Guidance and steering control systems that are now in widespread use by farmers for ploughing and cultivating the land with unprecedented accuracy, require centimetre-level position as well as attitude information accurate to a few degrees. Additionally, position and attitude update rate of no less than 10Hz is required for successful guidance in agricultural environments. Guidance and steering control systems rely particularly on heading and roll measurements to steer the tractor on parallel straight lines or curves known as plough lines.