Mechanical Structure System Research Articles

Research on parameter matching characteristics of pneumatic launch systems based on co-simulation

AbstractPneumatic launch systems for Unmanned Aerial Vehicles (UAVs), including mechanical and pneumatic systems, are complex and non-linear. They are subjected to system parameters during launch, which leads to difficulty in engineering research analysis. For example, the mismatch between the UAV parameters and the parameter design indices of the launch system as well as the unclear design indices of the launching speed and overload of UAVs have a great impact on launch safety. Considering this situation, some studies are presented in this paper. Taking the pneumatic launch system as a research object, a pneumatic launcher dynamic simulation model is built based on co-simulation considering the coupling characteristics of the mechanical structure and transmission system. Its accuracy was verified by laboratory test results. Based on this model, the paper shows the effects of the key parameters, including the mass of the UAV, cylinder volume, pressure and moment of inertia of the pulley block, on the performance of the dynamic characteristics of the launch process. Then, a method for matching the parameter characteristics between the UAV and launch system based on batch simulation is proposed. The set of matching parameter values of the UAV and launch system that satisfy the launch take-off safety criteria are calculated. Finally, the influence of the system parameters of the launch process on the launch performance was analysed in detail, and the design optimised. Meaningful conclusions were obtained. The analysis method and its results can provide a reference for engineering and theoretical research and development of pneumatic launch systems.

Development of amplification system for point-of-care test of nucleic acid

Nucleic acid testing (NAT) has been widely used in many fields such as medical diagnosis, food safety testing and forensic identification. However, it can only be carried out in professional laboratory because the test process is complicated and rigorous. In this paper, a nucleic acid amplification system based on polymerase chain reaction (PCR) was developed to meet the requirements of point-of-care testing (POCT) for nucleic acids. Firstly, the mechanical structure and electronic control system were designed and constructed. Secondly, an integral separation PID algorithm for temperature control and an intelligent temperature compensation method based on support vector regression (SVR) were proposed. Finally, temperature measurement and biological experiments were performed to prove the stability and availability of the nucleic acid amplification system. The results showed that the system achieved a rapid temperature change velocity of 4.5 °C/s, and the steady-state error was within ± 0.5 °C. The nucleic acids in samples of different concentrations were well amplified, the system can be used for quantitative detection of nucleic acid with the help of a fluorescence detection system, and has higher sensitivity than Tianlong PCR instrument.

Research and Design of Household Intelligent Mechanical Claw

In order to design a kind of intelligent mechanical claw for home and office scene. Based on the investigation, analysis and arrangement of the features of items in the family and the functional demands of the family on the mechanical claw, a design scheme of intelligent mechanical claw which can switch functions and grasping modes according to the different grasping objects is proposed. Mechanical structure design, including mechanism motion design, part structure design, and use Autodesk Inventor software for mechanical parts, component design and simulation assembly; The stress analysis module in Autodesk Inventor was used to simulate the key components. Finally, the design scheme of mechanical structure and control system for the mechanical claw are proposed.

Research on the Drop Hammer Impact Test System

The drop hammer impact test system adopts the multi-purpose and modular design to solve the four problems of the airbag door of automobile test instrument panel: the test conditions are generally inconsistent with the actual conditions; The secondary impact problem exists in the collision test. The experiment does not have the experimental data, cannot provide the technical question for the enterprise; There are some problems in the equipment construction mode, such as universality, repeatability and low utilization rate. The improvement of mechanical structure and control system makes the device simple in structure, powerful in function, able to obtain accurate experimental data, and able to realize the instrument panel airbag door detection of different vehicle models.

Development and Evaluation of a Rehabilitation Wheelchair with Multiposture Transformation and Smart Control

Stroke and other neurological disorders have an effect on mobility which has a significant impact on independence and quality of life. The core rehabilitation requirements for patients with lower limb motor dysfunction are gait training, restand, and mobility. In this work, we introduce a newly developed multifunctional wheelchair that we call “ReChair” and evaluated its performance preliminarily. ReChair seamlessly integrates the mobility, gait training, and multiposture transformation. ReChair driving and multiposture transformation are done using the voice, button, and mobile terminal control. This work describes the functional requirements, mechanical structure, and control system and the overall evaluation of ReChair including the kinematic simulation of the multiposture transformation and passive lower limb rehabilitation training to quantitatively verify the motion capability of ReChair, the voice control system evaluation that shows how the voice recognition system is suitable for home environment, the sensorless speed detection test results that indicate how the wheel speeds measured by sensorless method are appropriate for travelling control, and the passive and balance training test results that show how the lower limb rehabilitation training in daily life by ReChair is convenient. Finally, the experimental results show that ReChair meets the patients’ requirements and has practical significance. It is cost-effective, easy to use, and supports multiple control modes to adapt to different rehabilitation phases.

