Mechatronic Design Research Articles

Versatile Dynamic Motion Generation Framework: Demonstration With a Crutch-Less Exoskeleton on Real-Life Obstacles at the Cybathlon 2020 With a Complete Paraplegic Person.

Lower-limb exoskeletons are a promising option to increase the mobility of persons with leg impairments in a near future. However, it is still challenging for them to ensure the necessary stability and agility to face obstacles, particularly the variety that makes the urban environment. That is why most of the lower-limb exoskeletons must be used with crutches: the stability and agility features are deferred to the patient. Clinical experience shows that the use of crutches not only leads to shoulder pain and exhaustion, but also fully occupies the hands for daily tasks. In November 2020, Wandercraft presented Atalante Evolution, the first self-stabilized and crutch-less exoskeleton, to the powered exoskeleton race of the Cybathlon 2020 Global Edition. The Cybathlon aims at promoting research and development in the field of powered assistive technology to the public, contrary to the Paralympics where only participants with unpowered assistive technology are allowed. The race is designed to represent the challenges that a person could face every day in their environment: climbing stairs, walking through rough terrain, or descending ramps. Atalante Evolution is a 12 degree-of-freedom exoskeleton capable of moving dynamically with a complete paraplegic person. The challenge of this competition is to generate and execute new dynamic motions in a short time, to achieve different tasks. In this paper, an overview of Atalante Evolution system and of our framework for dynamic trajectory generation based on the direct collocation method will be presented. Next, the flexibility and efficiency of the dynamic motion generation framework are demonstrated by our tools developed for generating the important variety of stable motions required by the competition. A smartphone application has been developed to allow the pilot to choose between different modes and to control the motion direction according to the real situation to reach a destination. The advanced mechatronic design and the active cooperation of the pilot with the device will also be highlighted. As a result, Atalante Evolution allowed the pilot to complete four out of six obstacles, without crutches. Our developments lead to stable dynamic movements of the exoskeleton, hands-free walking, more natural stand-up and turning moves, and consequently a better physical condition of the pilot after the race compared to the challengers. The versatility and good results of these developments give hope that exoskeletons will soon be able to evolve in challenging everyday-life environments, allowing patients to live a normal life in complete autonomy.

An Innovative Optimization Design Procedure for Mechatronic Systems with a Multi-Criteria Formulation

This paper presents an innovative Mechatronic Concurrent Design procedure to address multidisciplinary issues in Mechatronics systems that can concurrently include traditional and new aspects. This approach considers multiple criteria and design variables such as mechanical aspects, control issues, and task-oriented features to formulate a concurrent design optimization problem that is solved using but not limited to heuristic algorithms. Furthermore, as an innovation, this procedure address all considered aspects in one step instead of multiple sequential stages. Finally, this work discusses an example referring to Mechatronic Design to show the procedure performed and the results show its capability.

A novel design on polymeric material recycling technology

The necessity for recycling of wastes has increased nowadays and there are various solutions according to the types of wastes which are presented accordingly. By observing these solutions, the recycling system from the waste collection and separation system of the long-term disappearing of polymer waste to the additive manufacturing design stage has been indicated. Waste collection and separation systems have been reviewed and systems to be used effectively in the systematic way have been exemplified. Among four different separating systems which are with rotating, rail and fixed containers, fixed container four-sorting waste separation systems were chosen and developed as a mechatronic system design. The mechatronic system design is very prominent in order to create efficient and economical mechanisms in fixed-container four-sorting waste separation collection system (FCWS) applications. In addition, physical mechatronic system design (MSD), mechanical design, material selection, electrical electronic design sub-heading and cost analysis were made. In this study, the necessity and importance of the waste separation plants are revealed

