Future exploration rovers will be equipped with substantial onboard autonomy. SLAM is a fundamental part and has a close connection with robot perception, planning, and control. The community has made great progress in the past decade by enabling real-world solutions and is addressing important challenges in high-level scalability, resources awareness, and domain adaptation.A novel adaptive SLAM system is proposed to accomplish rover navigation and computational demands. It starts from a three-dimensional odometry dead reckoning solution and builds up to a full graph optimization that takes into account rover traction performance. A complete kinematics of the rover locomotion system improves the wheel odometry solution. In addition, an odometry error model is inferred using Gaussian processes (GPs) to predict nonsystematic errors induced by poor traction of the rover with the terrain. The nonparametric GP regression serves to adapt the localization and mapping to the current navigation demands (domain adaptation). The method brings scalability and adaptiveness to modern SLAM. Therefore, an adaptive strategy develops to adjust the image frame rate (active perception) and to influence the optimization backend by including high informative keyframes in the graph (adaptive information gain). The work is experimentally verified on a representative planetary rover under a realistic field test scenario. The results show a modern SLAM systems that adapt to the predicted error. The system maintains accuracy with less number of nodes taking the most benefit of both wheel and visual methods in a consistent graph-based smoothing approach.
K E Y W O R D Smapping, planetary robotics, position estimation
INTRODUCTIONThe navigation system is a technological key aspect in mobile planetary robots (i.e., rovers). The system allows to know where the rover is, locate the target, and then guide the robot. These three tasks are essential to perform in situ mission operations in the harsh of a remote environment. The navigation system in spacecraft terminology divides into three capabilities as guidance, navigation, and control (GNC). Guidance is the path-planning responsibility. Navigation is the localization and mapping competency, and control is the commanding of the rover locomotion system. These three elements depend on the mission and the requirements affect their design. These requirements are of three types: operational, functional, and resources. Operational imposes the level of autonomy due to a constrained communication bandwidth in space. Functional requirements define the level of performance. Resources establish the sensor type, perception, computational power, and software restrictions.Figure 1a shows a typical GNC system diagram with Simultaneous Localization and Mapping (SLAM) frontend and backend together with the onboard computation demands. Figure 1b depicts the system in two parts. During the first part, the rover acquires images from the navigation cameras, computes a dense map of the surroundings, and calculates t...