Abstract-We provide a unified probabilistic framework for trajectory estimation and planning. The key idea is to view these two problems, usually considered separately, as a single problem. At each time-step the robot is tasked with finding the complete continuous-time trajectory from start to goal. This can be quite difficult; the robot must contend with a potentially high-degreeof-freedom (DOF) trajectory space, uncertainty due to limited sensing capabilities, model inaccuracy, and the stochastic effect of executing actions, and the robot must find the solution in (faster than) real time. To overcome these challenges, we build on recent probabilistic inference approaches to continuous-time localization and mapping and continuous-time motion planning. We solve the joint problem by iteratively recomputing the maximum a posteriori trajectory conditioned on all available sensor data and cost information. Finally, we evaluate our framework empirically in both simulation and on a mobile manipulator.
I. INTRODUCTION & RELATED WORKTrajectory estimation and planning are both important capabilities for autonomous robot navigation. Trajectory estimation is fundamentally backward-looking: the robot estimates a trajectory of previous states that are consistent with a history of noisy and incomplete sensor data. Conversely, planning is fundamentally forward looking: starting from an estimate of its current state, the robot optimizes a trajectory of future states to minimize a cost function and achieve a feasible solution.In this paper, we provide a unified approach to trajectory estimation and planning. The key idea is to view these two problems, usually considered separately, as a single problem. At each time-step the robot is tasked with finding the complete continuous-time trajectory from start to goal. This can be quite difficult; the robot must contend with a potentially highdegree-of-freedom (DOF) trajectory space, uncertainty due to limited sensing capabilities, model inaccuracy, and the stochastic effect of executing actions, and the robot must find the solution in (faster than) real time.To overcome these challenges, we build on recent probabilistic inference approaches to continuous-time localization and mapping and continuous-time motion planning. We solve the joint problem by iteratively recomputing the maximum a posteriori (MAP) trajectory conditioned on all available sensor data and cost information. In brief, we represent continuoustime trajectories as samples from a Gaussian process (GP) [5,22] and then formulate the estimation and planning problem on a single probabilistic graphical model. We perform inference on the graph using numerical tools that solve a nonlinear least squares optimization problem, and generate fast, iterative solutions by exploiting the structure of the problem.