Mechatronic Systems Research Articles

A Portable Six-Wheeled Mobile Robot With Reconfigurable Body and Self-Adaptable Obstacle-Climbing Mechanisms

Abstract Mobile robots can replace rescuers in rescue and detection missions in complex and unstructured environments and draw the interest of many researchers. This paper presents a novel six-wheeled mobile robot with a reconfigurable body and self-adaptable obstacle-climbing mechanisms, which can reconfigure itself to three locomotion states to realize the advantages of terrain adaptability, obstacle-crossing ability, and portability. Design criteria and mechanical design of the proposed mobile robot are first presented, based on which the geometry of the robot is modeled and the geometric constraint, static conditions, and motion stability condition for obstacle crossing of the robot are derived and formulated. Numerical simulations are then conducted to verify the geometric passing capability, static passing capability, and motion stability and to find feasible structure parameters of the robot in obstacle crossing. Further, a physical prototype of the proposed mobile robot is developed and integrated with mechatronic systems and remote control. Using the prototype, field experiments are carried out to verify the feasibility of the proposed design and theoretical derivations. The results show that the proposed mobile robot satisfies all the criteria set and is feasible for applications in disastrous rescuing scenarios.

Energy-based nonlinear dynamical modeling of dielectric elastomer transducer systems suspended by elastic structures

This paper presents the Hamilton principle approach to model, design and control mechatronic systems using dielectric elastomer transducers (DET) suspended with elastic structures. An overall dynamical modeling approach for dielectric elastomer-based actuators is presented, taking into account the dynamical effects, e.g., electrical input quantities, inertia, viscous effects, and the nonlinear behavior of DETs and elastic structures. Energy-based techniques are used to obtain a coherent modeling of the electrical and mechanical domains. Based on the variational principle and using the Rayleigh–Ritz method to approximate the field variable, a nonlinear state space model is derived considering various geometric deformations and boundary conditions. The presented approach leads to a set of ordinary differential equations that can be used for control and engineering applications. The proposed method is finally applied to a multilayer DET coupled with a nonlinear buckled beam structure and analyzed based on analytical considerations and numerical simulations.

Adaptive Fuzzy Control for Uncertain Mechatronic Systems With State Estimation and Input Nonlinearities

In the field of practical engineering, the performance of mechatronic systems is influenced by model uncertainties, velocity unavailability, input nonlinearities (e.g., actuator deadzones/faults), etc.Moreover, some complex nonlinear dynamics do not satisfy the linear parameterization condition. Hence, due to intractable approximation errors, some existing controllers may obtain <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">only</i> uniformly ultimately bounded results and require velocity feedback to accomplish online estimation. To overcome the aforementioned obstacles, this article designs a new output feedback controller to fulfill accurate trajectory tracking and obtain state estimates for a class of Euler–Lagrange (EL) mechatronic systems. Specifically, we first construct a group of auxiliary variables to accurately recover velocities <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">without</i> numerical differential operations. Then, by employing <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">only</i> the available output information, unknown model knowledge and actuator deadzones/faults are simultaneously approximated online; more importantly, the asymptotic stability of the system equilibrium point is guaranteed by strict theoretical analysis. Another merit of the proposed controller is that the approximation errors are addressed in a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">new way</i> , where <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">no</i> discontinuous robust terms are required; hence, the chattering problem is effectively alleviated. To the best of our knowledge, for uncertain EL mechatronic systems with actuator deadzones/faults, this article proposes the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">first</i> solution to eliminate tracking errors and accurately recover unmeasurable states by <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">continuous</i> control signals. The asymptotic convergence of closed-loop signals is proven based on Lyapunov methods, and the performance of the proposed controller is validated by hardware experiments.

Method of faults identification in non-stationary systems

The article presents a new method for faults identification in mechatronic systems, described by non-stationary nonlinear differential equations, in the presence of perturbations. Observers working in a sliding mode are used to solve the problem. The proposed approach is based on the idea of constructing a reduced (with lower dimension) model of the original system with selective sensitivity to faults and disturbances. The main purpose of introducing such a model is the ability to take into account the nonstationarity of the system. The stated theory is illustrated by a practical example. Key words Fault identification, non-stationary systems, observers. Acknowledgements The work was supported by the Russian Foundation for Basic Research (project no. 20-38-70161), and also partially by the grant of the President of the Russian Federation, SP-3252.2019.5.

