Mobile Robot Path Planners with Memory for Mobility Diversity Algorithms

Mobile robots (MRs) using wireless communications often experience small-scale fading so that the wireless channel gain can be low. If the channel gain is poor (due to fading), the robot can move (a small distance) to another location to improve the channel gain and so compensate for fading. Techniques using this principle are called mobility diversity algorithms (MDAs). MDAs intelligently explore a number of points to find a location with high channel gain while using little mechanical energy during the exploration. Until now, the location of these points has been predetermined. In this paper, we show how we can adapt their positions by using channel predictors. Our results show that MDAs, which adapt the location of those points, can in fact outperform (in terms of the channel gain obtained and mechanical energy used) the MDAs that use predetermined locations for those points. These results will significantly improve the performance of the MDAs and consequently allow MRs to mitigate poor wireless channel conditions in an energy-efficient manner

Robotic Mobility Diversity Algorithm with Continuous Search Space

Small scale fading makes the wireless channel gain vary significantly over small distances and in the context of classical communication systems it can be detrimental to performance. But in the context of mobile robot (MR) wireless communications, we can take advantage of the fading using a mobility diversity algorithm (MDA) to deliberately locate the MR at a point where the channel gain is high. There are two classes of MDAs. In the first class, the MR explores various points, stops at each one to collect channel measurements and then locates the best position to establish communications. In the second class the MR moves, without stopping, along a continuous path while collecting channel measurements and then stops at the end of the path. It determines the best point to establish communications. Until now, the shape of the continuous path for such MDAs has been arbitrarily selected and currently there is no method to optimize it. In this paper, we propose a method to optimize such a path. Simulation results show that such optimized paths provide the MDAs with an increased performance, enabling them to experience higher channel gains while using less mechanical energy for the MR motion

Robust Trajectory Planning for Robotic Communications under Fading Channels

We consider a new problem of robust trajectory planning for robots that have a physical destination and a communication constraint. Specifically, the robot or automatic vehicle must move from a given starting point to a target point while uploading/downloading a given amount of data within a given time, while accounting for the energy cost and the time taken to download. However, this trajectory is assumed to be planned in advance (e.g., because online computation cannot be performed). Due to wireless channel fluctuations, it is essential for the planned trajectory to be robust to packet losses and meet the communication target with a sufficiently high probability. This optimization problem contrasts with the classical mobile communications paradigm in which communication aspects are assumed to be independent from the motion aspects. This setup is formalized here and leads us to determining non-trivial trajectories for the mobile, which are highlighted in the numerical result

Robust Trajectory Planning for Robotic Communications under Fading Channels

We consider a new problem of robust trajectory planning for robots that have a physical destination and a communication constraint. Specifically, the robot or automatic vehicle must move from a given starting point to a target point while uploading/downloading a given amount of data within a given time, while accounting for the energy cost and the time taken to download. However, this trajectory is assumed to be planned in advance (e.g., because online computation cannot be performed). Due to wireless channel fluctuations, it is essential for the planned trajectory to be robust to packet losses and meet the communication target with a sufficiently high probability. This optimization problem contrasts with the classical mobile communications paradigm in which communication aspects are assumed to be independent from the motion aspects. This setup is formalized here and leads us to determining non-trivial trajectories for the mobile, which are highlighted in the numerical result

Optimal trajectory design for a DTOA based multi-robot angle of arrival estimation system for rescue operations

In this article we present an angle of arrival (AoA) multi-robot system for rescue purposes which takes advantage of robots' mobility to improve the position estimate of an unknown target. The robots move according to a certain trajectory (a sequence of stopping points) designed to minimize the variance of the AoA estimation. We present two different techniques to generate these optimal trajectories, with each technique having its own advantage

Mobility Diversity-Assisted Wireless Communication for Mobile Robots

Mobile robots, that wish to communicate wirelessly, often suffer from fading channels. They need to devise an energy efficient strategy to search for a high channel gain position in a near vicinity from which to begin communications. Such a strategy has recently been introduced through the Mobility Diversity with Multi-Threshold Algorithm (MDMTA). In this paper, we establish the theoretical framework for a generalized version of the MDMTA. This allows improved wireless communications in fading channels for mobile robots via intelligent robotic motion with low mechanical energy expenditure

Clonal effect on rooting and acclimation rates for in-vitro micropropagation in hybrid walnut (Juglans x intermedia Mj 209): preliminary observations

The success of walnut (Juglans sp.) planted forests for timber production have been very variable and genetic material is considered as one of the main drivers (together with site selection and forest management) for the success or failure of the plantations, as the performance of the trees from seed material is very variable. Considering the relevance of this genetic material, several clones have been selected and research have been conducted in order to improve micropropagation procedures. The objective of the present study is to analyze the effects of different clones in the rooting and acclimation rates for in-vitro micropropagation in hybrid walnut (Juglans x intermedia Mj 209). The results show a significative effect of clones on the rooting and the total micropropagation efficiency rates, but not on the acclimation rate. The efficiency rate of D-117 (65%) is considered statistically higher than the one for D-15 (38%), caused by a higher rooting rate of D-117 (73%) compared with D-15 (55%), because acclimation rate (57%) did not show any clone effect. Considering these differences in the micropropagation success, it might be considered (together with other factors) for clone selection to increase the general performance of the plant production units in large-scale propagation