Design of Mechanism is a standard subject in Mechatronics and Mechanical Engineering majors. Different methods and tools are used by lecturers to teach the subject. In this work, we investigate the impact on the competencies development by implementing a project-based learning methodology in a mechanism course. For this, we analyze the performance of students from two different groups. The first group is taught in a traditional fashion developing a final project just related to the discipline, and the second group is taught in a multidisciplinary context where the final goal is to develop a complex project where the mechanisms subject is one complementary subject with the others. The development of engineering competencies, declared for this course, is presented for both groups through the evaluation of different aspects; also, a survey of satisfaction from the students of both groups is presented. Overall, the results show that the multidisciplinary project-based learning method, having a nonacademic training partner as sponsor and solving a real nonacademic project, improves the development of competencies related to practical applications and increases the motivation and appreciation of the student towards the mechanism learning discipline.

Mixed reality (MR) laboratories combine physical elements with virtual components, providing convenient experiential environments for testing engineering concepts. This article reports the design, validation, and implementation of an MR laboratory for engineering students to practice the implementation of control algorithms in microcontrollers. First, the design of the MR lab is described in detail. In this, a seesaw electromechanical system is emulated, being synchronized with electrical signals that represent sensors’ measurements and actuators’ commands. Thus, a control algorithm implemented by the students in a microcontroller can affect the simulated system in real time. The real seesaw system was used to validate the simulated plant in the MR lab, finding that the same control algorithm effectively controls both the simulated and physical seesaw systems. A practice, designed based on Kolb’s experiential learning cycle, where the students must implement P, PI, and PID controllers in the MR lab, was implemented. A survey was conducted to assess the students’ motivation, and a post-test was administered to evaluate their learning outcomes.

In this work steady-state throughput changes due to firing rate variations in timed continuous Petri nets with infinite server semantics are considered. Two peculiar behaviors may appear: discontinuities and non-monotonicities. None of them are possible in Mono-T-Semiflow (MTS) nets when a certain structural condition, defined on the basis of the steady-state marking, is fulfilled. This work investigates the relation between discontinuities and non-monotonicities when the mentioned condition is not satisfied. First, using a graph-based perspective, such condition is classified using structural objects of the net. Then, the system throughput under firing rate variations is studied taking advantage of this classification. The equivalence between monotonicities and the structural condition is derived, whilst a counterexample shows that for discontinuities the implication goes in one way.

Increasing the production in manufacturing systems is one of the main demands in modern systems. The naive approach that this goal can be achieved when more or faster resources are used is not always valid. In fact, the complex interactions among system’s elements may lead to paradoxical behaviors; for example, using faster machines could reduce the equilibrium throughput (number of part fabricated per unit time in steady state) of the system, or even worse, block all system activities, reducing it to zero. This work leverages the concepts about fluidization and analysis techniques used in Timed Continuous Petri nets (TCPN) presented in earlier works to study the behavior of the equilibrium throughput when more/faster machines are used. Herein, we illustrate how discontinuities induced bifurcations of the equilibrium throughput are due to the existence of paths that can increase/decrease the marking of certain subnets. In particular, if paths gaining/losing tokens are fired without a particular balance, then the equilibrium throughput exhibits discontinuities since the equilibrium marking loses hyperbolicity. Moreover, these discontinuities imply other undesired throughput behaviors; for example, the existence of non-monotonicities of the equilibrium throughput (when more/faster resources are used in the system, its equilibrium throughput is reduced). The discontinuities together with a homothecy property are used to explain non-monotonicities in the equilibrium throughput. A relevant aspect is that these undesired system behaviors appear when the net has structural objects named problematic configurations that are associated with certain subnets in which there are no P-semiflows. Although the number of these configurations increase exponentially in the size of the net, some reduction rules are introduced to remove configurations, while the problematic ones are kept (or can be recovered) in the reduced net. This saves computation time in the analysis and, more importantly, provides useful insights about the root of undesired behaviors. This work focus on systems that can be modeled with fluid (or continuous) mono T-semiflow Timed Continuous Petri nets. Even if under certain constraints, they are capable of capturing many characteristics of modern systems, such as interleaving of cooperation and competition.

This work is concerned with the problem of translating an ordinary differential equation (ODE) with an attractor into a Timed Continuous Petri Net (TCPN) with product semantics. The proposed translation methodology starts by shifting the ODE attractor to a suitable value such that the system evolution is confined to the first orthant (i.e. the evolution will be positive). In the proposed methodology, a state x _i is represented by a place p _i . When the derivative of a state x _i depends on positive or negative terms of x _i , then input or output transitions are added to p _i to represent the positive or negative terms respectively. If the derivative of x _i depends on positive terms of other state variable x _j then a transition going from p _j to p _i is added. If the derivative of x _i depends on negative terms of other state variable x _j , then a subnet removing the appropriate marking from p _i is added. In order to illustrate this methodology, we show how the well known chaotic Rossler system is translated into a TCPN.