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Purpose Using modeling approaches, this paper aims to propose different mathematical models for estimating the different components of the solar radiation as well as the received solar energy by a collector. Design/methodology/approach In this article, the authors consider three mathematical models to estimate the solar radiation captured at ground level by a solar collector. These models are Capderou model, Liu & Jordan model and R.sun model. In the context of the design of experiments, we performed measurements of solar radiation received by a collector using a pyranometer. The obtained measurements were compared with the three mathematical models. Findings The comparison enabled the subsequent evaluation to determine the most appropriate model that best fit for our region. As a result, the Capderou model reveals to be the most suitable for our region. Originality/value Estimation of solar radiation at ground level (received by a collector) is of paramount importance for the design and optimization of solar energy systems. Nevertheless, many factors influence the amount of energy received by a collector situated at a ground, such as the longitude of the location, latitude, altitude, tilt collector orientation, temperature and humidity of the environment, wind speed, etc. Because of the complex influence of these parameters, the received solar radiation by the collector is a dynamical and a random process.

This paper presents the use of a Multi-Layer Perceptron Neural Nets (MLP-NN) for voice recognition dedicated to generating robot commands. Our main goal concerns the estimation of the minimal number of elements required for the learning process in order to ensure an acceptable success of the neural nets recognition. As the MLP requires references for the spoken words, we have provided these references by means of a supervised classifier based on the mean square error. An experimental approach has been followed for the design of experiments enabling to determine the minimal elements in the sample for each voice command. Satisfactory results have been obtained leading to a better understanding of variability of the system functioning. Finally, we have noticed that the success rate of the MLP and the minimal number of elements used for the learning process depend on the spoken word structure and of the variability of the actual work situation (word length, noise, speaker, etc).

This paper initially presents the results of the analysis of a non linear on/off control system which is capable of generating a pulse width modulation (PWM). This technique can be used to design PWM choppers that can be dedicated to regulate fluctuating power supplies (photovoltaic, wind turbines, etc.). However, since the PWM losses mainly depend on the switching frequency, thus, the determination of an optimal frequency is required. Indeed, on the one hand, we seek to operate at high frequencies to reduce the residual noise by filtering. On the other hand, there is a limitation of the switching frequency due to the physical switching elements properties. Therefore, a compromise has to be made in order to determine an optimal switching frequency that minimizes the switching power losses. The main objective of this work is to present a technique that enables to sizing the chopper parameters based on the minimizing of the switching losses. An illustrative example of the proposed technique for sizing a PWM chopper is presented.

Cable-based robots as well as their control are relatively new fields of research. The objective of this work is to design, simulate and compare two robot control techniques which are dedicated to be implemented for cable-based robots. The first controller is a classical proportional derivative one (PDC) while the second controller is the sliding mode one (SMC).The proposed controllers are inserted into a closed loop around the cable-based robot for ensuring point to point transfer operations and trajectory tracking. Simulations have been carried out confirming the effectiveness of the PDC and SMC for controlling planar cable-based robots. Performances concerning settling time, precision, vibration and system stability are analyzed and compared. Some simulation results are presented showing, for each control techniques during trajectory tracking, the instantaneous profile evolution of cable lengths and cable tensions.

This paper presents the design and the implementation of a multimodal operator interface dedicated for planar cable-based robots. Three interactive robot control modes which have been implemented are namely point and click based control, gesture-based control and voice based control. Point and click based control enables robot control by simply clicking on features appearing on images of the robot workspace. Gestural-based control enables robot control by means of human operator gestures. Voice based control enables robot control by means of natural speech. Successful experiments have been tested on a homemade planar cable-driven robot. The availability and the combination of these three modes improve greatly the capability of the global system.