Adjustable suspension system for lower limb prosthesis

The contact between the stump and the lower limb prosthesis has to be provided by its suspension system. The paper presents a solution for an adjustable suspension designed as an inflated cell network. Each cell is supplied with controlled pressure and consequently, a contact force with the skin is developed. By varying the pressure value inside the cell, we may provide variable force, so the compensation for the volume change of the stump could be accomplished. The material the cells are made of should have special properties, the elasticity being the most important. Moreover, the goal of the paper was to approve the opportunity to use the silicone rubber Zhermack for the cell material and a mechatronic system has been realised as experimental set-up.

Longitudinal Dynamic Modeling and Driving Cycle Tracking Control of an Electric-Driven Vehicle by Means of MATLAB/Simulink/Simscape

MATLAB, Simulink, and Simscape are market-leading products in Model-Based Design (MBD). Applying acausal and causal modeling methods to model the physical plant and control algorithms of mechatronic systems results in high-fidelity virtual prototype models that can be used for Model-in-Loop (MiL) development. In this paper, an electric-driven vehicle is modeled, which can execute various driving cycle inputs. PID controllers are used in order to get the appropriate plant inputs. Idealized anti-lock braking system (ABS) and traction control system (TCS) algorithms provide robustness when the driving cycle input is near-infeasible. The control algorithm is validated in the cases of feasible and infeasible driving cycle inputs.

Design and Implementation of a Ball-Plate Control System and Python Script for Educational Purposes in STEM Technologies.

This paper presents the process of designing, fabricating, assembling, programming and optimizing a prototype nonlinear mechatronic Ball-Plate System (BPS) as a laboratory platform for engineering education STEM. Due to the nonlinearity and complexity of BPS, the task presents challenges such as: (1) difficulty in controlling the stabilization of a particular position point, known as steady-state error, (2) position resolution, known as specific distance error, and (3) adverse environmental effects—light-shadow error, which is also discussed in this paper. The laboratory prototype BPS for education was designed, manufactured and installed at Karlovac University of Applied Sciences in the Department of Mechanical Engineering, Mechatronics program. The low-cost two-degree BPS uses a USB HD camera for computer vision as a feedback sensor and two DC servo motors as actuators. Due to control problems, an advanced block diagram of the control system is proposed and discussed. An open-source control system based on Python scripts, which allows the use of ready-made functions from the library, allows the color of the ball and the parameters of the PID controller to be changed, indirectly simplifying the control system and performing mathematical calculations directly. The authors will continue their research on this BPS mechatronic platform and control algorithms.

New Approach for Failure Prognosis Using a Bond Graph, Gaussian Mixture Model and Similarity Techniques

This paper proposes a new approach for remaining useful life prediction that combines a bond graph, the Gaussian Mixture Model and similarity techniques to allow the use of both physical knowledge and the data available. The proposed method is based on the identification of relevant variables that carry information on degradation. To this end, the causal properties of the bond graph (BG) are first used to identify the relevant sensors through the fault observability. Then, a second stage of analysis based on statistical metrics is performed to reduce the number of sensors to only the ones carrying useful information for failure prognosis, thus, optimizing the data to be used in the prognosis phase. To generate data in the different system state, a simulator based on the developed BG is used. A Gaussian Mixture Model is then applied on the generated data for fault diagnosis and clustering. The Remaining Useful Life is estimated using a similarity technique. An application on a mechatronic system is considered for highlighting the effectiveness of the proposed approach.

