Measuring the mobility parameters of forwarders using GPS and CAN bus techniques

Use of a datalogger connected to the CAN bus of an 8-wheeled forwarder’s hydrostatic transmission permits measurement of the gross power on the driveline and the rotational velocity of the drive axle. The ground velocity and trajectory of the forwarder is monitored by the GPS technique. These data allow the total resistance force and wheel slip to be determined under different terrain conditions. In this paper the total resistance force is segregated into rolling, slope and winding resistances. The measuring system was tested in practice on an even tarmac surface and a gently sloping hard earth road, the number of input variables in the first tests having been reduced. It was found that the measuring accuracy permitted detection of about a half percent variation in slope inclination in the test lane. Tests on a figure of 8 track showed that the winding resistance can also be detected. It was concluded that the measuring technique is accurate enough for terramechanical research and practicable under real forestry conditions.