Ultrasonic sensor system in a vehicle for terrain identification

A system for use in a vehicle for determining an indication of the type of terrain in the vicinity of the vehicle, the system comprising;

• a processor arranged to receive acoustic sensor output data from at least one vehicle-mounted acoustic sensor, the or each acoustic sensor being arranged to receive a reflected signal from the terrain in the vicinity of the vehicle, and
• a data memory arranged to store pre-determined data relating at least one acoustic parameter to a particular terrain type;
• wherein the processor is arranged to divide the received acoustic sensor output data into at least two data sets, each set corresponding to acoustic signals reflected from a different section of the terrain in a longitudinal direction ahead of the vehicle, and calculate at least one acoustic parameter for each data set in dependence on the received acoustic sensor output data of that set, and
• wherein the processor is arranged to compare the acoustic parameters with the pre-determined data to determine an indication of the particular terrain type based on the acoustic sensor output data only.