Design and analysis of a novel tendon-driven continuum robotic dolphin

In this paper, a novel continuum robotic dolphin termed ‘ConRoDolI’ is proposed and developed. The biomimetic robot features dual tendon driving continuum mechanisms that are utilized to replicate the twisting and bending motions of the dolphin’s caudal vertebrae and thoracic vertebrae. More importantly, a central pattern generator based kinematics is analyzed to yield stable dolphin-like swimming. In the meantime, the relationship between the backbone shape and both the tendon length as well as position and orientation are explored. Furthermore, multimodal swimming gaits are designed to pave the way for a three-dimensional (3D) swimming decoupling solution, involving forwarding swimming, multiple yaw patterns, and multiple pitch patterns. All of these endow the robotic dolphin with 3D maneuverability. Finally, extensive experiments demonstrate the feasibility of the proposed biomimetic mechatronic design and control approach. The forward swimming speed is 0.44 body lengths per second (BL/s). The steering radius of the robot is about 0.11 BL with an angular velocity of 10°/s and the diving speed is about 0.13 BL/s. The average propulsion efficiency is about 0.6 with the maximum is over 0.8. The obtained results shed light on the improvement of aquatic maneuverability associated with new-concept underwater vehicles.

Synchronized switch piezoelectric energy harvesting using rotating magnetic ball and reed switches

Synchronized switch harvesting on inductor (SSHI) interface circuit has been developed to boost the harvesting capability of piezoelectric energy harvesters (PEHs). Although some electronic self-powered peak-detector and switching circuits have been proposed to support the practical realization of SSHI, the energy dissipation and voltage drops in transistors and diodes of the self-powered circuits might significantly deteriorate the actual energy harvesting performance. Some mechatronic designs were proposed as well. However, most of their switches are activated by touch impacts, which might introduce undesired high-order vibrations to the main structure. In this paper, rather than using the impact-engaged strategy discussed in the literature, a new mechanism using a magnetic ball for vibration synchronization and reed switches for switching operation is proposed. A PEH shunted to an SSHI interface circuit using the proposed mechatronic approach has been prototyped. Since the peak-detection and switching operations are completed by a mechanical mechanism, less passive electrical components, which consume extra energy, are required in our proposed design. Therefore, the overall energy harvesting performance is improved. Numerical simulations and experimental tests have validated the feasibility of the proposed design. The experimental results have shown that the power output produced by the proposed mechatronic self-powered SSHI design can be increased by and , as compared with the cases using a benchmark standard energy harvesting bridge rectifier and an electronic self-powered SSHI solutions, respectively. Moreover, owing to the new mechatronic design, the auxiliary mechanical components are embedded in the tip block of the cantilevered PEH, rendering the whole system to be a compact design.

System design and control of an apple harvesting robot

There is a growing need for robotic apple harvesting due to decreasing availability and rising cost in labor. Towards the goal of developing a viable robotic system for apple harvesting, this paper presents synergistic mechatronic design and motion control of a robotic apple harvesting prototype, which lays a critical foundation for future advancements. Specifically, we develop a deep learning-based fruit detection and localization system using a RGB-D camera. A three degree-of-freedom manipulator is designed with a hybrid pneumatic/motor actuation mechanism to achieve dexterous movements. A vacuum-based end-effector is used for apple detaching. These three components are integrated into a robotic apple harvesting prototype with simplicity, compactness, and robustness. Moreover, a nonlinear control scheme is developed for the manipulator to achieve accurate and agile motion control. Field experiments are conducted to demonstrate the performance of the developed apple harvesting robot.

Simulation and optimization of automated masonry construction using cable robots

A cable-driven parallel robot for automated masonry construction is currently under development. Besides the mechatronic design and component engineering, a simulation framework has been realized to optimize the cable robot motions with respect to technical and economic requirements, which supports both the prediction of the potential and limitations of this approach as well as the reduction of the risk for further development activities.The framework generates suitable trajectories for every masonry unit to be placed, considering several requirements and optimization criteria. These include motion time, collision avoidance, stiffness, cable forces and energy requirements. The framework uses a hybrid particle swarm algorithm for global optimization.The paper presents the trajectory modeling and the definition of the cost functions derived from physical models of the cable robot. It includes the analysis of simulation results that illustrate the generated trajectories.

