Week 7

Week 6 included of a lot of research of our inputs and we decided to finally choose, Seat Occupancy Sensor, Seat Belt Sensor and Vehicle Speed Sensor for our project.

1) Seat Belt Sensor - the seat belt sensor works using a Reed Switch which is triggered when the metal tongue side of the buckle is inserted into the main buckle housing, then the sensor and the magnet on the tongue become magnetically isolated by changing the state of contact. This in turn transports the switching or the sensing function. Where as during the disengagement of the seat belt tongue and the buckle housing, the interference no longer exists and the reed sensor contact returns to the reset mode. A .gif format image is shown below of how it works

2) Vehicle Speed Sensor - A Vehicle Speed Sensor is used in many performance enhancing electronic systems in the car such as ABS, Cruise Control and traction control to name a few. More systems in which this used was explained in our demonstration. They're usually gear driven, found on the transmission case or differential assembly and measures transmission output speed. A Vehicle Speed sensor uses components such as 2 hall effect sensors, a rare earth magnet and appropriate evaluation electronics.

Image shown below.

3) Seat Occupancy Sensor - A Seat occupancy sensor consists of a flexible sensor mat which is inserted into the vehicle seat. The mat consists of two sandwiched carrier sheets held together. An increase in pressure on the mat will cause change in electrical resistance which informs the system whether the seat is occupied or not. The occupancy on the seat is only detected for weights higher than the 40kgs, this depends on manufacturer's specifications.