A wireless accelerometer system with wavelet analysis for assessing lameness in cattle

A wireless three-dimensional accelerometer system for measuring gait features in dairy cows has been designed and constructed. Eleven Ayrshire dairy cows were selected; based on their locomotion scores, 5 were sound and 6 lame. The four accelerometers were fitted to each limb of the cows proximal to the fetlock joints. The accelerometers used a wireless 869 MHz radio channel for transmitting the acceleration data, measured at 25 Hz with a sensitivity of 6 g. The data were logged to a computer in real time via a receiver. The variance and wavelet variance for each axis and the total acceleration for each leg were calculated, and differences in the symmetry of variance of the hind legs of forward acceleration during the gait of lame and sound cows were determined from the accelerometer data. In addition, the wavelet variance of the lame cows showed differences on level 1 wavelet detail, associated with changes over a 40 ms time scale (i.e. mainly the stage when the leg hits the ground).