Chemical Plume Tracking Research Articles

A planning method for chemical plume tracking and source localization with autonomous underwater vehicle

Underwater target detection technology is an important mean for the development and utilization of marine environment, which has important value in commercial and military fields, and is valued by more and more experts, scholars, and production technicians. A set of behavior-based autonomous underwater vehicle online task planning algorithm is proposed in this article, including the searching behavior based on changing Z-shape, tracking behavior based on an improved artificial potential field theory with likelihood map, rediscovering behavior, and source declare behavior. The proposed algorithm can improve the accuracy and success rate of autonomous underwater vehicle to the source positionficient. The physical experiment results verify the effectiveness of the proposed method.

Active anemosensing hypothesis: how flying insects could estimate ambient wind direction through sensory integration and active movement.

Estimating the direction of ambient fluid flow is a crucial step during chemical plume tracking for flying and swimming animals. How animals accomplish this remains an open area of investigation. Recent calcium imaging with tethered flying Drosophila has shown that flies encode the angular direction of multiple sensory modalities in their central complex: orientation, apparent wind (or airspeed) direction and direction of motion. Here, we describe a general framework for how these three sensory modalities can be integrated over time to provide a continuous estimate of ambient wind direction. After validating our framework using a flying drone, we use simulations to show that ambient wind direction can be most accurately estimated with trajectories characterized by frequent, large magnitude turns. Furthermore, sensory measurements and estimates of their derivatives must be integrated over a period of time that incorporates at least one of these turns. Finally, we discuss approaches that insects might use to simplify the required computations, and present a list of testable predictions. Together, our results suggest that ambient flow estimation may be an important driver underlying the zigzagging manoeuvres characteristic of plume tracking animals’ trajectories.

Chemical plume tracking using an AUV with UKF based extremum seeking

Hydrothermal vent areas are unique ecosystems with high productivity and high biodiversity that are subject to ongoing research. Hydrothermal vents form in areas with increased magmatic activity where superheated, mineral rich water leaks from the seafloor. Due to the rapid cooling of the water the metal sulfides precipitate and form a black or white plume that can be sensed several hundred meters away from the vent source. Finding and reliably following such plumes with autonomous underwater vehicles (AUVs) is a challenging task since the plume does not have a smooth concentration gradient but lots of local patches due to the turbulent particle flow. This paper presents an algorithm that combines biology inspired chemotaxis with Unscented Kalman filter (UKF) based extremum seeking control (ESC). The effectiveness is demonstrated by a simulation of a physics-based AUV model in a turbulent 3D Plume model.

Palm-Sized Quadcopter for Three-Dimensional Chemical Plume Tracking

In this study, we designed and experimentally verified the placement of odor sensors and an algorithm using the aero-olfactory effect of a palm-sized quadcopter to solve the three-dimensional chemical plume tracking (3D-CPT) problem. Solving 3D-CPT is important in engineering as it helps perform rescue operations during disasters and identify sources of harmful substances. Moreover, the odor sensors must be properly located and a CPT algorithm be applied to improve the tracking performance of a chemical. However, studies regarding the use of quadcopters for solving the 3D-CPT problem are scarce, and the relationship between the odor sensor location and algorithm is debatable. Hence, we utilized particle image velocimetry, an airflow visualization technology, to evaluate the arrival direction of chemicals at different heights. The results showed that odor sensors must be placed on the upper and front surfaces of a quadcopter to monitor the chemicals three-dimensionally. Additionally, we designed a 3D surge-casting algorithm, which is an extension of the CPT strategy of a flying moth, that is, surge casting, to accommodate the proposed odor sensor placement. By conducting 3D-CPT experiments based on different heights of odor sources using the proposed system, we discovered that even in an environment with significant changes in the wind direction the CPT performance is better than that of the conventional 3D-CPT algorithm. Thus, 3D-CPT should be further improved to enable its application in unknown and cluttered environments. In this study, we improved the 3D-CPT performance of a palm-sized quadcopter by designing an appropriate sensor arrangement and algorithm balance.