Using two case studies to explore the applicability of VIATRA for the model-driven engineering of mechatronic production systems

The engineering of mechatronic production systems is complex and requires various disciplines (e.g., systems, mechanical, electrical and software engineers). Model-driven engineering (MDE) supports systems development and the exchange of information based on models and transformations. However, the integration and adoption of different modeling approaches are becoming challenges when it comes to cross-disciplinary work. VIATRA is a long-living enduring and mature modeling framework that offers rich model transformation features to develop MDE applications. This study investigates the extent to which VIATRA can be applied in the engineering of mechatronic production systems. For this purpose, two model transformation case studies are presented: “SysML – AutomationML” and “SysML4Mechatronics – AutomationML.” Both case studies are representative of structural modeling and interdisciplinary data exchange during the development of mechatronic production systems. These case studies are derived from other researchers in the community. A VIATRA software prototype implements these case studies as a batch-oriented transformation and serves as one basis for evaluating VIATRA. To report on our observations and findings, we built on an evaluation framework from the MDE community. This framework considers 14 different characteristics (e.g., maturity, size, execution time, modularity, learnability), according to the Goal-Question-Metric paradigm. To be able to evaluate our findings, we compared VIATRA to ATL. We applied all cases to a lab-size mechatronic production system. We found that, with VIATRA, the same functions for model transformation applications can be achieved as with ATL, which is popular for model transformations in both the MDE and the mechatronic production systems community. VIATRA combines the relational, imperative, and graph-based paradigms and enables the development and execution of model-to-model (M2M) and model-to-text (M2T) transformations. Furthermore, the VIATRA internal DSL is based on Xtend and Java, making VIATRA attractive and intuitive for users with less experience in modeling than in object-oriented programming. Thus, VIATRA leads to an interesting alternative for the model-driven engineering of mechatronic production systems. It has the potential to reduce the complexity during the development of model transformations. To conclude, this paper evaluates the applicability of VIATRA, its strengths and limitations. It provides lessons learned and insights that can stimulate further research in the MDE for mechatronic production systems.

Prediction of rail surface damage in locomotive traction operations using laboratory-field measured and calibrated data

Rail damage prediction is a complex task because it depends on numerous tribological parameters and the dynamic conditions produced by the vehicles operating at different speeds and configurations. Shakedown maps and Whole-Life-Rail-Model/T-Gamma have been used to predict rail damage, but they involve assumptions that may reduce their accuracy. This paper proposes a simulation modelling method to predict rail surface damage based on a locomotive digital twin, calibrated shakedown maps and friction measurements. The method improves the accuracy of rail damage predictions by including slip-dependent friction characteristics, co-simulation of locomotive traction mechatronic system and the mechanical properties of the wheel and rail materials measured through tensile tests. A set of operating conditions are simulated on a high-performance computing cluster, with stress results being post processed into calibrated shakedown heatmaps. The method clearly indicated the influences of the different operating conditions on rail damage for specific combinations of wheel-rail materials and vehicle-track configurations.

Developing Digital Observer of Angular Gaps in Rolling Stand Mechatronic System

Algorithms for monitoring the rolling mill mechatronic system state should be developed on the basis of modern digital technologies. Developing digital shadows (observers) of system state parameters in the periodic measurement mode is promising. This study relevance is defined by frequent emergency breakdowns of rolling stand mechanical transmissions. Most breakdowns are caused by worn end clutches (heads) of countershafts (spindles) transmitting rotation from the motor to the rolls. This is caused by elastic oscillations due to closing angular gaps when the metal enters the stand. The spindle joint angular gap increases over time with the mill operation. Therefore, it is an important diagnostic parameter that allows for an estimation of the transmission serviceability. In this regard, the problem of monitoring the angular gaps in the rolling stand mechatronic systems is relevant. The paper considers developing an observer of angular gaps in the spindle joints of the ‘electric drive-stand’ mechatronic system of the plate Mill 5000 of Magnitogorsk Iron and Steel Works PJSC (MMK PJSC). The monitored signal (angular gap) is calculated with the mathematical processing of the motor’s physical parameters (speed and electromagnetic torque), measured at a given frequency. The gap is determined indirectly by integrating the speed during its closing. To achieve this, the speed is controlled according to the triangular tachogram at no load. The stand’s electromechanical system modes have been studied using mathematical simulation. The observer’s practical use expediency has been reasoned. The structure of the observer-based angular gap monitoring information system is given. The system has been full-scale tested on Mill 5000, which has confirmed the developed algorithm efficiency. The study’s contribution is a justified and implemented concept of a relatively simple technical solution that can be commercially implemented without extra costs. The angular gap calculation algorithm does not involve complex mathematical techniques and can be implemented in industrial rolling mill controllers. Monitoring is automated without human involvement, which eliminates the human factor. The solution has a specific practical focus and is recommended for implementation at operating rolling mills.

