Mirrored Light Field Video Camera Adapter

This paper proposes the design of a custom mirror-based light field camera adapter that is cheap, simple in construction, and accessible. Mirrors of different shape and orientation reflect the scene into an upwards-facing camera to create an array of virtual cameras with overlapping field of view at specified depths, and deliver video frame rate light fields. We describe the design, construction, decoding and calibration processes of our mirror-based light field camera adapter in preparation for an open-source release to benefit the robotic vision community.Comment: tech report, v0.5, 15 pages, 6 figure

withdrawn 2017 hrs ehra ecas aphrs solaece expert consensus statement on catheter and surgical ablation of atrial fibrillation

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Autonomous vision-based docking of the tethered axel rover for planetary exploration

Some of the most interesting scientific targets for future planetary exploration missions are located in terrain inaccessible to state-of-the-art rover technology, such as exposed impact craters and the Skylight holes on Mars. In order to explore this extreme terrain, the Axel rover has been proposed. It is a two-wheeled tethered robot capable of rappelling steep slopes and traversing rocky terrain. For untethered mobility between scientific targets, two Axel rovers combine and dock with a central module to form the DuAxel rover. Tele-operation of the docking and undocking process of the Axel rovers from the central module has been achieved, but it is a time-consuming process that must be accomplished autonomously for practical space operations. This master's thesis details the development of a vision-based algorithm to enable autonomous docking and undocking of the Axel rover to or from the DuAxel rover, following the anchoring of the central module. The algorithm was field tested in the JPL Mars Yard. The proof-of-concept algorithm was able to successfully dock 29 out of 40 tests that were designed to push the algorithm to its limits. The docking range is 5m- 6m and was tested successfully up to 40°, radially centered about the central module, with a relative heading of +-20° to the central module. Although many minor improvements can be made, there are no major challenges to the docking algorithm to demonstrate safe and reliable autonomous capabilities for missions in extreme terrain mobility and exploration

Light-field features for robotic vision in the presence of refractive objects

Curved transparent objects are difficult for robots to perceive and this makes it difficult for robots to work with them. This thesis shows that multi-aperture or light-field cameras overcome this problem since they capture a set of dense and uniformly sampled views to capture multiple views of the scene. The advances constitute a critical step towards enabling robots to work more safely and reliably with everyday refractive objects

Inverse two-player zero-sum dynamic games

In this paper, we consider the problem of inverse dynamic games: given the observed behaviour of players during a dynamic game in equilibrium, how can we determine the underlying objective functions of the game? Whereas previous work in the literature has focused on inverse static games, our work focuses on inverse dynamic games. In particular, we address the problem of estimating the unknown parameters of the objective function of a two-player zero-sum dynamic game in open-loop Nash equilibrium. We exploit necessary conditions for equilibrium in a two-player zero-sum dynamic game to develop sufficient conditions for solving the two- player zero-sum inverse dynamic game problem. The sufficient conditions hold under assumptions on the control constraints and convexity of the game dynamics, and transform the inverse two-player zero-sum dynamic game problem into the problem of solving a system of linear equations. We apply our results to a linear quadratic two-player zero-sum game, and illustrate the recovery of objective function parameters from state and control equilibrium trajectories

Autonomous vision-based tethered-assisted rover docking

Many intriguing science discoveries on planetary surfaces, such as the seasonal flows on crater walls and skylight entrances to lava tubes, are at sites that are currently inaccessible to state-of-the-art rovers. The in situ exploration of such sites is likely to require a tethered platform both for mechanical support and for providing power and communication. Mother/daughter architectures have been investigated where a mother deploys a tethered daughter into extreme terrains. Deploying and retracting a tethered daughter requires undocking and re-docking of the daughter to the mother, with the latter being the challenging part. In this paper, we describe a vision-based tether-assisted algorithm for the autonomous re-docking of a daughter to its mother following an extreme terrain excursion. The algorithm uses fiducials mounted on the mother to improve the reliability and accuracy of estimating the pose of the mother relative to the daughter. The tether that is anchored by the mother helps the docking process and increases the system's tolerance to pose uncertainties by mechanically aligning the mating parts in the final docking phase. A preliminary version of the algorithm was developed and field-tested on the Axel rover in the JPL Mars Yard. The algorithm achieved an 80% success rate in 40 experiments in both firm and loose soils and starting from up to 6 m away at up to 40° radial angle and 20° relative heading. The algorithm does not rely on an initial estimate of the relative pose. The preliminary results are promising and help retire the risk associated with the autonomous docking process enabling consideration in future martian and lunar missions