Tool condition monitoring systems are essential in micromilling applications. A tool's slenderness requires high-precision monitoring systems for online measurements. In most cases, tool health is indirectly estimated by processing and analyzing the cutting process parameters. In that sense, the main challenge lies in the proper selection of the process parameters and their processing techniques, so that a robust and accurate assessment of the tool's health is obtained. This paper proposes a frequencyand time-frequency-based analysis of cutting force and vibration signals for estimating the tool condition of a high-speed micromilling process. Measurements obtained from different cutting conditions were utilized in the analysis. The results indicate variations in the dominant frequencies, which result from tool wear. Furthermore, it is important to note that the analysis results obtained from the two process signals provide more reliable results and improve the sensing bandwidth.

This paper presents a robot prototype for an undergraduate laboratory program designed to fulfill the criteria laid out by ABET. The main objective of the program is for students to learn some basic concepts of embedded systems and robotics, and apply them in practice. For that purpose, various practical laboratory exercises were prepared to teach different aspects of communications, control, mechatronics, and microcontrollers. The practicals are organized such that the students can systematically solve real-world problems. The most important feature of the presented program is that, it incorporates interdisciplinary knowledge, and inculcates technical and professional skills required in pursuing a successful career. Furthermore, students and instructors can modify the software and hardware units of the robot prototype as necessary, to explore more ideas and to apply the robot in other mechatronics-related courses. A digital electronics course taught at the Automation Department at Universidad Autónoma de Querétaro, Querétaro, Mexico, is presented as a case study in which the evaluation process was based on ABET criteria and the corresponding student outcomes. A student survey elicited students' observations of, and interest in, the learning process. The positive student feedback and student academic outcomes indicate that the inclusion of prototype had a significant impact on student academic outcomes.

This article proposes a tracking controller for servomechanisms with a continuous friction model. The parameters of this model are estimated through a proposed two-step offline identification methodology that uses a linear extended state observer (LESO) based on the integral of position measurements, termed as ILESO. In the first step, the viscous and Coulomb coefficients of this friction model are estimated by the ordinary least squares method. The second step employs these estimates to obtain the initial guess for the nonlinear least squares method that identifies all the parameters of the nonlinearly parameterized friction model. Finally, a backstepping controller is designed for reference tracking, which uses the estimated offline friction model and online estimations of the servo position, velocity, and system uncertainty. These online estimations are provided by a modified ILESO, termed as FILESO, that has a similar structure to that of the ILESO but incorporates the identified offline friction model into its dynamics. The convergence and stability of the proposed observer and controller are established using contraction analysis. Experimental results show that the proposed approach exhibits satisfactory performance.

Electric vehicles (EVs) are an alternative to internal combustion engine (ICE) cars, as they can reduce the environmental impact of transportation. The bottleneck for EVs is the high-voltage battery pack, which utilizes most of the space and increases the weight of the vehicle. Currently, the main challenge for the electronics industry is the cell equalization of the battery pack. This paper gives an overview of the research works related to battery equalizer circuits (BECs) used in EV applications. Several simulations were carried out for the main BEC topologies with the same initial conditions. The results obtained were used to perform a quantitative analysis between these schemes. Moreover, this review highlights important issues, challenges, variables and parameters associated with the battery pack equalizers and provides recommendations for future investigations. We think that this work will lead to an increase in efforts on the development of an advanced BEC for EV applications.