Evaluations of different technologies and solutions for indoor localization exist but only a few are aimed at the industrial context. In this paper, we compare and analyze two prominent solutions based on Ultra Wide Band Radio (Pozyx) and Ultrasound (GoT), both installed in an industrial manufacturing laboratory. The comparison comprises a static and a dynamic case. The static case evaluates average localization errors over 90 s intervals for 100 ground-truth points at three different heights, corresponding to different relevant objects in an industrial environment: mobile robots, pallets, forklifts and worker helmets. The average error obtained across the laboratory is similar for both systems and is between 0.3 m and 0.6 m, with higher errors for low altitudes. The dynamic case is performed with a mobile robot travelling with an average speed of 0.5 m/s at a height of 0.3 m. In this case, low frequency error components are filtered out to focus the comparison on dynamic errors. Average dynamic errors are within 0.3–0.4 m for Pozyx and within 0.1–0.2 m for GoT. Results show an acceptable accuracy required for tracking people or objects and could serve as a guideline for the least achievable accuracy when applied for mobile robotics in conjunction with other elements of a robotic navigation stack.
Unmanned aircrafts (UA) usually fly below 500 ft to be segregated from manned aircraft. However, while general aviation (GA) usually do fly above 500 ft in areas where UA are allowed to operate, GA will at times also fly below 500 ft. Consequently, there is a distinct risk of near‐miss encounters as well as actual midair collisions (MACs). This work presents a model for determining this risk based on physical parameters of the aircraft and actual figures for the numbers of GA in a given airspace, as well as the probability of having GA below 500 ft. The aim is to achieve a prediction with a precision better than one order of magnitude relative to the true MAC rate value. The model is applied to Danish airspace and the MAC rate for unmitigated operations of UA is found to be approximately 10−6 MAC per flight hour. The model is particularly well suited for beyond visual line‐of‐sight operations, and is useful for UA operators for conducting risk assessment of planned operations as well as for regulators for determining appropriate operational requirements.
21 January 2013 in IEEE Transactions on Automatic Control
This technical note examines the stochastic stability of noisy dynamics in discrete and continuous time. The notion of moment stability in the wide sense (MSWS) is presented as a generalization of ϵ-moment stability. MSWS is intentionally not based on stochastic convergence properties, since in most practically appearing systems convergence to any equilibrium is not present. A sufficient criterion for both MSWS and ergodicity is presented for a class of systems comprising a finite set of noisy dynamical systems among which switching is governed by a Markov chain. Stability/instability properties for each separate subsystem are assumed to be quantified by a Lyapunov function candidate together with an associated growth rate equation. For the set of Lyapunov functions, a compatibility criterion is assumed to be fulfilled, bounding the ratio between pairs of Lyapunov functions.
1 September 1997 in IEEE Transactions on Neural Networks
Neural networks for estimating conditional distributions and their associated quantiles are investigated in this paper. A basic network structure is developed on the basis of kernel estimation theory, and consistency is proved from a mild set of assumptions. A number of applications within statistics, decision theory, and signal processing are suggested, and a numerical example illustrating the capabilities of the elaborated network is given.
We propose a new concept, potentially distributable energy, in the field of autonomous mobile robots. Considering a system of multiple robots powered by batteries, each robot no longer works since its energy capacity is expired. To extend operating time, the robot needs to replenish energy through recharging energy. To date, except research on vaccum cleaning robots that are able to recharge battery when docking with the fixed station has been achieved, there does not exist any research of energy distribution to prolong operating time in a large population of mobile robots. This could be caused by the lack of using rechargeable battery in the fact that the robot has to normally spend the charging-time much longer than the operating time. This paper presents simulation results of mobile robots that are capable of not only self-recharging energy but also exchanging batteries to the other robots. Initially, we describe a simulation of multiple mobile robots, and then issue rules of battery exchange, which is formulated under constraints of workload, distance and remaining capacity. The simulation shows that: (a) a robot is able to be energetically autonomous if its energy can be replenished by the other robots or it is able to come back to the main charging station to replenish itself; (b) energy of a robot is always under constraints of energy distribution of the mother charging station and the other robots; (c) distributed energy balance is the main elements to decide a number of robots in a specific area and an ideal location of the repository when one wants to deploy a large population of autonomous mobile robots. Finally, based on results of the simulation we adjust rules for our real multirobot system.