An Improved Method of Minimizing Tool Vibration during Boring Holes in Large-Size Structures.

The paper presents a thoroughly modified method of solving the problem of vibration suppression when boring large-diameter holes in large-size workpieces. A new approach of adjusting the rotational speed of a boring tool is proposed which concerns the selection of the spindle speed in accordance with the results of the simulation of the cutting process. This streamlined method focuses on phenomenological aspects and involves the identification of a Finite Element Model (FEM) of a rotating boring tool only and validating it with a real object, while dispensing with discrete modelling of a completely rigid workpiece. In addition, vibrations in the boring process in all directions were observed, which implies a geometric nonlinearity of the process model. During the simulation, the values of the Root Mean Square (RMS) of the time plots and the dominant values of the “peaks” in the displacement amplitude spectra were obtained. The effectiveness of the method was demonstrated using a selected mechatronic design technique called Experiment-Aided Virtual Prototyping (E-AVP). It was successfully verified by measuring the roughness of the indicated zone of the workpiece surface. The economic profitability of implementing the method in the production practice of enterprises dealing with mechanical processing is also demonstrated.

Swing-Reducing Flight Control System for an Underactuated Indoor Miniature Autonomous Blimp

This article presents the first swing-stabilization control for indoor miniature autonomous blimps (MABs). Indoor MABs are safe to operate in close proximities to humans and can fly for multiple hours, but swing oscillation is commonly observed due to their underactuated design and unique aerodynamic shape. In this article, we analyze the flight characteristics of indoor MABs, and describe the design of the swing-reducing flight control system in detail. Key mechatronic designs for swing-stabilization control are also presented. Experimental results show that the proposed controller can keep the blimp travel at the desired velocity while effectively stabilizing the swing oscillation. The swing-reducing velocity controller is then expanded for station keeping and waypoint navigation in a 3-D space.

Design and Control of a Two-Motor-Actuated Tuna-Inspired Robot System

This article presents the mechanical design and locomotion control of a novel tuna-inspired robot system for both fast swimming and high maneuverability. Mechanically, the developed robotic fish named CasiTuna comprises three important parts, i.e., an innovative two-motor-actuated propulsive mechanism, a buoyancy adjustment structure, and a pair of pectoral fins. Unlike most robotic fishes' multiple concatenated links-based propulsive mechanism, CasiTuna's two-motor-actuated one places both motors in the anterior body and utilizes a transmission system to achieve tuna-like lateral undulations. Meanwhile, the buoyancy adjustment mechanism in conjunction with pectoral fins endows the robot with the capability of three-dimensional maneuverability. Kinematic and dynamic analyses are further conducted to reveal the interactive hydrodynamic forces. Regarding the locomotion control method, a bio-inspired central pattern generator-based controller is adopted to achieve multimodal swimming. In particular, two kinds of turning maneuvers are implemented and discussed. Aquatic experiments, including straight swimming, circular turning, and nearly static pitching validate the effectiveness of proposed mechatronic design and locomotion control methods. Remarkably, CasiTuna achieved a peak forward speed of 0.8 m/s (corresponding to 1.52 body lengths per second) and a minimum turning radius of less than 0.3 body lengths.

Mechatronics Design and Kinematic Analysis of SMA Spring Actuated Parallel Manipulator

Flexible parallel manipulators can be used as an orienting device because of their precise positioning ability and better stiffness. The flexibility to the manipulator induces challenges in the selection of actuator, sensors and control. The paper presents a novel mechatronics design of a flexible symmetric parallel manipulator with minimum number of actuators used as an orienting device. Shape memory alloy springs (SMA) are used as an actuator because of ease of integration and higher deflection. In order to avoid any contact type sensor which could affect the compliance of the manipulator, the position of SMA spring is calculated indirectly from the kinematic model with the end effector orientation data measured from IMU sensor. The complete experimental set up design including electrical and control circuitry is explained in detail in the work. Preliminary open loop test is conducted on the prototype to understand the SMA response to various current input and to verify the effectiveness of the kinematic model in the actuator length measurement. Closed loop control based on ON/OFF control is implemented in the controller and is tested for step input.

