SLAMBooster: An Application-aware Controller for Approximation in SLAM

Simultaneous Localization and Mapping (SLAM) is the problem of constructing a map of an agent's environment while localizing or tracking the mobile agent's position and orientation within the map. Algorithms for SLAM have high computational requirements, which has hindered their use on embedded devices. Approximation can be used to reduce the time and energy requirements of SLAM implementations as long as the approximations do not prevent the agent from navigating correctly through the environment. Previous studies of approximation in SLAM have assumed that the entire trajectory of the agent is known before the agent starts to move, and they have focused on offline controllers that use features of the trajectory to set approximation knobs at the start of the trajectory. In practice, the trajectory is not usually known ahead of time, and allowing knob settings to change dynamically opens up more opportunities for reducing computation time and energy. We describe SLAMBooster, an application-aware online control system for SLAM that adaptively controls approximation knobs during the motion of the agent. SLAMBooster is based on a control technique called hierarchical proportional control but our experiments showed this application-agnostic control led to an unacceptable reduction in the quality of localization. To address this problem, SLAMBooster exploits domain knowledge: it uses features extracted from input frames and from the estimated motion of the agent in its algorithm for controlling approximation. We implemented SLAMBooster in the open-source SLAMBench framework. Our experiments show that SLAMBooster reduces the computation time and energy consumption by around half on the average on an embedded platform, while maintaining the accuracy of the localization within reasonable bounds. These improvements make it feasible to deploy SLAM on a wider range of devices.