Robot - Wall Avoiding (Plinko Robot)

I am looking to build a robot that will travel and zig-zag down the hallway.It will be headed towards a wall at roughly 45 degrees and then use a IR LED to detect when a wall is nearby. From there, the robot will rotate and head towards the other wall at a 45 degree angle. The robot will zig zag back and forth until it reaches the end of the hallway.

I have researched a lot of various robots using a search of "Obstacle Avoiding Robot". However, all of these designs use IC L293D motor drivers. However, for my class, I am only able to use a select few diodes, power MOSFETs, BJTs, OP-amps, and 555-timers, and no microcontroller.

Can anyone give me advice on how to create a motor driver using these parts? Also, do you have any additional tips to help me build this robot?

Thank you!

• It will be headed towards a wall at roughly 45 degrees ... that is a faulty assumption ... it could easily not travel in a straight line – jsotola Apr 10 '20 at 18:58

Perhaps what you are looking for is a Braitenberg vehicle. These are simple theoretical vehicles that exhibit advanced behavior without traditional microcontrollers. (The Wikipedia page is just a small summary of the full book which is definitely worth a read).

These vehicles are typically concerned with driving towards a light source. But I think you can probably use two distance sensors instead of light sensors to drive down the center of the hallway. Maybe like this:

Assuming the distance sensors return a small value when close to a wall, and large value when far from a wall. For example the left sensor is close to the wall, and the right sensor is far, so the right motor gets a small signal and the left motor gets a large signal, thereby steering the robot away from the wall.

• Do you have a specific schematic that I could go off of to begin work on? I am not having much luck! Thank you for your response. – CPK Apr 11 '20 at 15:22

This looks like a BEAM robot. According to Wikipedia, "BEAM robotics (from biology, electronics, aesthetics and mechanics) is a style of robotics that primarily uses simple analogue circuits, such as comparators, instead of a microprocessor in order to produce an unusually simple design. While not as flexible as microprocessor based robotics, BEAM robotics can be robust and efficient in performing the task for which it was designed."

The BEAM Reference Library provides an overview of the paradigm, an extensive library of commonly used circuits, and schematics for some robot designs. In particular, I believe this one might be a good start for you: it desribes a robot that drives in the direction of a light source, I imagine that with a few modifications it could be reworked into moving away from obstacles instead.

• Do you have an example which I could look at? I am trying to build it in Multisim and need some help getting started. Thank you! – CPK Apr 11 '20 at 15:23
• Search for "beambot photovore" or "beambot 555 timer", there are many sample projects around, often with schematics. This one is as simple as it gets: robotshop.com/community/robots/show/555-timer-photovore-robot – xperroni Apr 13 '20 at 17:24
• Most projects use light sensors to have the robot drive from / towards light sources, you'll just have to adapt one of them to use IR LED's. – xperroni Apr 13 '20 at 17:26