Making the Milrem Themis UGV ready for autonomous operations

The usage of Unmanned Ground Vehicles (UGVs) in defence application is increasing, and much research effort is put into the field. Also, many defence vehicle producers are developing UGV platforms. However, the autonomy functionality of these systems are still in need of improvement. At the Norwegian Defence Research Establishment a project for developing an autonomous UGV was started in 2019 and use a Milrem THeMIS 4.5 from Milrem Robotics as the base platform for achieving this. In this paper we will describe the modifications made to the vehicle to make it ready for autonomous operations. We have added three cameras and a Lidar as vision sensors, for navigation we have added a GNSS, IMU and velocity radar, and all sensors get a common time stamp from a time server. All the sensors have been mounted on a common aluminium profile, which is mounted in the front of the vehicle. The vision and navigation sensors have been mounted on the common aluminium profile to ensure that the direction the vision sensors observe is known with as little uncertainty as possible. In addition to the hardware modification, a control software framework has been developed on top of Milrem’s controller. The vehicle is interfaced using ROS2, and is controlled by sending velocity commands for each belt. We have developed a hardware abstraction module that interfaces the vehicle and adds some additional safety features, a trajectory tracking module and a ROS simulation framework. The control framework has been field tested and results will be shown in the paper.