Small Magnus Wind Turbine: Modeling Approaches

Renewables have passed the peak of the inflated expectation hype cycle for emerging technologies, but interest in the design of new energy conversion devices is still high due to widespread distributed energy systems for private households. Magnus effect-based wind turbine combines mechanical and electronic engineering that provides a broader wind speed range and potential maximum power point tracking for deeper grid integration. This paper provides a comparative analysis of Magnus effect-based wind turbine simulation models and the development of the numerical model for the maximum power point tracking algorithm. The advanced model contributes to the reduction of the number of actual tests required for the mechatronics system tuning and deals with sustainability-related challenges, such as climate change and the development of new renewable sources of energy.

Offline adaptation of co-simulation time steps by leveraging past co-simulation runs in multi-level mechatronic systems

Modeling and simulation of mechatronic systems require a multi-disciplinary approach as several physical domains interact with each other. Due to this heterogeneity, each domain can benefit from a dedicated time integration strategy as well as modeling formalism to control the error in simulation and reduce computational overhead. Current multi-rate adaptive time-stepping approaches disregard the system dynamics knowledge obtained in previous simulations and adapt the time steps at run-time as a black-box model. Although current multi-rate adaptive time-stepping approaches do not exploit the time scale of the physics of each domain, this information can be exploited in co-simulations by having a predefined multi-rate time integration approach in design space exploration and parameter identification applications, which involve repeated simulations with similar dynamics. In this study, an offline adaptive co-simulation technique is introduced. The proposed method adapts the communication and time integration time steps before the simulation using the estimated error data from past co-simulation runs. The offline adaptive co-simulations performed faster against the run-time adaptive co-simulations for comparable accuracy levels in 1D and multi-level mechatronic systems with changing loading and initial conditions.

Depth Map Reconstruction Method in Control Problems for Robots and Mechatronic Systems

In modern robotic and mechatronic systems, technologies are in demand that makes it possible to build an optimal trajectory of movement of their actuators. Such technologies are formed by combining navigation methods and building a 3-D map of the surrounding space based on vision systems and are successfully used in robotics and mechatronics. But there is a problem, consisting of a decrease in the accuracy of planning the trajectory of movement, caused by incorrect sections on the map (depth map) due to incorrect determination of the distance to objects. Such defects appear as a result of poor lighting, specular or fine-grained surfaces of objects. This leads to the impossibility of obtaining reliable information about the depth. As a result, the effect of increasing the boundaries of objects (obstacles) appears, and the overlapping of objects makes it impossible to distinguish one object from another. This problem can be solved using image reconstruction methods. The article presents an approach based on a modified algorithm for searching for similar blocks using the concept of quaternions and anisotropic gradient. The analysis of the research results shows that the proposed method allows you to correctly restore the boundaries of objects on the depth map image when reconstructing 3-D scenes, which contributes to an increase in the accuracy of planning the trajectory of motion of the actuators robotic and mechatronic systems.

Development and analysis of a mechatronic system for in-process monitoring and compensation of straightness deviation in BTA deep hole drilling

In BTA deep hole drilling straightness deviation of the bore is a very important quality criteria. The avoidance of straightness deviation is not possible due to the many influencing variables. Currently used methods for compensation require significant additional time, as they either require the interruption of the drilling process, or require an additional boring process. By using a newly developed, manufactured and tested compensation unit, which is mounted between the drill head and the drill pipe, a targeted tilting of the drill head and thus a targeted influencing of the straightness deviation in the running process is possible with the use of a radially adjustable control pad and an innovative actuator concept. The developed measuring system offers the possibility to record the straightness deviation during the drilling process. On the basis of experimental test series, a control system was developed and applied to the BTA deep drilling process. After a drilling path of 1,000 mm, a maximum straightness deviation reduction of approx. 51% can be realized. Compared to the process without control and compensation unit, the progressive increase of the straightness deviation was significantly reduced.

