A Reconfigurable Test Platform For Developing Autonomous articulated Pendulum-Arm Suspension Forest Machines

Forest machines travel over rough and rocky terrain and the drivers suffer intensive whole body vibrations. Moreover, the heavy weight of the machine often damages soils and plants in the nature environment, which makes the forest industry less sustainable. Autonomous forest machines that can evenly distribute ground pressure and be remotely supervised are emerging solutions. The development of such vehicles requires not only simulations but also physical experiments. A scaled-down test platform emulating the real forest machine significantly reduces the development cost and improves safety. The machine studied in this paper is an articulated forwarder with six wheels mounted on six pendulum-arms. The angles of the pendulum-arms are controlled individually to balance the tire pressure and keep the chassis horizontal. To date, there is no affordable test platform with the same vehicle design. This paper elaborates the mechanical structure and electronics of the design of such a scaled-down test platform. The test platform is reconfigurable in both mechanical structure and the electronics. Its chassis has three sections connected by two actuated joints. Through the control on the two joints, the vehicle can be configured as two or three body sections. The usage of ROS middleware and the design of the electronic architecture allow easy reconfiguration of perception sensors and control actuators. The test platform uses a master-slave architecture of embedded controllers. The master controller is an on-board embedded computer running Linux. The slave controllers implement dedicated functions on perception, control and communication. The platform has a dedicated router to enable remote access to the system. Each pendulum-arm is controlled by a linear actuator and each wheel is controlled by a BLDC motor. The positions of the six arms are simultaneously coordinated by the master controller, so that the vehicle can travel on uneven terrain with higher speed, less cabin vibration, and a more horizontal chassis. The contribution of this paper is the detailed instruction on the design and manufacturing of a 1:5 scaled-down model of a forest forwarder, which can autonomously navigate in a forest environment.Part of proceedings: ISBN 978-1-942112-52-5QC 20220215