HD-Bot

Let's Make Robots Robots
1

HD-Bot is my first intend in building robots. His name is is derived from his chassis, which is an an old hard disk case. There is no controller onboard, the motors are controlled by a comparator chip (LM393). The line sensors are build with 2 CNY70 infrared opto reflex couplers. In a future version, 2 LDRs for light detection and a collisision detector are planned. For this reason a 4x2 analogue multiplexer is also needed.

 

Sensors

  • 2 x CNY70 as line follow sensor
  • 2 x LDRs for light detection (planned)
  • 2 x IS471F OPIC for collision detection (planned)

Actors

  • 2 hacked Servos (continous mode, without motor drivers)
  • 2 logic level FETs (IRLZ34N) as motor drivers



Control

  • LM393 comparator chip
  • 74LS14 Schmitt Trigger
  • DIP Switches forMode select (switch left/right)
  • Potentiometers for trigger value

 

the block diagram shows the full featured version.

The chassis build from a hard disk case, hacked servo with attached model plane wheels.

chassis

 

The line sensor with the CNY70 IR reflex couplers.

line sensor

 

The motor driver board. Just 2 logic level FETs.

motor driver

 

the "brain". IC socket for LM393 comparator and 74LS14 schmitt trigger and a lot of dip switches for mode select.

 

control

 

The following truth table helps to explain, how the logic control works:

truth table line sensor 

As you can see, the motor outputs needs to be inverted against the sensor inputs. The disadvantage of this simple solution is, as you can see in the video: if the robots misses the line it simple stops. 

to be continued...

Follows a line without a brain

  • Actuators / output devices: hacked servo motors
  • Control method: autonomous
  • Power source: AAs (1.2V each)
  • Sensors / input devices: CNY70, line follower
  • Target environment: indoor
This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/hd-bot
2

Analog / Digital bots

This is pretty interesting, getting a robot to follow without “programming”. Looks like a very simple, well thought out circuit. I’ve seen another like it called “2-Tran” I think, that had a couple sensors, and 2 drive transistors.

I like your chassis too, looks pretty sturdy. Pretty good idea to use the HD case, it’s fun to see different things remade into robots.

3

I could not make this if I

I could not make this if I had a million years! :slight_smile:

All electronics, no brains… It is like making a fish sing or a candle to burn without light or something :smiley:

4

Hi folks,thanks for your

Hi folks,

thanks for your replies. I added a truth table to the article to demystify the logic control. It is the same principle then for other robots without a microcontroller brain. 2 sensors outputs are converted to digital logic values (for example 0 meens black, 1 means white) and control the motor drivers directly. I just added some more logic to swap the sensors (left sensor to right motor a vice versa) and to independently invert the sensor output (with dip switches and inverter gates).

Thats all :slight_smile:

5

Interesting quote

There is a electronics guru, Steve Ciarcia of Circuit Cellar, who says, "My favoriate programming language is solder."

Or something like that, anyway.

6

Hello! I’m a student from

Hello! I’m a student from China.I’d like to know how your Robot keep Balancing?Do you know the thiory of kalman filter? if you know that, I hope you can tell me . thank you(my english isn’t very good)

7

It has a third wheel (not

It has a third wheel (not shown in the foto), so it needs no balance keeping. LMR user Nicola has succesfully build a self-balancing robot. Information about Kalman filters can be found in his blog. So you better ask him.