Target monitoring system with lens cleaning device

A camera capturing images of a rear vehicle scene and a controller to monitor image quality and issue a lens cleaning command when image quality falls below a threshold. Also disclosed is a system where a camera captures images of the rear vehicle scene containing a trailer attached to the vehicle, a device configured to remove contaminants on a camera lens and controller to analyse the images and activate the lens cleaning based on image quality and trailer motion relative to the vehicle. A rate of image degradation due to the presence of contaminants, such as rain, snow, ice, dirt, dust or debris, on the lens may be determined by analysing edge contrast along lines of images. The system may predict when lens cleaning is required based on rate of image degradation. When reversing or parking it may also predict when towed trailer (or caravan) will reach a maximum hitch angle relative to vehicle based on the images, to avoid a jackknife. If both predictions will occur at the same or similar times, the lens cleaner may be activated before reaching maximum hitch angle. The lens cleaner may include a lens sprayer, lens wiper, lens blower or lens agitator.