Mechatronic Design of a Robot for Upper Limb Rehabilitation at Home

This paper addresses the design of a novel bionic robotic device for upper limb rehabilitation tasks at home. The main goal of the design process has been to obtain a rehabilitation device, which can be easily portable and can be managed remotely by a professional therapist. This allows to treat people also in regions that are not easily reachable with a significant cost reduction. Other potential benefits can be envisaged, for instance, in the possibility to keep social distancing while allowing rehabilitation treatments even during a pandemic spread. Specific attention has been devoted to design the main mechatronic components by developing specific kinematics and dynamics models. The design process includes the implementation of a specific control hardware and software. Preliminary experimental tests are reported to show the effectiveness and feasibility of the proposed design solution.

Efficient oscillation detection for verification of mechatronic closed-loop systems using search-based testing

In mechatronic system design, the systematic early-stage verification in simulation environments is a crucial aspect. In particular, the development of highly sophisticated and well performing controllers requires complementary testing by extensive simulations. The assessment and evaluation of the control strategy and its tuning is ideally carried out by specialists and is usually very time consuming. Due to time constraints, often only the nominal configuration and a limited number of other configurations are considered in the simulation-based analysis of the closed-loop system. To cover a more comprehensive set of test cases and speed up the analysis, assistive and automated tools are essential. This paper proposes a method to systematically search for oscillations in closed-loop mechatronic systems, which, in most cases, indicate a poor control performance or even an unstable system behavior. Although oscillation detection methods are very well established in the process industry, these methods do not directly apply to mechatronic systems where frequent changes of the operating points and tracking of fast trajectories have to be taken into account. A recently proposed method which can cope with these challenges uses the Empirical Mode Decomposition (EMD) combined with an assessment of the decomposed modes. This is the basis for the construction of a normalized and continuous oscillation index, which provides a suitable measure for the oscillation strength. The performance of the selected EMD approach compared to other state-of-the-art concepts is illustrated by measurement data of a hydraulic valve. The introduced oscillation index serves as an objective function for a Search-based Testing (SbT) approach to systematically select those parameter combinations which yield a worst-case scenario for the closed-loop system. The high potential of the combination of SbT with an oscillation-based objective function for the automated verification of closed-loop mechatronic systems is demonstrated for the example of a goods lift.

Mechatronic Design and Active Disturbance Rejection Control of a Bag Valve-Based Mechanical Ventilator

Abstract This paper presents the mechatronic (mechanical and control system) design of a functional prototype of a portable mechanical ventilator to treat patients with a compromised respiratory function. The portable ventilator ensures adequate oxygenation and carbon dioxide clearance while avoiding ventilator-induced lung injury (VILI). Oxygen is delivered through the compression of a bag valve (Ambu bag) using a moving strap. Carbon dioxide is cleared through the control of a pinch valve actuated by a low-torque servomotor. The positive end-expiratory pressure (PEEP) is controlled by an adjustable mechanical valve of the system. An Arduino Mega microcontroller board is used in this prototype to control the respiratory variables. All mechanical components as well as sensors, actuators, and control hardware are of common use in robotics and are very inexpensive. The total cost of the prototype built in this work is about $425 U.S. dollars. The design is meant to be replicated and utilized in emergency conditions that involve an overwhelming number of cases, such as COVID-19 treatment, in places with no access to commercial mechanical ventilation (MV) technologies. In order to account for variations in the prototype as built, the software developed for this portable MV applies an active disturbance rejection control (ADRC) strategy. This control strategy is presented as a universal control structure for any mechanical ventilator able to supply air flow with controlled pressure and volume.

