robot
A gas sensitive robot as the described above is of only use for carrying out specific olfaction-related tasks exclusively (see Section 2.4). That is, even if the main charac- teristic of a gas sensitive robot is to be able to detect and analyze volatile substances, it is desired for such a robot to be able to interact with the environment based on the sensed information. Additionally, for high level olfaction applications it is almost necessary to attend to other sensing disciplines rather than only olfaction, thus, the collaboration between sensing modalities should be allowed by the robot.
With this goal, the structure and components of Rhodon were once more cus- tomized. The main modification was the incorporation of a robotic arm, a research edition of the commercial JACO arm from Kinova [125]. This robotic arm is ideal to be used on a mobile robot, meeting the constraints of being lightweight and having a low power consumption. To increase the area of operation without interfering with other parts of the robot, the arm was placed at the top-center of the structure. To pro- vide weight-compensation when the arm is fully extended and prevent the swaying of the robot, a new set of batteries were placed at its rear. Figure A.4 depicts the location of the different components onboard Rhodon.
A metal bar was then attached to the structure of the robot to allow vision cam- eras to obtain images from a wider perspective. A Kinect sensor and a thermal camera
A.3. THIRD STAGE: MULTI-PURPOSE GAS SENSITIVE ROBOT 127
(a) (b)
Figure A.5: Images of Rhodon at its current stage. (a) Picture of an experiment where Rhodon was commanded to prepare a cocktail. (b) Detail of the attached e-nose aspiration to the robotic hand, and grasping of the plastic cup after the cocktail has been prepared.
were then positioned over the robotic arm, allowing the use of vision and range sens- ing for manipulating objets among other robotic tasks. Figure A.5 shows different pic- tures of Rhodon from an experiment where it was commanded to prepare a cocktail. In this experiment, almost all the capabilities of Rhodon were tested, ranging from lo- calization and path planning, to olfaction and object manipulation. A video describing this experiment can be found at the Youtube channel of the MAPIR group at http: //mapir.isa.uma.es/ or directly at Youtube: http://youtu.be/BsQMewX8yNQ
Appendix B
An olfaction plugin for
simulating mobile robotics
olfaction
A noticeable characteristic of most mobile robotics olfaction experiments is their complex and time consuming development life-cycle. The main reason behind it lies in the impossibility of deriving a ground truth (GT) representation of the gas dis- tribution in the environment, making difficult, almost impossible, to validate new algorithms or to compare different proposals aiming at the same objective. For this reason, real experiments usually employ complex setups with the intention of con- trolling, as much as possible, the dispersion of volatiles (generation of plumes with fans, shutting doors and windows to reduce undesired airflows, etc.), but even then, the results cannot be completely validated because of the lack of information about the real state of the gas distribution.
As in many other scientific fields, this drawback can be considerably reduced by making use of simulation environments. Among their many advantages, we can highlight:
• They provide a ground truth of the simulated environment, a fundamental req- uisite for validating new algorithms.
• Repeatability is easily achieved and so the comparison of different algorithms. • Simulation allows testing an algorithm under different and complex environ- mental conditions (e.g. laminar flow, turbulent flow, plumes, etc.), and can be even more realistic than traditional experiments, as they allow the free config- uration of the environmental parameters found in the operational application. • Using simulated data is generally cheaper, safer (e.g. toxic gases) and less time-
consuming than conducting laboratory experiments.
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APPENDIX B. AN OLFACTION PLUGIN FOR SIMULATING MOBILE ROBOTICS OLFACTION
However, due to the still low presence of artificial olfaction in the area of mobile robotics, most currently-existing robotic simulators do not account yet for olfaction methods and models. In this appendix, an olfaction plugin developed to provide the necessary mechanisms for efficiently testing and validating algorithms related, but not limited to, gas distribution mapping (GDM), is introduced. This plugin, used in some of the olfaction experiments presented in this thesis, is designed to work with the robotic simulator included into the Open Mobile Robotics Architecture (Open- MORA) [52].
The organization of this appendix is as follows: after a review of the most spread mobile robotics simulators, an overview of the chosen OpenMORA’s simulation envi- ronment is provided in Section B.2. Then, the proposed olfaction plugin is introduced in Section B.3, to finish with an illustrative example in Section B.4.
B.1
Related research
In robotics research, simulation plays a significant role as a tool for quickly and ef- ficiently testing new concepts, strategies, and algorithms. Its importance can be ap- preciated in the number of simulation toolkits that have been proposed, including: Webots [105] a commercial development environment used to model, program and simulate mobile robots, with a large choice of simulated sensors and actuators, the Virtual robot experimentation platform (v-rep) [35], a distributed and modular robotic framework that concurrently simulates control, actuation, sensing and monitoring, or CARMEN [17] an open-source collection of software for mobile robot control from the university of Carnegie Mellon, which implements a moderately useful 2-D robotic simulator.
When simulating multiple mobile robots, Stage [46] is possibly the most com- monly used 2D swarm robot simulator for research and university teaching nowadays, while Gazebo [75] extends the framework to 3D dynamic multi-robot environment, providing tools for recreating complex world scenarios.
Related to robotics olfaction, Cabrita et al. [16] proposed a Player/Stage based simulator for mobile robot olfactory experiments, focusing mainly on extending its functionality to support chemical plume simulation and plume tracking. This frame- work lacks, nevertheless, of a realistic model for the gas sensors and the inclusion of gas distribution mapping algorithms. In [93], the simulation of a single robot in a dynamic time-variable environment generated with the computational fluid dy- namics software Fluent [4] is proposed to study the gradient and equilateral trian- gle search methods. However, this software package only considers a simple mobile object equipped with a gas sensor, thus it does not provide the variety of tools nec- essary to simulate a mobile robot (collision avoidance, path planning, etc.). Finally, a more complete olfaction simulator for mobile robotics is presented as a plugin for Webots [105]. Although it includes the simulation of odor dispersion based on the filament-based atmospheric dispersion model proposed by Farrell et al. [28], it still lacks a model of the gas sensors and the implementation of gas mapping methods.