Harris, L. R. and Jenkin, M. The effect of blur on the perception of up. Optometry and Vision Science 91: 103-110, 2014.
Knowing one's orientation relative to the environment is important for many aspects of vision including object recognition, action planning and balance. Here we assess how inadequate optical correction for typical refractive rrors might influence this. We measured the effect of blur on the perception of orientation as measured by the subjective visual vertical (SVV) and the perceptual upright (PU).
Yang, J., Dymond, P. and Jenkin, M. Integrating multiple soft constraints for planning practical paths. Proc. IEEE/RSJ IROS. Chicago, IL, 2014.
Sampling-based algorithms are a common ap- proach to high-dimensional real-world path planning problems. Unfortunately the solutions found using such planners are often not practical in that they do not take into account soft application-specific constraints. This paper formulates the practicality of paths based on the notion of soft constraints found in the Planning Domain Definition Language 3 (PDDL3) [21] and a range of optimization strategies are developed targeted towards user-preferred qualities by integrating soft constraints in the pre-processing, planning and post-processing phases of the sampling-based path planners. An auction-based resource allocation approach coordinates competing optimization strategies. This approach uses an adaptive bidding strategy for each optimizer and in each round the optimizer with the best predicted performance is selected. This general coordination system allows for flexibility in both the number and types of the optimizers used. Experimental validation demonstrates the effectiveness of the approach.
Codd-Downey, R., Mojiri Forooshani, P., Speers, A., Wang, H. and Jenkin, M. From ROS to Unity: leveraging robot and virtual environment middleware for immersive teleoperation. Proc. IEEE Int. Conf. on Information and Automation (ICIA). Hailar, China.
Virtual reality systems are often proposed as an appropriate technology for the development of teleoperational interfaces for autonomous and semi-autonomous systems. In the past such systems have typically been developed as “one off†experimental systems in part due to a lack of common software systems for both robot software development and virtual environment infrastructure. More recently, common frameworks have begun to emerge for both robot control (e.g., ROS) and virtual environment display and interaction (e.g., Unity). Here we consider the task of developing systems that integrate these two environments. A yaml-based communications protocol over web sockets is used to glue the two software environments together. This allows each system to be controlled using standard software toolkits independently while providing a flexible interface between these two infrastructures.
Codd-Downey, R., Jenkin, M. and Speers, A. Building a ROS node for a NMEA depth and temperature sensor. Proc. 11th Int. Conf. on Informatics in Control, Automation and Robotics (ICINCO), Vienna, Austria.
Although many commercially available robots ship with a version of ROS this is not as true for many external sensors. There is a lack of ROS support for many devices and sensors one might use to extend the capabilities of a robot. As robots are deployed in more complex environments there is the need for more specialized sensors. In particular in the aquatic domain there is the need for support for depth sounders. This paper describes the design and construction process for building a ROS node for a NMEA 0183 compliant depth and temperature transducer and a strategy for extending this design to other NMEA devices.A copy of the poster presented at the conference is available here.
Harris, L. R., Herpers, R., Hofhammer, T. and Jenkin, M. How much gravity is needed to establish the perception of upright? PLoS ONE 9(9): e106207.
Might the gravity levels found on other planets and on the moon be sufficient to provide an adequate perception of upright for astronauts? Can the amount of gravity required be predicted from the physiological threshold for linear acceleration? The perception of upright is determined not only by gravity but also visual information when available and assumptions about the orientation of the body. Here, we used a human centrifuge to simulate gravity levels from zero to earth gravity along the long-axis of the body and measured observers' perception of upright using the Oriented Character Recognition Test (OCHART) with and without visual cues arranged to indicate a direction of gravity that differed from the body's long axis. This procedure allowed us to assess the relative contribution of the added gravity in determining the perceptual upright. Control experiments off the centrifuge allowed us to measure the relative contributions of normal gravity, vision, and body orientation for each participant. We found that the influence of 1 g in determining the perceptual upright did not depend on whether the acceleration was created by lying on the centrifuge or by normal gravity. The 50% threshold for centrifuge-simulated gravity's ability to influence the perceptual upright was at around 0.15 g, close to the level of moon gravity but much higher than the threshold for detecting linear acceleration along the long axis of the body. This observation may partially explain the instability of moonwalkers but is good news for future missions to Mars.
Wang, H, Jenkin, M. and Dymond, P. Deterministic topological visual SLAM. Proc. ACM Symposium on Information and Communication Technology. Hanoi, Vietnam, 2014.
Simultaneous Localization and Mapping (SLAM) addresses the task of building a map of the environment with a robot while simultaneously localizing the robot relative to that map. SLAM is generally regarded as one of the most important problem in the pursuit of building truly autonomous mobile robots and is typically expressed within a probabilistic framework. A probabilistic framework allows for the representation of multiple world and pose models required due to the lack of a deterministic solution to the SLAM problem. But is it possible to solve SLAM deterministically? In [18] it was shown that given a unique fixed directional marker that provides a single unique location with orientation information, SLAM can be solved deterministically for topological environments. But this solution is theoretical in nature and its underlying assumptions have not been validated using a real platform. Here we demonstrate a deterministic solution to SLAM for corridor-like environments using a robot equipped with an omni-directional video sensor.
Kapralos, B., Larn, J., Collins, K., Hogue, A., Kanev, K. and Jenkin, M. Sound localization on tabletop comptuers: a comparison of two amplitude panning methods.ACM Computers in Entertainment (CIE) 12: 1-19, 2014.
Tabletop computers (also known as surface computers and smart tables) have been growing in popularity for the past decade and are poised to make inroads into the consumer market, opening up a new market for the games industry. But before tabletop computers become widely accepted, there are many questions with respect to sound production and reception for these devices that need to be explored, particularly when it comes to multimedia consumption on the devices. For example, which loudspeaker setups should be used to take into consideration the multi-user nature of tabletop computers, and which panning method(s) maximize the spatial localization abilities of the user(s)? Previous work suggests that a quadraphonic diamond-shaped loudspeaker configuration--whereby a loudspeaker is placed at each of the four sides of the tabletop computer-leads to more accurate localization results when compared with a traditional quadraphonic loudspeaker configuration--whereby a loudspeaker is placed at each of the four corners of the tabletop computer. Given this preference for a diamond loudspeaker configuration, we examine two amplitude-panning methods (bilinear interpolation and inverse distance) for spatializing a sound on the (horizontal) surface of the table-computer with a diamond loudspeaker configuration. Results from the study detailed in this paper indicate that there are no significant differences between the two methods and that both methods are prone to error.
