Research on Adaptive Fault-Tolerant Control for Manned Lunar Rover

Since the lunar terrain conditions are very hummocky, there is a risk of simultaneous failure of multiple drive motors and steering motors for manned lunar rover throughout the maneuver. An adaptive fault-tolerant control method based on direct yaw-moment control is proposed to ensure that the rover can still drive stably and accomplish the detection mission despite multi-motor failures. The method adopts a hierarchical control architecture, where the upper layer solves the vehicle’s yaw moment demand based on the astronaut’s driving intention and vehicle condition, and the lower layer carries out torque allocation by introducing failure factor to represent the motor failure situation. Meanwhile, the objective function is designed by combining longitudinal drive control, yaw moment control and tire load rate control, and is adjusted by slip rate to restrain tire slip. Through the joint simulation experiments, the effectiveness of the proposed method is verified. The results show that the driving stability and vehicle maneuverability are guaranteed even in the event of multi-motor failures.

1 Introduction

As the core component of manned lunar exploration, manned lunar rover is designed with high-speed and large-range mobility, so that the astronauts can complete exploration tasks safely and efficiently over longer periods and greater ranges [1, 2]. However, the lunar surface environment is quite complex, covered with rocks, craters and other terrain obstacles of different sizes, and sometimes these obstacles are difficult to identify under the influence of illumination. In addition, the lunar surface is covered with a layer of soft, loose soil, causing serious dust raising when driving at high speed [3, 4]. In such a harsh driving environment, both the drive motors and the steering motors have a certain risk of failure. Fortunately, the manned lunar rover is a typical distributed drive electric vehicle, and the drive motor of each wheel is independently controllable, and the steering motor of the front and rear axles is independently controllable, so there is a high control redundancy for fault-tolerant control. In the case of multimotor failures, the mobility can still be guaranteed by optimizing the driving torque and active-steering system of normal wheels.