Experimental Analysis of the Influence of Olfactory Property on Chemical Plume Tracing Performance

In this letter, we investigated the relationship between the performance of chemical plume tracing (CPT) and odor sensing property. Tracking of chemical plumes plays an important role because it facilitates the identification of an odor source. Conventional research has focused on the development of CPT algorithms, whereas the influence of the performance odor sensors on CPT performance has not been investigated. Therefore, in this letter, we first compared the olfactory characteristics of an insect (silkworm moth, Bombyx mori ), which has high CPT performance and the characteristics of an artificial odor sensor. In particular, we focused on and compared the recovery times of the two types of sensors, which plays an important role in the acquisition of odor information. As a result, it was determined that the recovery time for the insect olfactory sensor was ten times faster than that of the artificial odor sensor. We also experimentally evaluated the effect of this difference in the recovery time on CPT performance. CPT experiments using silkworm moths and a robot revealed that there was a correlation between the CPT performance and sensor recovery time. As such, it was demonstrated that it is necessary to improve not only the algorithm but also the sensor recovery time to improve the CPT performance.

Tracking and quantification of gaseous chemical plumes from anthropogenic emission sources within the Los Angeles Basin

This paper describes the sensor technology, measurement methodology and data analysis algorithms that are used to characterize gaseous emissions observed with a large-area coverage longwave-infrared (LWIR) hyperspectral imaging (HSI) sensor. In so doing the demonstrated capability is expanded well beyond the small number of gas species that have typically been reported and also sets these observations within a definitive, comprehensive framework that documents in detail the procedures used for detection, identification, and quantification of atmospheric trace gases using LWIR HSI systems, along with the methodology for determining their respective detection limits. Examples are provided for a 530km2 region of the Los Angeles Basin collected on July 22, 2014.

3D Moth-inspired chemical plume tracking and adaptive step control strategy

This paper presents an adaptive-step-control (ASC) strategy for autonomous chemical plume tracking (CPT) in both 2D and 3D spaces. The aim of CPT is tracking a target chemical flow back to its source and declaring its location. While the majority of related works are based on wheeled robots in 2D, the rapid development of rotorcrafts makes 3D plume tracking possible. Hence, in this paper, we first discuss the generalized form of moth-inspired CPT work flow, then extend the orthodox moth-inspired CPT from 2D to 3D. More importantly, we also propose an ASC strategy to deal with the “passing-by” problem and to gain better control performance. Simulation results are given to demonstrate that ASC can solve the inflexibility caused by “hard” step length in diffusive airflow, because it can autonomously adjust the step lengths of the robot according to the status of the environment, enabling our robot to stride confidently in the low chemical concentration areas and focus on highly suspicious areas.

Sustained in situ measurements of dissolved oxygen, methane and water transport processes in the benthic boundary layer at MC118, northern Gulf of Mexico

Within months of the BP Macondo Wellhead blowout, elevated methane concentrations within the water column revealed a significant retention of light hydrocarbons in deep waters plus corresponding dissolved oxygen (DO) deficits. However, chemical plume tracking efforts were hindered by a lack of in situ monitoring capabilities. Here, we describe results from in situ time-series, lander-based investigations of physical and biogeochemical processes controlling dissolved oxygen, and methane at Mississippi Canyon lease block 118 (~18km from the oil spill) conducted shortly after the blowout through April 2012. Multiple sensor arrays plus open-cylinder flux chambers (“chimneys”) deployed from a benthic lander collected oxygen, methane, pressure, and current speed and direction data within one meter of the seafloor. The ROVARD lander system was deployed for an initial 21-day test experiment (9/13/2010–10/04/2010) at 882m depth before a longer 160-day deployment (10/24/2011–4/01/2012) at 884m depth. Temporal variability in current directions and velocities and water temperatures revealed strong influences of bathymetrically steered currents and overlying along-shelf flows on local and regional water transport processes. DO concentrations and temperature were inversely correlated as a result of water mass mixing processes. Flux chamber measurements during the 160-day deployment revealed total oxygen utilization (TOU) averaging 11.6mmol/m2day. Chimney DO concentrations measured during the 21-day deployment exhibited quasi-daily variations apparently resulting from an interaction between near inertial waves and the steep topography of an elevated scarp immediately adjacent to the 21-day deployment site that modulated currents at the top of the chimney. Variability in dissolved methane concentrations suggested significant temporal variability in gas release from nearby hydrocarbon seeps and/or delivery by local water transport processes. Free-vehicle (lander) monitoring over time scales of months to years utilizing in situ sensors can provide an understanding of processes controlling water transport, respiration and the fate and impacts of accidental and natural gas and oil releases.

