During volcanic activity, people are restricted from coming within a certain distance to the volcano crater because of the danger posed. However, observing the restricted area is very important to reduce the risk to residents from eruptions such as pyroclastic and debris flows. Therefore, teleoperated mobile robots are being developed to observe conditions in such restricted areas, remotely. However, such volcanic environments include loose soil slopes of volcanic ash and lapillus, which may be impossible to traverse using current mobile robotics technology. Thus, we propose a contact angle control method for a multi-degrees of freedom (DOF) tracked vehicle. This controls the contact angle of the tracks and decreases the potential for the robot to sideslip on loose ground. To evaluate this method, we installed a contact load sensing system in each tracks. The effectiveness of the method was verified on an indoor simulated volcanic field and an outdoor field. In this paper, we explain the proposed method, introduce our developed robot and sensing system, and report the results of our evaluation experiments.