Design and Preliminary Validation of a Lightweight Powered Exoskeleton During Level Walking for Persons With Paraplegia.

Upright-legged locomotion is a desirable ability for people with paraplegia. This paper introduces a newly developed lightweight powered exoskeleton (LIPE) for level walking and posture transfer of people with paraplegia using a user-centered design concept, which integrates the requirements of practical use, mechanical structure, and control system. The LIPE was evaluated with two subjects through several experimental tasks including kinematics and dynamics analysis in a local hospital. Results of functional evaluation showed that these subjects received the exoskeleton intervention well and the LIPE could provide appropriate gait assistance to the wearer during level walking, it could also help the wearer achieve the posture transfer from sitting to standing or from standing to sitting independently. Moreover, an endurance test also indicated that LIPE allows wearers to use it continuously for a long time. It is lightweight, cost effective, easy to use, and practical for people with paraplegia in their daily lives.

Polymer-Based Mechanochromic Composite Material Using Encapsulated Systems.

The development of mechanochromic or self-reporting polymers that can indicate damage or fatigue of materials with an optical signal has become of paramount interest to ensure the reliability of the materials and prevent catastrophic failure. This technology can potentially find usefulness for various applications, including in situ monitoring of mechanical events and structural health monitoring systems. An emerging and versatile approach to achieve mechanochromic properties relies on the encapsulation of dye solutions that can be released and activated (chemically or physically) when the walls of the capsules are mechanically damaged. While the mechanochromic effect can be achieved with different types of dyes and operating principles, this framework can also be designed with encapsulating-containers of different shapes and shell materials, such as microcapsules, hollow glass fibers, vascular networks, and micelles, making this concept applicable to a broad range of polymer matrices. An overview of the different encapsulation approaches that have been employed to prepare mechanochromic polymers is given, with a focus on the containers used for this purpose. A brief description of the containers' preparation is provided, and their associated chromic operating principles and progress in their designs are reviewed.

A Comparative Study on Vibration-Based Damage Identification and Localization Methods

This paper outlines various vibration-based methods for detecting and locating damage in mechanical and civil structural systems. The basic premises of these methods are that any changes in physical characteristics (mass and stiffness) of the structure will induce detectable changes in the modal properties of the structure (natural frequency, mode shape and damping). A comparative study of eight extensively used damage identification methods is done on a simulated simply supported beam to demonstrate the validity and effectiveness. The outcomes of various methods are compared in terms of damage detection and localization under single and multiple damage scenarios.

Development of contact displacement sensor based on frequency-modulated continuous-wave

Frequency-modulated continuous-wave(FMCW) interference measurement has the advantages of length traceability, large range, high precision, simple structure and optical fibre transmission. Based on the characteristics of the axial inductance sensor, a novel laser interference displacement sensor is developed. The formula of FMCW laser ranging is derived in detail and the mechanical structure and optical system of the contact displacement sensor are designed. Integrating the interferometric optical path into the sensor rod, converting non-contact measurement with cooperative targets into contact measurement can realize direct measurement of workpieces with complex surface conditions on the production line, such as free-form surfaces and oily surfaces. This technology expands the application of optical non-contact measurement. Experimental results show that the designed displacement sensor can reach a measuring range of 15 mm with a standard deviation of less than 0.01μm. It can meet the requirements of large-scale and high-precision inspection applications in the field of precision manufacturing.

Train probe for beam diagnostics of the SC200 superconducting cyclotron

The SC200 proton therapy system commissioned by the Hefei CAS Ion Medical and Technical Devices Co., Ltd. (HFCIM; Hefei, China) and the Joint Institute for Nuclear Research (JINR; Dubna, Russia) has made significant progress. A main radial beam diagnostic system (MRBDS) equipped with a new type of train probe was developed to satisfy the requirements of beam diagnosis. In this paper, the detailed design of the mechanical structure and electronics system of the MRBDS is presented. The electronics system, which includes hardware and software components, was tested and calibrated. The results show that measurement errors can be significantly reduced by the designed calibration procedures. The repeatability of the mechanical structure was also verified, and the experimental results indicate that the unidirectional repeatability of the positioning is better than 0.3 mm. Finally, the MRBDS was used to measure the phase lag of the particles in the beam, and the results showed a high degree of agreement with theoretical calculations, which proved the applicability and high efficiency of the MRBDS.

