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Re: what type of sensors are good and convenient
Wheel encoders, limit switches, sonar rangefinding sensors, current transducers, IR rangefinders, gyros/accererometers, focused Optical sensors, potentiometers, HAL effect sensors, pressure transducers.
Wheel encoders - Measure rotation. come in two varieties: incremental, which can be used to measure speed, and absolute, which give the angular position of their input shaft. Note: the pulses from incremental encoders can be counted up to derive angular position(integration). Limit Switches - Switches that trigger when something hits them. Limit switches ae commonly used to determine when a mechanism is at its minimum or maximum position. These are very cheap and very easy to implement. Potentiometers - Measure angular position, but are limited in how far they will turn. Again cheap and easy to implement. Usually at least one of these comes in the kit. The can be had for like $1 anyway though. Current Transducers - Used to determine how much current a motor or other electrical component is drawing. These come in many varieties including shunt resistors and HAL effect based models. Some HAL effect current transducers can be directly connected to and read by the robot controller with very little effort. [b]Gyros and Accelerometers[b] - Gyros measure angular rate of change. This can be integrated to get something like a compass reading. They can also be turned in other directions to measure azimuth etc. Accererometers are similar to gyros except that they measure linear acceleration. The output from these can be integrated to get distance. Implementation of gyros can range from relatively easy to very difficult. Usually a gyro comes in the kit Focussed Optical SensorsThese measure reflectivity or coloration of an object. When used in pairs or groups they can be used to follow the lines drawn on the feild. Many teams did this last year to find their way up the ramp in autonomous. They can also be used in many of the places where you would find limit swititches. Last year we got a bunch of these in the kit. They are digital and trigger at an adjustable light/color threshhold. IR and Sonar rangefinders - measure distance from a distance. These come in many forms. Some can be easily used with the analog input on the robot controller, and other require use of a serial port. Relative cheap $10-$80 and pretty accurate. Jsut a few off the top of my head. |
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