Remote measurement and monitoring of critical washing process data directly inside the washing machine drum

The system proposed allows the remote sensing of pressure inside the wash load of a domestic washing machine via a wireless data acquisition system. The system is based on a piezoresistive pressure transducer and a matched pair of battery operated hybrid transmitters and receivers with a working frequency of 433 MHz. The transducer and transmitter are housed within a small plastic sphere designed to follow the wash load during its movement in the washing machine drum. A small block probe is fitted to the surface of the sphere to pick up the surface dynamic pressure of the sphere and relate this to the local surface velocity. The receiver is mounted on the outside of the washing machine where it picks up the modulated signal from the transmitter and stores it through a dedicated data acquisition system. The system has been designed to offer the maximum flexibility and is therefore applicable to many other remote sensing circumstances including those outside domestic appliances.