Voice controlled wheelchair integration rehabilitation training and posture transformation for people with lower limb motor dysfunction.

Stroke and other neurological disorders have an effect on mobility, which has a significant impact on independence and quality of life. The core rehabilitation requirements for patients with lower limb motor dysfunction are gait training, re-stand and mobility. A wheelchair called ReChair was invented that seamlessly integrated mobility, gait training and multi-posture transformation with voice control. The mechanical structure and control system of ReChair were designed. The overall evaluation included voice recognition and balance training test to quantitatively verify the performance of ReChair. The average success recognition rate of posture transformation by voice control can reach 91% to 96% in a quiet environment (20-30 DB). The balance training game is easy to operate and the score can be used as a quantified guideline for rehabilitation. The proposed rehabilitation wheelchair can realize multi-posture transformation and balance training by the voice control system.

Development of Rail Precision Cleaning Vehicle for Modern Tramway

Supported by the Zhuhai Collaborative Innovation Project, we develop a Road-Rail Precision Cleaning Vehicle for the rail of the first modern tramway based on the Tram Wave system in China, which has been built in Zhuhai City. Development scheme of overall mechanical structure, electrical control and condition monitoring system and man-machine interface system has been realized. We also designed a target recognition algorithm based on OpenCV to control actuators like solenoid valve, electromagnetic clutch and air pressure regulating valve and so on.

Exploiting spatial heterogeneity and response characterization in non-uniform architected materials inspired by slime mould growth

Inspired by shape-shifting features of slime mould growth, we implement a computational algorithm to study the nutrient-induced pattern formation and transition of slime mould. We then translate the learned principles into the design and characterization of cellular materials, with particular focus on the issue of spatial heterogeneity due to the nature of the non-uniform, asymmetric pattern. Guided by clustering analysis, compression tests on 3D-printed samples, and numerical simulations by finite element models, we were able to categorize patterns with certain geometric features (such as layout and symmetry) and found similar mechanical response features, indicating high tailorability of non-uniform architected materials. This study paves the road for the advanced computer-aided design of architected materials and its potential in the development of innovative engineering mechanical devices and structural systems.

Design and Isokinetic Training Control Method of Leg Press Training Device

Lower-limb function in elderly people gradually degenerates with age, and poor rehabilitation conditions preventing the elderly from receiving scientific rehabilitation training result in the decline of social labor force and the increased economic burden of the elderly. Aiming at the characteristics of the single function and the complex structure of an existing telescopic leg trainer combined with the needs of the application group, a new type of leg-stretching training device with multiple training modes for lower extremity extension and flexion of the elderly is proposed. A new mechanical structure and electrical system is designed. At the same time, the anti-resistance training man–machine model is analyzed, aiming at the isokinetic resistance training mode, and a training controller strategy based on a fuzzy synovial algorithm is proposed. Finally, the feasibility of the designed controller strategy and the proposed leg training device are verified by prototype experiments, which will guide further research.

Observer-based feedback linearization control of multi-input multi-output nonlinear system and application to double rotor system

This study first proposes an observer-based feedback linearization control of nonlinear multi-input multi-output systems with the input-to-state stability and almost disturbance decoupling characteristics, and summarizes an efficient algorithm for deriving the almost disturbance decoupling control. The state variables for the nonlinear dynamic equations generally are not available, and a state observer is applied to estimate the state variables. The existing approach solves the almost disturbance decoupling problem under the difficult sufficient conditions including the nonlinearities which are not globally Lipschitz and disturbances which appears linearly but multiplied nonlinearities. On the contrary, this problem can be easily solved via the proposed approach without those difficult conditions in this study. The generality of this approach and implications, due to the fact that unlike Jacobian linearization feedback linearization is not only locally valid, are also shown. The double rotor multi-input multi-output system mechanical structure is a laboratory equipment for some flying viewpoints and is investigated in this study to demonstrate the practical value of the proposed results.

Integral Fuzzy Sliding Mode Impedance Control of an Upper Extremity Rehabilitation Robot Using Time Delay Estimation

Robot-assisted cooperative rehabilitation training has shown superiority in helping the individuals with motion impairment problems to regain their motor functions. This paper presents the development and evaluation of a new cooperative training control scheme for an end-effector-type rehabilitation robot to provide upper extremity rehabilitation training with desired compliance and intensity. Firstly, the overall mechanical structure and real-time control system of rehabilitation robot are introduced. Secondly, an integral fuzzy sliding mode impedance control strategy combined with time-delay estimation (IFSMIC-TDE) is proposed to induce the active participation of patients and suppress impedance error. The IFSMIC-TDE approach is free from nonlinear robot dynamics, and it is designed to be robust to the external uncertainties and inherent chattering characteristics. After that, the closed-loop system stability with IFSMIC-TDE is proved based on the Lyapunov stability theory. Finally, experimental investigations are conducted to illustrate the effectiveness of the proposed rehabilitation robot and control algorithm. The comparison results indicate that the proposed IFSMIC-TDE can achieve better control performance and less impedance error. Besides, the interaction compliance and training intensity can be qualitatively adjusted via appropriate impedance parameters.