Autonomous tracking of chemical plumes developed in both diffusive and turbulent airflow environments using Petri nets

This paper presents a Petri net model for autonomous tracking of chemical plumes developed in both diffusive and turbulent airflow environments. It has been challenging to develop a generalized algorithm to effectively trace both types of chemical plumes due to the significant differences of their kinetic and dynamic properties. Our idea is to utilize a Petri net to model the change relationships of chemical concentrations acquired by two sensors mounted on the both sides of a DaNI robot during a tracing process. Because the relationships imply the effects of flow variation on chemical puffs, a flow sensor is eliminated. To express and maintain the knowledge of chemical concentration changes using the Petri net, we design a mapping algorithm for generating the Petri net from production rules. The Petri net model is implemented on the robot using LabVIEW. The chemical plume tracing experiments achieve 93.8% and 87.5% of source localization rates under both turbulent and diffusive airflow environments, respectively.

Modeling and Numerical Simulation Analysis of Chemical Plume in Flow Field

A new discrete chemical plume model based on CFD was established, which avoids the shortcomings of the current model. In this model CFD was applied to simulate the turbulent environment of chemical plume, while the chemical substances contained in the plume were modeled as discrete phase. Utilizing this model, chemical plume under water was simulated numerically and analyzed hereafter. The transport characteristics of simulated plume were consistent with existing experimental results. Based on the simulation results, the effect of flow field on plume transport was also analyzed. The model proves an efficient approach to simulate the transport process in different environment, as well as analyze various types of actual situations. Moreover, this model can provide the theoretical basis for plume tracking algorithm research and simulation platform, which promotes significantly the research on chemical plume tracking.

Bioinspired algorithm for autonomous sensor-driven guidance in turbulent chemical plumes

We designed and implemented a control algorithm for sensor-mediated chemical plume tracking in a turbulent flow environment. In our design, we focused on development of a signal processing strategy capable of replicating behavioral responses of actively tracking blue crabs (Callinectes sapidus) to chemical stimuli. The control algorithm is evaluated in a hardware platform that allows motion in two directions (i.e. forward–back and left–right). The geometric arrangement of the sensor array is inspired by the location of blue crab sensor populations. Upstream motion is induced by a binary response to supra-threshold spikes of concentration, and cross-stream steering is controlled by contrast between bilaterally-separated sensors. Like animal strategies, the developed control algorithm is dynamic. This property allows the algorithm to function effectively in the highly irregular turbulent environment and produces adaptive adjustments of motion to minimize the distance to the source of a plume. Tracking trials indicate that roughly 80% of the tracks successfully stop near the plume source location. Both success rate and movement patterns of the tracker compare favorably to that of blue crabs searching for odorant plume sources, thus suggesting that our sensory-mediated behavior hypothesis are generally accurate and that the associated tracking mechanisms may be successfully implemented in hardware.

