Wilmar Hernandez

Improving the response of a wheel speed sensor using an adaptive line enhancer

In this paper, an Adaptive Line Enhancer (ALE) based on a Frequency-Domain Least-Mean-Square (FDLMS) adaptive algorithm is used to predict the response of a wheel speed sensor embedded in a car undergoing performance tests. In this case, an ALE is used to predict a signal buried in a broad-band noise background where we have little or no prior knowledge of the signal or noise characteristics. The results of the experiment show that this device behaves as an adaptive notch filter whose null points are determined by the frequency of the noise and/or interference corrupting the electrical signal, and these also show a significant improvement in the signal-to-noise ratio at the system output.

3D laser scanning vision system for autonomous robot navigation

The presented Technical Vision System realizes the principle of dynamic triangulation. This technique is able to resolve in real time a triple task: to detect a presence of significant obstacle in a robots neighborhood; locate its position in a robots field-of-view; obtain in a short time a digital map of the obstacle visible surface with metrological accuracy of coordinates and adjustable step of discretization. Some aspects of theoretical backgrounds, technical design, optical principle, mathematical framework, signal processing, prototype design and experimentation are presented in this paper.

Resolution improvement of dynamic triangulation method for 3D vision system in robot navigation task

This paper presents a technical vision system designed to resolve multiple tasks which are fundamental for autonomous navigation. These tasks include detecting the presence of a significant obstacle for a mobile robot, locate its position in the mobile robots field of view and create a digital map of the obstacles visible surface with metrological accuracy. This technical vision system has been introduced and explained in other publications; therefore this paper focuses mostly on signal conditioning, processing and resolution increase for mobile robot navigation.

Remote Sensor for Spatial Measurements by Using Optical Scanning

In this paper, we propose a low-cost contact-free measurement system for both 3-D data acquisition and fast surface parameter registration by digitized points. Despite the fact that during the last decade several approaches for both contact-free measurement techniques aimed at carrying out object surface recognition and 3-D object recognition have been proposed, they often still require complex and expensive equipment. Therefore, alternative low cost solutions are in great demand. Here, two low-cost solutions to the above-mentioned problem are presented. These are two examples of practical applications of the novel passive optical scanning system presented in this paper.

Automotive FDS Resolution Improvement by Using the Principle of Rational Approximation

In this paper, a novel method of frequency counting of signals coming from automotive sensors is presented. The present method helps to improve fast resolution of output parameters of typical automotive frequency-domain sensors (FDS). Controlling the electromechanical systems in todays cars is a task that requires a high processing speed. The method proposed here has been tested under computer experiments, and theoretical results have shown that it meets the requirements of speed of response and offset error of the parameters under measurement. Here, both a principle of rational approximation and its application to fast registration of frequency changes in the signal that is proportional to the physical parameter under measurement are shown. Finally, some experimental results are shown as well.

Improving the Response of Accelerometers for Automotive Applications by Using LMS Adaptive Filters

In this paper, the least-mean-squares (LMS) algorithm was used to eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications. This kind of accelerometer is designed to be easily mounted in hard to reach places on vehicles under test, and they usually feature ranges from 50 to 2,000 g (where is the gravitational acceleration, 9.81 m/s2) and frequency responses to 3,000 Hz or higher, with DC response, durable cables, reliable performance and relatively low cost. However, here we show that the response of the sensor under test had a lot of noise and we carried out the signal processing stage by using both conventional and optimal adaptive filtering. Usually, designers have to build their specific analog and digital signal processing circuits, and this fact increases considerably the cost of the entire sensor system and the results are not always satisfactory, because the relevant signal is sometimes buried in a broad-band noise background where the unwanted information and the relevant signal sometimes share a very similar frequency band. Thus, in order to deal with this problem, here we used the LMS adaptive filtering algorithm and compare it with others based on the kind of filters that are typically used for automotive applications. The experimental results are satisfactory.

A simple ‘bandgap’-type magnetoamplifier

Abstract A simple and very sensitive amplifier circuit for the signal amplification of a lateral magnetotransistor is presented. This circuit was originally used as a bandgap voltage reference source, so its attainable temperature stability is good. Both collectors of the lateral magnetotransistor are forced to be practically equipotential. A sensitivity of 13.30 T −1 with a thermal drift of 30 mV in 40 K (due to the sensor) around room temperature has been obtained experimentally.

Frequency domain automotive sensors: Resolution improvement by novel principle of rational approximation

It is described a different way to make a frequency counting process that helps to improve fast resolution of an output parameter of a typical automotive frequency domain sensor. After a brief explanation about FDS, specifically SAW sensors work, it is explained a Principle of rational approximation and it is shown its application for fast registration of frequency changes on the adjustable reference oscillator. Some experimental testing is introduced.

Improving the response of wheel speed sensors by using robust and optimal signal processing techniques

In this paper, robust and optimal adaptive filtering is used to cancel noise and interference in wheel speed sensors. Noise and interference corrupt the information coming from the sensors, and it is very difficult to diminish their negative influence on the signal of interest by using the classical approach to filtering. In this case the relevant signal is buried in a broad-band noise background where we have little or no prior knowledge of the signal or noise characteristics. The results of the experiments show that the signal of interest and the noise (all forms of interference, deterministic as well as stochastic) share the same frequency band and that the filter used significantly reduced the noise corrupting the information from the sensor while left the true signal unchanged from a practical point of view.

Precise optical scanning for multiuse

Many approaches for remote measurement techniques for object surfaces and approaches for 3D object recognition have been proposed; but often they still require complex and expensive equipment. Not least due to the rapidly increasing number of efficient 3d hard- and software system components, alternative low cost solutions are in great demand. We propose such a low-cost system for 3d data acquisition and fast surface registration by digitized points Cartesian coordinates matrix keeping. There are presented experimental research and computer simulation of various natural factors which can affects the normal functioning of the passive optical scanning aperture under proposition.