Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Karol Hausman, Gregory Kahn, Sachin Patil, Joerg Mueller, Ken Goldberg, Pieter Abbeel, Gaurav Sukhatme University of Southern California, University of California Berkeley
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions
Belief Space Planning Perception Action Belief Space Planning State space plan start goal Problem settingBelief space plan [Example from Platt et al., 2010] This is a Partially Observable Markov Decision Process (POMDP) – in general intractable
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Belief Space Planning State space plan start goal Problem settingBelief space plan [Example from Platt et al., 2010]
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Belief Space Planning Nonlinear stochastic motion and observation models Belief space: Convert underlying dynamics to belief space dynamics Bayesian filter (e.g., Extended Kalman Filter (EKF)) (state space) x (belief space)
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Belief Space Planning Minimize Constraints: = goal Measurements?
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Belief Space Planning Minimize Constraints: = goal Maximum likelihood measurements
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Level -1 Level 0 Level 1 Level 2 [Hausman et al., ISER 2014, IJRR 2015] Occlusions
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Occlusions Field of view (FOV) discontinuity Occlusion discontinuity
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Occlusions : Binary variable {0,1} 0 -> No measurement 1 -> Measurement Modified Kalman Gain in EKF: [Patil et al. ICRA 2014] Binary non-convex optimization problem – difficult to solve!
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Occlusions ≈
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Occlusions Increasing difficulty [Patil et al. ICRA 2014]
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Occlusions Outside camera FOV Occlusions due to other quadrotors [Hausman et al., ICRA 2016]
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Consider nonlinear stochastic dynamics and measurement models Dynamics: Measurement: Problem formulation
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Problem formulation Cost terms:
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Results
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Results Thank you How does the optimization time horizon affect tracking performance? 2 time steps5 time steps10 time steps Avg. over 10 runs
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Results Thank you How does number of quadrotors affect tracking performance? 1 quadrotor3 quadrotors5 quadrotors
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Results Thank you How does optimization compare to random sampling or lattice based sampling in terms of tracking performance? Random samplingLattice samplingOptimization 3 Quadrotors
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Results How does explicit consideration of occlusions affect tracking performance? Does not consider occlusions during planning Consider occlusions during planning
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Results Multi-level topology approach (Hausman et al, 2014) Optimization Comparison of topology approach vs. optimization
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Insights
Optimization-Based Cooperative Multi-Robot Target Tracking with Reasoning about Occlusions Summary 3D Tracking Approach: considers onboard sensing and does not need to explicitly reason about sensing topologies is probabilistic and takes into account motion and sensing uncertainties provides locally optimal control in 3D
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