Subsurface Plume Tracking Using Sparse Wireless Sensor Networks

Deployment of sensors for tracking chemical plumes such as those in the subsurface can be quite expensive. A compressed data gathering scheme for chemical plume tracking is presented. With only a fraction (about 25%) of the measurement points required to achieve a given spatial resolution this novel ap-plication of compressed sensing can track the plume within 7% accuracy compared to the case of a full sensor array. The scheme also gathers and re-distributes information of the sensors to the entire network, compress-ing with Discrete Wavelet Transform. The scheme can be used to disseminate global tracking information to sensors as well, with savings in communications by a factor of 5 in average, if such capability is required. The scheme is capable of interpolating randomly missing sensor points with significant accuracy. It also supports data fusion as a simple addition of coefficients requiring no changes to the message length.

Comparing Insect-Inspired Chemical Plume Tracking Algorithms Using a Mobile Robot

Four chemical plume-tracking algorithms have been compared using a mobile robot. These algorithms are based upon hypotheses proposed to explain the plume-tracking behavior of flying insects. They all use information from a wind sensor and a single chemical sensor to determine how the agent should move to locate the source of the chemical plume. The performance of the robot using each of the algorithms was tested in a wind tunnel under a range of wind speeds (0.55, 0.95, and 1.4 m/s) using a model chemical (ionized air). The robot was capable of tracking the ion plume to its source effectively with each algorithm, having an overall success rate of over 85%. The simplest implemented algorithm, surge anemotaxis, was found to be the fastest. However, the shape of the tracking paths observed indicated that this simple algorithm may not explain the plume-tracking behavior of certain insects as well as the other algorithms tested. Further tests are required to see if the surge anemotaxis algorithm remains the most efficient under more realistic wind conditions.

Effectiveness of Insect-Inspired Chemical Plume-Tracking Algorithms in a Shifting Wind Field

Tracking a plume of chemical back to its source is made difficult due to the complexity of plume structure caused by turbulence and shifts in the prevailing wind direction. Insects overcome this problem using forms of anemotaxis, which involve traveling upwind when an attractive chemical is perceived. In this study, two series of insect-inspired plume-tracking algorithms were implemented on a mobile robot and their performance compared under changing wind conditions in a wind tunnel. The robot was capable of sensing wind velocity and the level of a plume of ions. Ion sensors respond and recover far more rapidly than do conventional chemical sensors, so the substitution of an ion plume for a chemical plume allowed the algorithms to be implemented with rapid responses to changing plume concentration. The addition of a specific behavioral response to a wind shift decreased the time taken for the robot to find the plume source in the event of a wind shift. Increased speed came with only a minor drop in the success rate of the searching. Anemotaxis is an effective approach to chemical plume tracking with robots. The performance of these simple algorithms can be improved by modest increases in the complexity of the algorithms.

Chemical plume tracking. 3. Ascorbic acid: a biologically relevant marker.

Dynamic characteristics of the amperometric sensing system for tracking of turbulent chemical plumes have been studied. The correlation analysis requires that such sensors respond rapidly and have long-term stability and minimal or low-flow sensitivity. Moreover, for practical purposes, such sensors must respond to an electrochemical marker that would be found in or at least be compatible with the diet of marine animals. Ascorbic acid is such a compound and can be electrochemically oxidized. Its long-term dynamic behavior on several types of electrodes has been studied. It has been found that a Pt electrode coated with polyaniline satisfies all the above requirements. However, this system has a peculiar dynamic behavior that affects the results of the correlation analysis, namely, at the higher frequencies. The behavior of such system in the virtual plume setup has been characterized and its usability for detection of fluctuating concentration of ascorbic acid in saline solution has been confirmed.

