The LiDAR Compass: Extremely Lightweight Heading Estimation with Axis Maps

This paper introduces the LiDAR compass, a bounded and extremely lightweight heading estimation technique that combines a two-dimensional laser scanner and axis maps, which represent the orientations of flat surfaces in the environment. Although suitable for a variety of indoor and outdoor environments, the LiDAR compass is especially useful for embedded and real-time applications requiring low computational overhead. For example, when combined with a sensor that can measure translation (e.g., wheel encoders) the LiDAR compass can be used to yield accurate, lightweight, and very easily implementable localization that requires no prior mapping phase. The utility of using the LiDAR compass as part of a localization algorithm was tested on a widely-available open-source data set, an indoor environment, and a larger-scale outdoor environment. In all cases, it was shown that the growth in heading error was bounded, which significantly reduced the position error to less than 1% of the distance travelled.

Assessing the Impact of Shipping Vessel Noise on Humpback Whales

The ocean is a hub of noise. Bioacoustic noise, noise from precipitation and wind, and noise from oceanic shelf slides and other geologic processes have occurred consistently as marine species have evolved over time. However, with the discovery of oceanic oil and gas reserves, submarine systems, ship propulsion and the emergence of global trade, anthropogenic sources of sound have added significant quantities of sound to the oceanic system. Shipping has been found to be the largest input of low-frequency anthropogenic noise and Humpback Whales (Megaptera novaengliae), known to be the most vocal marine species, have an auditory sensitivity that falls within the range of frequencies emitted by shipping vessels. As Humpback Whales are heavily dependent on vocalizations, for reasons relatively unconfirmed, a better understanding of why they sing and how their communication is being impacted by vessel noise is critical. Evaluating existing literature both on Humpback behavior and communication, the mechanics of their communication, sound emissions from modern ships, oceanic sound transmission, and studies regarding Humpback's exposure to other sources of low-frequency anthropogenic noise, it is clear that more research is needed to draw any causational conclusions between vessel noise and detrimental impacts on Humpback Whales. With a projected increase in global consumption and vessel traffic, there is an urgent need for further research exploring shipping noise impacts and behavioural alterations of Humpbacks. Existing research has shown changes in Humpback communication when exposed to low-frequency sonar noise, however few studies have been conducted on their communication when in close proximity to shipping vessels. In order for the impacts to be properly assessed, preliminary understanding of humpback communication, their auditory thresholds and more studies between vessel noise exposure and Humpback Whale behavior must be conducted.

Estimating the Heading of a Husky Mobile Robot with a LiDAR Compass based on Direction Maps

Without an absolute position sensor (e.g., GPS), an accurate heading estimate is necessary for proper localization of an autonomous unmanned vehicle or robot. This paper introduces direction maps (DMs), which represent the directions of only dominant surfaces of the vehicle’s environment and can be created with negligible effort. Given an environment with reoccurring surface directions (e.g., walls, buildings, parked cars), lines extracted from laser scans can be matched with a DM to provide an extremely lightweight heading estimate that is shown, through experimentation, to drastically reduce the growth of heading errors. The algorithm was tested using a Husky A200 mobile robot in a warehouse environment over traverses hundreds of metres in length. When a simple a priori DM was provided, the resulting heading estimation showed virtually no error growth.