Mechanical industry is facing major challenges in the 21st century. Products with high quality material, more complex geometry is challenging productivity and cost efficiency, which represents profit in today's ec...
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Next-generation robotics is based on transformation of the industrial robots to something that everyone can accept, teach and utilize. This utilization will be independent of the purpose (manufacturing, relaxation, nu...
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Path planning among obstacles for nonholonomic systems is a widely researched area nowadays, but it is still one of the most challenging problems in autonomous navigation. We have recently presented a rapidly explorin...
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Path planning among obstacles for nonholonomic systems is a widely researched area nowadays, but it is still one of the most challenging problems in autonomous navigation. We have recently presented a rapidly exploring random tree based global planner (RTR) and a steering method (C*CS) for car-like vehicles, which uses circular and straight movements. With the aid of these two methods it is possible to obtain a feasible path, even in narrow spaces and in situations requiring non-trivial maneuvers. This paper presents an improved solution for environments, where not all obstacles are known at the beginning and these are discovered during the motion of the robot. We also introduce an extension to the presented algorithm to achieve paths of better quality, i.e. more similar to a reasonable path generated by a human driver.
The need for intelligent autonomous vehicles is increasing in industrial and everyday life as well. Path planning among obstacles is one of the challenging problems to be solved to achieve autonomous navigation. In th...
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The need for intelligent autonomous vehicles is increasing in industrial and everyday life as well. Path planning among obstacles is one of the challenging problems to be solved to achieve autonomous navigation. In this paper we present a global geometric path planning method for car-like robots, which proved to be effective especially in cluttered environments, containing narrow passages. Navigation in such scenarios usually requires non-obvious manoeuvring with many reversals, which is challenging even for a human driver. We also present a comparative analysis of our method with possible alternatives from the literature to illustrate its effectiveness regarding computation time and path quality.
This paper presents a comprehensive solution for path planning and control of two popular types of autonomous wheeled vehicles. Differentially driven and car-like motion systems are the most widespread structures amon...
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This paper presents a comprehensive solution for path planning and control of two popular types of autonomous wheeled vehicles. Differentially driven and car-like motion systems are the most widespread structures among wheeled mobile robots. The planning algorithm employs a rapidly exploring random tree based global planner (RTR), which generates paths made of straight motion and in place turning primitives. Such paths can be directly followed by a differential drive robot. Carlike robots have a minimum turning radius constraint, hence we present a local steering method (C*CS) which obtains a path consisting circular and straight movements based on the primary RTR-path, without losing the existence of the solution. Additionally, a velocity profile generation algorithm is presented, which is responsible for the distribution of the time parameter along the geometric path, taking the physical limitations of the robot into account. Finally, control algorithms for path following are given for both robot types. Simulations and real experiments show the effectiveness of these methods, even is constrained environments containing narrow corridors and passages.
The execution of construction projects such as a highway construction or the elevation of a new bridge is a complex, highly equipment-intensive process and are subject to many different uncertainties. This is very sim...
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The execution of construction projects such as a highway construction or the elevation of a new bridge is a complex, highly equipment-intensive process and are subject to many different uncertainties. This is very similar to the manufacturing execution level in production systems where predefined productions plans and schedules cannot be completely implemented due to unexpected internal and external changes and disturbances. Following this analogy, the paper proposes the application of a discrete-event simulation based method which was already applied in the decision-support for manufacturing control to develop the decision-support in the execution of a construction project where the effects of the deviation from the short-term schedule can be easily and quickly analyzed.
Evaluating mobile and desktop applications from usability aspects is becoming trending as the usage of electronic devices increases every day. Both user loyalty and usage efficiency are key factors in developing succe...
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ISBN:
(纸本)9781467381307
Evaluating mobile and desktop applications from usability aspects is becoming trending as the usage of electronic devices increases every day. Both user loyalty and usage efficiency are key factors in developing successful applications, given the wide variety of the market. An affordable and portable monitoring environment for desktop and mobile platforms could fulfill the specific needs of user experience researchers. In this paper we present a system that monitors the physiological signals of the user while using any application installed on the devices. As a result, we are able track the eye movement, ECG and EEG signals, and analyze the combined data provided by these sensors. Results are visualized in a way that user experience experts can follow effortlessly application usage and cognitive processes of the user, which makes it possible to improve even further the user interface to boost productivity and user loyalty, and lower frustration.
Children with learning disabilities require the supervision of special expert teachers during their learning process. The recent years, educational pieces of software for students with dyslexia, dysgraphia, dyscalculi...
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ISBN:
(纸本)9781467381307
Children with learning disabilities require the supervision of special expert teachers during their learning process. The recent years, educational pieces of software for students with dyslexia, dysgraphia, dyscalculia or Attention Deficit Hyperactivity Disorder (ADHD) were developed. The problem of using such applications is twofold. First, there is no solution for distance supervising those students who have no direct access to the appropriate experts. Second, in classroom situations or frontal education, the attention of the supervisor is shared. In this paper we present a framework that gives universal solution to supervising students learning with mobile applications. In addition, biofeedback technologies are applied to represent the mental state of the children for the teacher, enabling her to infer their mood to keep the learning process on an optimal track.
The 60° flat-top modulation technique (also called two phase or discontinuous modulation) is a widely used method in the industry to reduce switching losses in three phase PWM inverters. This technique reduces th...
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The 60° flat-top modulation technique (also called two phase or discontinuous modulation) is a widely used method in the industry to reduce switching losses in three phase PWM inverters. This technique reduces the number of switchings via adding a zero sequence component to the output voltage. The added component is chosen such that one of the phase legs is not switched, but the phase-to-phase voltage still remains sinusoidal. In this article it is shown that 60° flat-top modulation can cause low order harmonic distortion. The cause and the magnitude of this effect is investigated, and an empirical method is given to decrease the distortion, which uses a modified version of the 60° flat-top modulator. The new method significantly decreases the current THD, at the cost of a minor increase in converter losses.
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