A high-throughput system for automated bottle mouth defects inspection

Bottle mouth defects inspection is very important for the production line of beverage and medicine. In this paper, an intelligent inspection system for bottle mouth defects is presented. The linear convection mechanical structure and electrical control system based on industrial personal computer (IPC), motion card and data I/O card are firstly illustrated in detail. Thereafter, a method using the high-speed camera is applied to obtain the bottle mouth image. To find the centre of bottle mouth, a novel multi-search-orientation algorithm is proposed, and then the differential detection method based on ring scanning tangent is used to identify the cracks of the bottle mouth. The experimental results show that the detection algorithm is effective and the system is reliable.

Design and Development of a Portable Exoskeleton for Hand Rehabilitation.

Improvement in hand function to promote functional recovery is one of the major goals of stroke rehabilitation. This paper introduces a newly developed exoskeleton for hand rehabilitation with a user-centered design concept, which integrates the requirements of practical use, mechanical structure, and control system. The paper also evaluated the function with two prototypes in a local hospital. Results of functional evaluation showed that significant improvements were found in ARAT (P = 0.014), WMFT (P = 0.020), and FMA_WH (P = 0.021). Increase in the mean values of FMA_SE was observed but without significant difference (P = 0.071). The improvement in ARAT score reflects the motor recovery in hand and finger functions. The increased FMA scores suggest there is a motor improvement in the whole upper limb, and especially in the hand after the training. The product met patients' requirements and has practical significance. It is portable, cost-effective, easy to use and supports multiple control modes to adapt to different rehabilitation phases.

Microcapsule-Containing Self-Reporting Polymers.

Self-reporting polymers, which can indicate damage or exposure to excessive stress with a clearly perceptible optical signal, are potentially useful for several technological applications, including stress-sensitive sensors that enable in situ monitoring of mechanical events and structural health monitoring systems. A versatile and simple concept to realize this function is the exploitation of microcapsules that are filled with solutions of dyes that are released and chemically or physically activated when the protective shell is damaged. Such microcapsules can readily be incorporated into polymers and the composites thus made can be processed into films, coatings, or other objects. Mechanochromic effects can be realized with different types of dyes and activation schemes. In this concept article, a selection of recent key studies is presented to provide an overview of the state of the field. Different architectures and operating principles and their advantages and drawbacks are reviewed. The parameters that influence the design of microcapsule-based mechanochromic systems are considered and unexplored chromophore systems that might be useful to design future self-reporting polymers are discussed. Finally, specific aspects of capsule design, fabrication, and integration into polymers are presented. Throughout the article, challenges and opportunities of the concept are highlighted and possible future directions are discussed.

Development of an RBFN-based neural-fuzzy adaptive control strategy for an upper limb rehabilitation exoskeleton

The patients of paralysis with motion impairment problems require extensive rehabilitation programs to regain motor functions. The great labor intensity and limited therapeutic effect of traditional human-based manual treatment have recently boosted the development of robot-assisted rehabilitation therapy. In the present work, a neural-fuzzy adaptive controller (NFAC) based on radial basis function network (RBFN) is developed for a rehabilitation exoskeleton to provide human arm movement assistance. A comprehensive overview is presented to describe the mechanical structure and electrical real-time control system of the therapeutic robot, which provides seven actuated degrees of freedom (DOFs) and achieves natural ranges of upper extremity movement. For the purpose of supporting the disable patients to perform repetitive passive rehabilitation training, the RBFN-based NFAC algorithm is proposed to guarantee trajectory tracking accuracy with parametric uncertainties and environmental disturbances. The stability of the proposed control scheme is demonstrated through Lyapunov stability theory. Further experimental investigation, involving the position tracking experiment and the frequency response experiment, are conducted to compare the control performance of the proposed method to those of cascaded proportional-integral-derivative controller (CPID) and fuzzy sliding mode controller (FSMC). The comparison results indicate that the proposed RBFN-based NFAC algorithm is capable of obtaining lower position tracking error and better frequency response characteristic.