This is an old revision of the document!

---

====== Human Detection Sensor System ====== The human detection sensor system consists of a variety of sensors oriented in such a way that they can be used to detect and track the presence of humans. In our current design, there are three types of sensors: PIR Motion Detectors, Infrared Thermometer Arrays, and an ultrasonic distance measuring device. ===== PIR Motion Detectors ===== {{ :gallery:pirsensor.gif|Courtesy of Glolab}} These sensors are comprised of a [[http://www.glolab.com/pirparts/pirparts.html|Pyroelectric Infrared Sensor]] along with a custom designed amplifier circuit. A datasheet for the Pyroelectric Sensor can be found below. Due to the complexity of the amplifier circuit, the team decided to print PCB's for these boards - an attempt to save time and effort. {{:pir-diagram.jpg?150 |Courtesy of Glolab}}The Pyro-Sensors is used to detect the movement of humans (or any heated body) in a defined field of view. These sensors work by using two active elements to detect relative direction of motion of a heated body. When an object moves in the sensors field of view, a voltage waveform is produced. An example waveform can be seen to the left. Each sensor has about 90 degrees viewing angle but, with the help of a Fresnel lens and blinders, the final setup will consist of four sensors each with 45 degree viewing angle. The output from the Pyro-Sensors cannot be read directly into the microcontroller, so the team has constructed an amplification circuit capable of amplifying the signal with a variable-gain of over 10,000 (80dB). The amplifier is a simple two-stage Op-Amp circuit using the LM324 series Op-Amps. The amplifier circuit can be seen in the gallery below. ==== Datasheets ==== * {{:datasheets:pirmanual.pdf|Pyroelectric Infrared Sensor}} * {{:datasheets:lp324n.pdf|LP324N Op-Amp}} ===== Infrared Thermopile Array ===== {{ :gallery:thermopile.jpg?150|}} The TPA81 has an array of eight thermopiles arranged in a row. They can measure and report the absolute temperature of 8 adjacent points simultaneously as well as the ambient room temperature. The eight points are measured at increments of 5 rotational degrees. This gives the sensor an effective field of view of 8x5 = 40 degrees. The thermopile array is attached to a rotating servo such that the sensor can detect objects around the entire 180 degree field of view. A simple program utilized this arrangement to track a single object moving in a room. The final design will utilize this sensor to get an accurate location of the moving human(s). ===== Ultrasonic PING))) Sensor ===== ^ [[photos|Photo Galleries]] ^ | [[Gallery-PIR|{{:gallery:dscn3002.jpg?150|}}]] | | [[Gallery-PIR|PIR Amplifier]] |

Back to top