Conflict Resolution in Mechatronic Collaborative Design Using Category Theory

Due to the multitude of disciplines involved in mechatronic design, heterogeneous languages and expert models are used to describe the system from different domain-specific views. Despite their heterogeneity, these models are highly interrelated. As a consequence, conflicts among expert models are likely to occur. In order to ensure that these models are not contradictory, the necessity to detect and manage conflicts among the models arises. Detecting these inconsistencies at an early stage significantly reduces the amount of engineering activities re-execution. Therefore, to deal with this issue, a formal framework relying upon mathematical concepts is required. The mathematical theory, namely category theory (CT), is considered as an efficient tool to provide a formal and unifying framework supporting conflict detection and management. This paper proposes a comprehensive methodology that allows conflict detection and resolution in the context of mechatronic collaborative design. CT is used in order to explicitly capture the inconsistencies occurred between the disparate expert models. By means of this theory, the conflicts can be detected and handled in an easy and formal way. Our proposed approach is applied to a collaborative scenario concerning the electro-mechanical actuator (EMA) of the aileron.

Employing Finite Element Analysis and Robust Control Concepts in Mechatronic System Design-Flexible Manipulator Case Study

The paper deals with development of a methodology for mechatronic system design using state-of-the-art model-based system engineering methods. A simple flexible robotic arm is considered as a benchmark problem for the evaluation of various techniques used in the phases of modelling, analysis, control system design, validation, and implementation. The flexible nature of the mechanical structure introduces inherently oscillatory dynamics in the target bandwidth range, which complicates all the above-mentioned design steps. This paper demonstrates the process of deriving a complex nonlinear model of the flexible arm setup. An initial idea about the plant dynamics is acquired from analytical modelling using the Euler–Bernoulli beam theory. A more thorough understanding is subsequently acquired from finite element analysis. Linearisation and order reduction are the next steps necessary for the derivation of a simplified control-relevant model. A time-dependent variable parameter of load mass position is considered and a robust controller is subsequently designed in order to fulfil certain performance criteria for all the admissible plant configurations. This is performed using a recent H-infinity loop shaping method for fixed structure controller design. The results are validated by means of a physical plant, comparing the experimental data with the model predictions.

Design and Locomotion Control of a Dactylopteridae-Inspired Biomimetic Underwater Vehicle With Hybrid Propulsion

This article presents the design and implementation of an innovative biomimetic underwater vehicle (BUV) and its locomotion controller. Through mimicking a dactylopteridae, the hybrid propulsion BUV is designed with two symmetrical bio-inspired long-fins and a double-joint fishtail. The mechatronic design of the dactylopteridae-inspired BUV with the pectoral long-fins and a double-joint fishtail is first provided. The two flexible long-fins compose the median and/or paired fin (MPF) propulsion, while the fishtail acts as the body and/or caudal fin (BCF) propulsion. Through the coordination of BCF and MPF propulsion modes, the BUV obtains excellent low-speed locomotion stability and also keeps high maneuverability. Moreover, the locomotion control methods based on central pattern generators (CPGs) model and fuzzy adaptive proportion integral differential (PID) are proposed for this BUV. In the end, the experimental results of the multimode motion and closed-loop motion control demonstrate the feasibility and effectiveness of the mechanism and the locomotion control system. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —The motivation behind this article is the design of a novel biomimetic underwater vehicle (BUV) that possesses low-speed locomotion stability and fast swimming ability, which is suitable for carrying relevant sensors to complete water quality monitoring, biological observation, underwater equipment inspection, underwater structure detection, and other marine tasks. Currently, BUVs are usually designed as only one propulsion mode by caudal fin or paired fins, which makes it difficult to have the advantages of both modes. In order to further study the problem, we designed a dactylopteridae-inspired BUV with the bilateral pectoral long-fins (providing low-speed locomotion stability) and a double-joint fishtail (providing fast swimming ability). A hybrid-driven motion control framework is presented for the BUV based on a central pattern generators (CPGs) model and fuzzy adaptive proportion integral differential (PID). A series of experiments suggests that the mechanism and the locomotion control system are practical and valid. Hopefully, our mechanism and control framework can provide valuable theoretical and technical support guidance to the practicing marine engineer for the codesign of propulsion mode and control.

