Experimental evaluation of automatically-generated behaviors for USV operations. (15th September 2015)

• Record Type: Journal Article
• Authors: Bertaska, Ivan R.; Shah, Brual; von Ellenrieder, Karl; Švec, Petr; Klinger, Wilhelm; Sinisterra, Armando J.; Dhanak, Manhar; Gupta, Satyandra K.
• Is Part Of: Ocean engineering. Volume 106(2015)
• Page Start: 496
• Page End: 514
• Publication Date: 2015-09-15
• Subjects: Marine vehicles -- Unmanned surface vehicles -- COLREGs -- Guidance, navigation and control -- Lattice-based trajectory planning -- Nonlinear control; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2015.07.002
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: The performance of four automatically-generated path planning behaviors is evaluated through field-testing. Experiments were conducted using a model-referenced trajectory planner, which was implemented on unmanned surface vehicles (USVs) of different size, thrust, and maneuverability characteristics. The planner combines a local search based on the Velocity Obstacles (VO) concept with a global, lattice-based search for a dynamically feasible trajectory (determined using models of the nonlinear dynamics, nonholonomic constraints, and low-level control of each system). Multiple low-level USV heading and speed controllers, varying in complexity from proportional control to nonlinear backstepping control, were tested with the planner. High planning performance is achieved by searching within a resolution-adaptive space of the USV׳s candidate motion goals. Sampling is constrained to ensure that the International Regulations for the Prevention of Collisions at Sea (COLREGs) are followed. Prior to on-water implementation, the system was fine-tuned in simulation. Four automatically-generated USV behaviors were demonstrated in on-water tests within a complex, static obstacle field: 1) Approach (USV approaches a fixed target); 2) Follow (USV approaches a moving target); 3) Single COLREGs-Compliant Crossing (USV approaches a fixed target while avoiding another vessel); and 4) Multiple COLREGs-Compliant Crossings (USV approaches a fixed target while avoiding an interference vessel multiple times). Highlights: Four automatically generated behaviors are field tested on two USV platforms. USVs autonomously navigate obstacles and moving vessels while following COLREGs. Linear and nonlinear backstepping low-level USV speed/heading controllers tested. Generalized Velocity Obstacles planner incorporates vehicle and controller dynamics. Adaptive sampling used to make path planner computationally efficient.