A multidisciplinary study of spatial and temporal scales containing information in turbulent chemical plume tracking

This report describes the results of a multidisciplinary study of turbulent chemical plume tracking of blue crabs and autonomous agents. The study consists of a coordinated investigation of animal behavior, fluid mechanics, strategy simulations, and chemical sensing. The objective is to provide a comprehensive understanding of chemical plume tracking in a single biological system and to prescribe strategies that are effective for autonomous agents. The consensus of the study is that spatial variation in the plume, measured by sampling at multiple locations simultaneously, yields information that is useful for plume tracking. Behavioral investigations reveal that blue crabs demonstrate the ability to detect the chemical plume and use lateral movements to avoid losing contact with the odor. Blue crabs move rapidly towards the source, strongly suggesting that temporal comparisons of odor properties are not employed during navigation. Analysis of the concentration fields reveals that a spatial correlation between spanwise-separated sensors indicates the relative direction of the plume centerline over short time periods provided the sensor spacing is scaled appropriately relative to the plume. Similarly, simulations of tracking strategies reveal an optimal separation for the sensors at a distance roughly equal to the plume width; both smaller and larger sensor spans degrade tracking performance. The simulations further reveal an optimal sensor size above which the fine details of the concentration distribution are obscured and below which there is insufficient contact with the odor to enable effective navigation. Finally, analysis of the chemical signal shows that the frequency dependent correlation function between two (or more) sensors indicates the relative position of the source.

Chemical plume tracking. 1. Chemical information encoding.

It is shown experimentally that chemical information can be encoded and preserved in flowing liquid streams. It can be retrieved by chemical sensing arrays using correlation analysis. This finding is important for understanding of the mechanism of chemotaxis as practiced by some aquatic animals and also is a necessary prerequisite for construction of chemical plume tracking robots.

Chemical plume tracking. 2. Multiple-frequency modulation.

The purpose of this research is to estimate the effect of turbulent mixing on the information content in a chemically encoded signal, to investigate the effect of the presence of multiple encoded frequencies, and to evaluate the information contained in the higher harmonics of the coherence spectra. The virtual plume instrument is used to mimic the flow conditions and signal patterns in a real chemical plume. Two-frequency modulation experiments are performed using solenoid valves to introduce concentration plugs of a marker into the carrier flows at certain constant frequencies. In our experiments, the length of the delay elements and the dispersion were varied to mimic different characteristics of the turbulent plume. In addition, an artificial but uncorrelated white noise was added to the raw amperometric signals in order to simulate the "noisy" conditions existing in a real plume. Our experiments reveal that the introduced turbulence has only a marginal effect on the coherence spectra. Moreover, it is shown that when the second frequency is present in the plume, both fundamental frequencies can be unambiguously assigned. Higher harmonics in the coherence spectra have been found to depend on the distance from the source. These findings are important for understanding of the mechanism of chemotaxis and may also lead to the design of optimized search algorithms for chemical plume tracking robots.

Chemosensory guidance cues in a turbulent chemical odor plume

The characteristics of chemical odor plumes released into a turbulent open channel flow are evaluated in the context of chemical plume tracking. The objective is to assess the availability and usefulness of chemosensory cues to animals, such as benthic crustaceans, attempting to orient in the plume. Releasing fluorescent dye into the fully developed turbulent boundary layer of a large laboratory‐scale flume created turbulent odor plumes. Flow visualization of odor fields created with varying release velocity, release distance from the bed, and nozzle diameter indicated that chemosensory cues in plumes depend on the release characteristics as well as the ambient flow conditions. Thus, to understand animal behavior, it is important to quantify the plume release properties and characteristics. We chose to quantify concentration fields for the case of isokinetic release using the planar laser‐induced fluorescence technique. These measurements indicate that the time‐averaged concentration converges far too slowly to be useful to a foraging animal. Similarly, resolving the rise slope of a concentration burst requires sampling rates unattainable by animals, and the spatial variation of rise slope is too mild to follow without lengthy sampling periods. In addition, only mild variation with distance from the source is observed in the concentration burst magnitude and duration. Thus, the time‐averaged concentration, rise slope, and burst shape all appear to have limited usefulness for plume orientation for animals known to orient effectively to these types of odor sources.