Guest Editorial Focused Section on Mechatronics in Unmanned Systems

The papers in this special section focus on the use of mechatronics in unmanned systems. During the past few decades, unmanned systems have widely been applied in the environs of aerospace, ground, surface, and underwater. It is expected that unmanned systems will have more pervasive applications in industry, military, agriculture, logistics, etc.,when advanced mechatronic technologies are combined with complex systems engineering. Mechatronic design offers feasible solutions for unmanned systems to operate robustly and efficiently under diverse and difficult environmental conditions, but brings challenges for design, sensing, and control. Facing the growing application demands, this subject has drawn increasing attention in recent years. For this reason, the design, implementation, modeling, control, and optimization of unmanned systems have become urgent issues. This focused section aims to report the latest research results, both theoretical and application-oriented and to emphasize mechatronics in unmanned systems, including mechanism design and optimization of unmanned systems, modeling and control of unmanned systems, bioinspired mechatronics in unmanned systems, applications of mechatronic for unmanned systems, etc. Topics explored in this focused section include, but be not limited to, theoretical foundations for mechatronics in unmanned systems, mechatronics design of the unmanned systems, mechanism design, fabrication and optimization of unmanned systems, modeling, identification, sensing, and control of unmanned systems, mechatronics in unmanned space/aerial/ground/surface/underwater vehicles, bioinspired mechatronics in unmanned systems, and applications of mechatronics for unmanned systems in industry/ military/agriculture/logistics.

Mechatronic Re-Design of a Manual Assembly Workstation into a Collaborative One for Wire Harness Assemblies

Nowadays, the wire harness assembly process is still manually performed due to the process complexity and product variability (e.g., wires of different kind, size and length). The Wire cobots project, in which this work was conceived, aims at improving the current state-of-art assembly process by introducing in it collaborative robotics. A shared workstation exploiting human abilities and machine strengths was developed to assembly automotive wire harness by means of insulated tape for a real industrial case. In the new workstation, the human deals with the complex task of wire handling, while the robot performs the repetitive and strenuous taping operations. Such a task allocation together with the workstation redesign allow for an improvement of the operator’s well-being in terms of postural conditions and for an increase of the production efficiency. In this paper, the mechanical and mechatronic design, as well as the realization and validation of this new collaborative workstation are presented and discussed.

Open-Design for a Smart Cover of a Night-Time Telescope for Day-Time Use

Robotic observatories are ideal infrastructures that can be remotely accessed by scientists, amateurs, and general public for research and education in Astronomy. Its robotization is a complex process for ensuring autonomy, safety, and coordination among all subsystems. Some observatories, such as Francisco Sanchez’s, are equipped with two types of telescopes: one for the night and one for the day. The night-time telescope must be protected from exposure to sunlight in order to use them in an automated way. For this purpose, this article proposes the design and construction of a smart cover that opens and closes according to the time of day. The mechatronic design covers the electronic, mechanical, and software programming, and it has been devised taking while taking the principles of open design, ease of reproduction, low-cost, and smart behaviour into account. The design has been parameterized, so that it can be adapted to telescopes of any size. The final prototype is lightweight, cost-effective, and can be built while using common 3D printing and PCB milling machines. The complete design is licensed under the GNU General Public License v3.0 and all the documentation, schematics, and software are available in public repositories, like Zenodo, GitHub, and Instructables.