Development of an Autonomous Path Tracking Forest Machine - a status report

In many respects traditional automation in the forest-machine industry has reached an upper limit, since the driver already has to deal with an excess of information and take too many decisions at a very high pace. To further automation still, introduction of semi-autonomous and autonomous functions are expected and considered necessary. This paper describes an ongoing project along these ideas. We describe the development of the hardware and software of an unmanned shuttle that shifts timber from the area of felling to the main roads for further transportation. A new path-tracking algorithm is introduced, and demonstrated as being superior to standard techniques, such as Follow-the-Carrot and Pure-Pursuit. To facilitate the research and development, a comprehensive software architecture for sensor and actuator interfacing is developed. Obstacle avoidance is accomplished by a new kind of radar, developed for and by the automotive industry. Localization is accomplished by a Kalman filter combining data from a Real-Time Kinematic Differential GPS/GLONASS and a gyro/compass. Tests conducted on a simulator and a small-scale robot show promising results. Tests on the real forest machine are ongoing, and will be completed before the end of 2005. This paper describes an ongoing project of the design and development of an autonomous path-tracking forest machine. This kind of product is part of a long-term vision in the forest industry [3], of developing an unmanned shuttle that transports timber from the felling area to the main roads for further transportation. The main advantages with such a solution are lower labor costs and less ground damages and emissions due to the lower weight of an unmanned vehicle (the cabin alone weighs several tons). The general requirements and conditions for the development of this kind of product are not addressed in this paper. It focuses instead on one of the necessary components: autonomous navigation, which involves sensing and moving safely along a user-defined path in a dynamic forest environment. Unmanned vehicles in off-road use have been for long an active area of research and development. The mining company LKAB has been using vehicles in underground mines for many years, with reflective markers to aid the laser-based navigation system. Due to safety reasons combined with high demands on availability, these systems are no longer in full commercial operation. Stentz et.all develop optical techniques for localization of underground coal mining machines in [15]. Localization techniques of autonomous forest machines based on a combination of odometry …