The Speaker is connected to the SpeakJet through an audio amplifier. That makes the robot able to speak really load if I want it to. The SpeakJet also makes some beeps and sound-effect when the robot sees obstacles.

Hope You like my robot, Regards Axel

Navigate around while avoiding obstacles with ultrasound, infrared light and air pressure based bumper sensors.

  • Actuators / output devices: one servo, 2 geared motors, speaker
  • Control method: autonomous, infra red semi-controlled
  • CPU: 2x PIC12F683, PIC16F887, 4x PIC16F690
  • Power source: nimh, 7.2V, 2000 mAh
  • Programming language: Assembler, C#
  • Sensors / input devices: IR, bumper sensors, Home built ultra sound
  • Target environment: indoor

This is a companion discussion topic for the original entry at

Beautiful! Wonderful

Beautiful! Wonderful pictures, video, and of course a wonderful bot. This is Quality.

Nice light effects!

Thanks for posting. That is indeed a beautifull piece of work. The bump sensors are very innovative (for this community anyways). Would you post a walk through about them please.

That’s some really nice

That’s some really nice work, looks nice, works nicely, 5 stars!

Very very impressive!!

Very very impressive!!

Now this is just one of the

Now this is just one of the best way to show off your stuff :slight_smile: nice nice nice :smiley: and thumbs up for your first post man :smiley:


Most impressive! How much time did you spent doing it?

Very clean and functional

Very clean and functional design, great job!

Beautiful! Just Beautiful!

Beautiful! Just Beautiful!

And your bumpers are great. Like rik already said, a walkthrough would be greatly appreciated.


A real eyecatcher. Great

A real eyecatcher. Great work. Using pressure sensor as bumper detectors is very creative. What happens to robot 1?

Thank You all

Thank You all for nice comments. I will try to make a walkthrough regarding the air pressure based bumper sensors.   


This is my Robot 1

This is my Robot 1, This project was finished in 2009


Nice robot, Axbri!Funny

Nice robot, Axbri!

Funny secondary aspect: I also had the idea with the silicon hose as a bumber sensor a few month ago. Instead a pressure sensor I wanted to use a piezo buzzer like picture below, affixed with a connection nipple. I also thought on a condeser microphone, like a electronic stethoscope, but never built it actually :slight_smile:


robot 1

Robot 1 is great! Why don’t you post it here as a separate robot?

Also, why do you need bumper sensors when you have ultrasonic object avoidance? Anyway, the idea you had with the pressure sensors is very creative!

A walk through of your home

A walk through of your home designed ultrasonic rangefinder would be great!

Nice work on both robots, and on the individual components you made to create them.


I must admit the documentation of my rangefinder is in to bad shape to be presented as it is. However I will try to explain the rangefinder briefly.

First the PIC16F690 sends a burst of 8 pulses a 40 kHz. The signal is amplified in one transistor before it is sent to the audio transmitter. There is also a coil in parallel with the transmitter unit. After this the MCU waits a short while to exclude mechanical feedback before it starts to count time, wait and listen for echo to come back. The signal from the audio receiver gets amplified and in three LM224 OP-amps before it is sent back to the MCU. The rangefinder MCU converts the time for the echo to come back into a 4-bit word that is sent to the main MCU. As you can see in the video those signals are also visible on the 4 green LEDs.



Your robots are incredibly well built. I think they are the cleanest robots on LMR.

I feel inspired to build something!

Thank you

Thank you, I am glad I have inspired someone! I will post some new updates regarding my “Robot 2” very soon.

Wonderful! Both of them

Wonderful!  Both of them are real show-stoppers. Well done

Well done!!!the design is

Well done!!!

the design is super and very accurate