The complete coverage path planning is a process of finding a path which ensures that a mobile robot completely covers the entire environment while following the planned path. In this paper, we ...propose a complete coverage path planning algorithm that generates smooth complete coverage paths based on clothoids that allow a nonholonomic mobile robot to move in optimal time while following the path. This algorithm greatly reduces coverage time, the path length, and overlap area, and increases the coverage rate compared to the state-of-the-art complete coverage algorithms, which is verified by simulation. Furthermore, the proposed algorithm is suitable for real-time operation due to its computational simplicity and allows path replanning in case the robot encounters unknown obstacles. The efficiency of the proposed algorithm is validated by experimental results on the Pioneer 3DX mobile robot.
This paper is concerned with the problem of finding a time-optimal velocity profile along the predefined path for static formations of mobile robots in order to traverse the path in shortest time and ...to satisfy, for each mobile robot in the formation, velocity, acceleration, tip over and wheel slip prevention constraints. Time-optimal velocity planning is achieved using so called bang-bang control where minimum and maximum accelerations of the formation are alternating. The developed trajectory planning algorithm is demonstrated on the formation of differential drive mobile robots.
This paper presents a new global vision system for tracking of multiple mobile robots. To the best knowledge of the authors it outperforms all existing global vision systems with respect to ...measurement precision and accuracy, high speed and real time operation and reliable tracking of large (theoretically unlimited) number of robots under light intensity changes. The originality of the proposed system lies mainly in specially designed robot marks and robots’ poses measuring directly in Bayer format image delivered by the camera. These two measures enable robust pose estimation of the robots with subpixel precision, while the significant simplification of the image processing algorithms ensures tracking of many robots with very high framerates. With algorithms running on a 3 GHz Athlon 64 processor 65 robots can be tracked at 80 fps. Moreover, in order to perform a thorough analysis of the system performances related to defined requirements, we propose a new experimental procedure that can serve as a benchmark for evaluation of other systems for the same purpose.
This paper presents an experimental overview of common trajectory tracking methods for nonholonomic mobile robots: linear control, nonlinear control and model predictive control. All methods are ...compared experimentally on a two-wheel mobile robot with differential drive. The goal was to determine which control method is the best with respect to robustness and low trajectory tracking error. Thereby, a special emphasis is given on a fast real-time trajectory tracking and behavior in conditions near robot velocity and acceleration limits.
We present a method for real-time computation of clothoid coordinates that guarantees bounded approximation error over a wide range of clothoid parameters provided that the clothoid's orientation ...change and length areReal-time approximation bounded. It is shown that coordinates of clothoid with any parameters can be computed from those of a single clothoid (with fixed parameters), using appropriate geometrical transformations. A comprehensive analysis is given on how to determine a required set of clothoids and, based on this, how to sample a clothoid in a lookup table in order to achieve required approximation precision. The algorithm is computationally very efficient and therefore suitable for real-time path planning, as well as for other applications that benefit from fast clothoid computation.
This paper presents a new global vision system for tracking of multiple mobile robots, with special emphasis on following requirements: (i) high measurement precision and accuracy, (ii) robustness to ...light intensity changes, (iii) ability to track unlimited number of robots, and (iv) high speed and real time operation. In order to fulfill these requirements we use an IEEE 1394 camera with 80 fps, which delivers images in so called Bayer format. We also design a specific robot mark that enables measurement of robot locations directly in Bayer format image with subpixel precision. The developed vision system fulfils all of given requirements, which was verified by carefully performed experiments.
This paper is concerned with the problem of finding an optimal velocity profile along the predefined path in order to traverse the path in shortest time. A dynamic model of the mobile robot that ...accounts for robot actuator constraints is derived. It is shown how to use this dynamic model to express acceleration limits and velocity limit curve required by the optimal time-scaling algorithm. The developed trajectory planning algorithm is demonstrated on the Pioneer 3DX mobile robot. A method is very flexible and can be extended to account for other constraints, such as limited grip between the robot wheels and the ground.
This paper presents a new online path-smoothing algorithm for smoothing a path that consists of straight line segments and is primarily intended for differential drive mobile robots. Algorithm allows ...non-zero initial path curvature, which is important for replanning. Further, algorithm uses clothoid curves as primitives for path smoothing, which have inherent property that their curvature changes proportionally with distance traveled along the curve.
Za uspješnu primjenu mobilnih robota u radnim prostorima s ljudima potrebno je riješiti različite probleme navigacije. Jedan od problema navigacije jest kreiranje modela i uključivanje novih ...informacija o radnoj okolini mobilnog robota u model radne okoline ili kartu. Članak opisuje često korištene tipove mrežastih karata prostora zasnovanih na očitanjima ultrazvučnih osjetila udaljenosti. Obrađeni modeli prostora su: (i) Bayesova karta, (ii) Dempster-Shaferova karta, (iii) neizrazita karta, (iv) Borensteinova karta, (v) MURIEL karta i (vi) TBF karta. Osim opisa, u članku je dana i usporedba implementiranih algoritama prema memorijskim i računskim zahtjevima. Simulacijska provjera napravljena je korištenjem AMORsim simulatora mobilnog robota za programski paket Matlab, a eksperimentalna provjera napravljena je korištenjem Pioneer 3DX mobilnog robota. Također su prikazani dobiveni rezultati uz usporedbu njihove kakvoće.
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