PSpSys: A time-predictable mixed-criticality system architecture based on ARM TrustZone

In mixed-criticality systems, components often have different criticality requirements that must be met. Components with different criticality requirements must be partitioned into independent execution domains with robust inter-domain isolation, in order to prevent interference between domains of different criticality. For the most critical components, timing-predictability and performance/efficiency are key in ensuring the correct execution of critical components. Existing approaches achieve the required inter-domain isolation using either virtualisation technology or a hardware isolation environment. However, these approaches often conflict with the required timing-predictability and performance/efficiency of components with the highest criticality, which originates from (i) the introduction of complicated system architectures; (ii) the neglection of partitioning and multiplexing of I/Os; (iii) the lack of bounded worst-case timing. In this article, we propose a new mixed-criticality system architecture based on ARM TrustZone technology, termed P arallel Sp ace Sys tem ( PSpSys ), which is a timing-predictable system architecture with hardware-level isolation and predictable inter-domain shared I/O management. In addition, an alternative co-processor is also proposed for PSpSys , which significantly improves performance with reduced system complexity. PSpSys therefore can be applied to safety-critical mechatronic systems (e.g. unmanned autonomous systems, field robotics) which perform tasks on different critical levels. Finally, we demonstrate how PSpSys can be exploited to achieve all the required features in real hardware platform (Xilinx ZC706 evaluation board).

Application of the Half-Order Derivative to Impedance Control of the 3-PUU Parallel Robot

This paper presents an extension of impedance control of robots based on fractional calculus. In classical impedance control, the end-effector reactions are proportional to the end-effector position errors through the stiffness matrix K, while damping is proportional to the first-order time-derivative of the end-effector coordinate errors through the damping matrix D. In the proposed approach, a half-derivative damping is added, proportional to the half-order time-derivative of the end-effector coordinate errors through the half-derivative damping matrix HD. The discrete-time digital implementation of the half-order derivative alters the steady-state behavior, in which only the stiffness term should be present. Consequently, a compensation method is proposed, and its effectiveness is validated by multibody simulation on a 3-PUU parallel robot. The proposed approach can be considered the extension to MIMO robotic systems of the PDD1/2 control scheme for SISO mechatronic systems, with potential benefits in the transient response performance.

Special issue on computational intelligence-based modeling, control and estimation in modern mechatronic systems

Special issue on computational intelligence-based modeling, control and estimation in modern mechatronic systems

Optical-based sensing of shear strain using reflective color patterns

There is an increasing need to measure shear stress and strain for biomedical and robotics applications. Many shear sensors exist, but are often impractical for these applications as they can be bulky, require wired power sources, or are sensitive to electromagnetic interference from the human body or mechatronic systems. This paper presents an optical-based sensor, which measures shear strain based on a red, green, and blue (RGB) light-emitting diode (LED) projecting a cyclical pattern of RGB light onto a color pattern. As shear strain causes displacement between the LED and color pattern, the relative intensities of the reflected RGB lights change due to the shift of the color pattern position. A photoresistor captures the reflected light intensity during each color illumination, allowing determination of shear strain along two axes. The purpose of this work was to determine the optimal sensor configuration by studying the efficacy of different color patterns and data classification algorithms to measure two-axis shear strain. The optimal sensor configuration was a randomized color pixel pattern with a weighted k-nearest-neighbor classifier. Accuracy was 97.5% and 98.0%, and misclassification cost was 0.11 mm and 0.07 mm in the horizontal and vertical directions, respectively. Importantly, this sensing technique allows determination of directionality of shear measurement, overcoming a major limitation of other optical-based shear sensors. These properties, along with its small, low-cost, and scalable design support the use of this sensor and sensing paradigm for a variety of biomedical and robotics applications

Calculation Structural Model of Engine for Nanobiomedicine

The structural model of the electroelastic engine for nanobiomedicine is determined. The structural scheme of the engine is constructed. For the mechatronics systems with the elecroelastic engine its deformations are obtained.