Morse-Code   |     home
Basic Robotic Sensors   |   Op-Amp Circuits   |   Basic Semiconductor Circuits   |   Motor Control Circuits   |   555 Timer Circuits   |   Digital Logic Circuits   |   LED Projects and Other Optoelectronics Circuits   |   Microcontroller Based Circuits   |   Communication Circuits   |   Misc Circuits   |   Resources and Links
Basic Robotic Sensors
Basic Sensory Devices for Hobby robotics....
Any robot would not be very usefull if it could not interact with its environment in any way, imagine being blind, deaf, mute and try to maneuver in an "unknown" environment.
Our senses are an integral part of our lives, if not life itself! It would be good to build atleast one of these senses into a robot design, the more "senses" a robot has, the more it can interact with its environment. Which allows for more sophisticated tasks as it goes about its business on its own.

These are really basic input senses for a robot, that cover the very basics of "Touch Sense", "Sound Sense (Hearing)", and "Sight Sense". There are more complicated ones out there for speech recognition and "robotic vision systems" for more complicated tasks, unless you are trying to listen to a specific kind of sound, see a specific image pattern, or feel  for a certain "feeling", circuits for sound / sight / touch detection are simple and straightforward. These are the real basic Inputs I use in my robots...

There are all types of switches available in the market, used for all types of applications as a means of various inputs... I like to use levered cherry switches for robot bumbers and object collision detection (better late than never, obstacle avoidance sensors are more usefull in most cases where you don't want your robot scarring up the walls or furniture, or maybe even bruising your shin!) These types of sensors should be used as a last resort type of sensor used in conjuction with IR rangers or ultrasonic rangers for detecting obstacles... I usually curl the end of the lever to give it a smoother surface for it to "glide" against objects rather than scratching it.
"Cherry" (Cherry is a Brand name for these type of snap action switches)

switches are usefull as bumper switches and or limit switches. The built in Lever actuator makes it easier to implement in some robotics applications.


Various styles of Tactile Switches are also available...


There can also be some simple analog output pressure sensors that can be implemented using the conductive foam that IC's are usually shipped on...
 the use and connections are pretty much the same for the Photocells for analog output, since they both work with varying resistance. I usually make them by sandwiching a piece of conductive foam between 2 pieces of copper clad circuit board material, I solder some wires to the copper side of the boards and place them copper side to the foam, I then finish it off with  heat shrink tubing...





Typical Normally Open Connection.

Typical Normally Closed connection








Typical conductive foam interface circuit (R1 = 10K to 1M, or use a variable resistor with a 1K inline for variable sensitivity.).
Photocells can be used as a type of "robotic eye" that can be used to detect different light levels. Most usefull if used with an ADC. A lot of times I would put a variable resistor in line with a fixed 1k to 10K resistor to add adjustability to sensitivity, that way I can adjust the sensors to be more sensitive or less depending on what application I am using them for.
Typical Photocell interface circuit
Photodiodes / Phototransistors are also usefull for detecting light especially in the IR region of the spectrum or even Lasers..... I use them in various circuits in conjuction with IR LED's for making line following sensors, obstacle avoidance sensors, proximity, etc.... These are usefull when making a robot that would rather avoid a collision rather than detecting it after it happens.

Typical Phototransistor circuits, circuit on the right is good for proximity detection, or for line following.

Microphones can be used for detecting sounds, can be easily implemented if not trying to detect a certain sound but just loud sounds in general... these can be easily intergrated with an Op-Amp to detect certain sound levels....
You would need a much more sophisticated circuit to listen to certain tones or sounds, but this works as a go /no go sound detector.







Simple MIC Preamp for connecting to amplifier...

More to come soon......



Back to Electronics Main Page