A novel remote measurement and monitoring system for the measurement of critical washing parameters inside a domestic washing machine

Abstract

A patented measurement system has been developed and tested that allows the remote sensing of critical wash parameters directly inside a domestic washing machine via a wireless data acquisition system. The system continuously measures and monitors local flow velocity within the wash load but can easily be adapted to suit or extrapolate other parameters, e.g. shear stress, temperature, humidity etc. The flow measurements are obtained from a peculiar form of the well-tested Pitot tube-probe combined with a piezoresistive type pressure transducer and a matched pair of battery operated 433 MHz hybrid transmitters and receivers. The probe, which is located on the surface of a hollow sphere, captures local dynamic pressure, which can be related to the surface flow velocity. The transducer and transmitter are housed within the sphere that was designed to follow the wash load during the washing cycle and using rapid prototyping technology for its realisation. The receiver, that is mounted outside the machine, picks up the modulated radio signal after which it is processed and stored using a dedicated data acquisition system. This D.A. system is based on a sample-and-hold board, a PCMCIA card and program developed using LABVIEW software. The use of the same probe installed on the inside surface of the washing machine door face and relative experimental results are also discussed.