The study provides contributions to motion control systems with friction, especially for micro-motion systems. Five most used friction models in the micro-motion systems were compared. The plausible reasons for the difference in performance among these models applied in micro stick-slip motion were discussed.
This study also demonstrates an idea of using displacement measurement of micro motion system and system identification technique to investigate the dynamic friction in micro motion level.
A systematic method was proposed for the synthesis and creative design of novel structures that can be used to build wheeled mobile robot. The proposed method has led to 236 new design schemes. Mathematical models and a software platform were developed to provide appropriate and intuitive tools for simulating and evaluating performance of the wheeled robots. Physical prototypes of sample wheeled robots were developed and tested, proving and validating the principle and methodology presented.
This article proposes a novel monolithic compliant spatial parallel XY stage (SPXYS). An important feature of the SPXYS lies in that it can deliver centimeter travel range and sustain large out-of-plane payload while possessing a compact structure, which makes the SPXYS suitable for some special applications such as Ultra-Violet Nanoimprint Lithography and soft-contact lithography.
Origami is a powerful and elegant tool that can be used by engineers to overcome challenges. The shape of the origami is essential to this. We categorize the shapes (fold states) of origami into seven classifications. This categorization method is supported by analyzing 69 origami-based devices for correlations between the classification and the types of functions they perform. These correlations can be used to design and select origami fold states.
Hidden-keyhole padlocks are reconfigurable mechanisms and a category of ancient Chinese locks. This work presents a useful procedure to indicate and analyze the topology variabilities of hidden-keyhole padlocks. The variable chains of hidden-keyhole padlocks are presented by using the representation of kinematic pairs, from which all topology variabilities of padlocks in the operation are derived. Four main types of hidden-keyhole padlocks are provided as examples to illustrate the procedure.
The traditional concepts on severe accident mitigation weren't seriously challenged until the occurrence of Fukushima accident on 2011, suggesting the structural behavior had not been appropriately assessed. Therefore, the paper tries to address the structure-related issue on determining whether structural safety can be maintained or not with the effect of various water levels and internal pressures created from core meltdown accident. The creep and plastic damages are interacted with each other
This study proposes a worm gear efficiency model considering misalignment in electric power steering systems. Geometrical and tribological analyses were performed and in order for validation of the model, a worm gear was prepared and the efficiency of the worm gear was predicted by the model. As the final procedure of the study, a worm gear efficiency measurement system was set and the efficiency of the worm gear was measured and the results were compared with the predicted result.
The spherical flexible joint is used to connect the Tension Leg Platform to the seabed. It can provide low shear stiffness while bearing high compression force. So the research on the stiffness of flexible joint is necessary. The linear rotational stiffness of the flexible joint is formulated and FEM is used to verify the analytical solution. The increase of Poisson's ratio of the rubber layers will enhance the vertical compression stiffness but barely have effect on the rotational stiffness.
A continuous static gait of a quadruped robot benefited from the twisting trunk performing the increased stride length is introduced. After that, the increased stride length relative to the trunk twisting will be analysed mathematically. Other points impacting the implementation of the increased stride length in the gait are investigated such as the upper limit of the stride length and the kinematic margin. The increased stride length in the gait will lead the increase of locomotion speed.
Due to the time-consuming and inefficient traditional tool selection method based on the human experience, we apply transfer learning to CNC tool selection issue in the field of industrial manufacturing. A unified expression of expert experience and process case is given in a more complex environment and then we improve the algorithm. The results show that the method we proposed can facilitate tool selection.
An automatic, non-contact measuring system for the thread profile of a ball screw was developed. It is capable of measuring most common features of the ball screw thread profile and can measure ball screws of different sizes and lengths. The accuracy of the measuring system was verified by comparing the image from the system with the image from the reference instrument and then, different ball screws were compared and evaluated, which was the main purpose of designing such a measuring system.
The research into micro machining of advanced alloys finds its applications in the aerospace, automotive, biomedical and healthcare and other industrial areas. One of the major concern is to produce parts at micro level without further rework, specifically surface finish. In order to achieve this, suitable process parameters and machining strategy needs to be identified for advanced alloy. The research presented here focuses on this aspect of the machining of Titanium Alloy.
This article presents a novel continuum robot actuated by two extendable balloons. As inflated, the balloons apply a force on the wall of the tip, pushing the robot forward. The contribution of this study is the introduction of a novel actuation mechanism for soft robots to have extreme elongation (2000 %) in order to be navigated in substantially long and narrow environments.
It is proposed a novel design method for large stroke XY compliant mechanisms. An important feature of the design lies in it restricts the parasitic rotation by reducing the moment of force instead of increasing the rotational stiffness widely utilized in the literature. It is presented a millimeter stroke XY nanomanipulator with the proposed design based redundant constraint in a case study. The proposed design provides an alternative to reduce the parasitic rotation of XY compliant mechanism.
The aim of this study is to integrate suggested control algorithms with a mechatronic design of underactuated adjustable stiffness finger for improving grasping operation. The designed robot finger system has the following main features: (1) preventing damage of objects during contact with phalanges, (2) having firm grasping, (3) adjusting grasped-forces on phalanges by stiffness of joints, and (4) implementing job independently without external control unit.
This paper presents a new exoskeleton design for wrist and forearm rehabilitation. The contribution of this study is to offer a methodology which shows how to adapt a serial manipulator that reduces the number of actuators used in exoskeleton design for the rehabilitation. The system offered is a combination of end-effector- and exoskeleton-based devices. The passive exoskeleton is attached to the end effector of the manipulator, which provides motion for the purpose of rehabilitation process.
In this paper, a numerical model for the analysis of bond-slip occurring in concrete filled steel tube (CFT) columns is introduced. The introduced model considers the bond-slip effect by incorporation of the equivalent steel stiffness. Finally, the validity of the introduced numerical model is verified by comparing the experimental data with the analytical results for CFT columns subjected to axial force and bending moment.
The mechanical behaviour of a creased thin strip under opposite-sense bending was investigated，revealing that a simple crease could significantly alter the overall mechanical behaviour of a thin strip. The influence of the geometrical parameters on the mechanical behaviour of the creased strip was studied. The deformation patterns of the thin strips from the finite element simulations were verified by physical models made from thin metal strips.
Analytical and numerical analyses have been performed to study the problem of magneto-hydrodynamic (MHD) flow and heat transfer of an upper-convected Maxwell fluid in a parallel plate channel. The Homotopy Analysis Method (HAM), Homotopy Perturbation Method (HPM) and fourth-order Runge-Kutta numerical method (NUM) are used to solve this problem. Also, velocity and temperature fields have been computed and shown graphically for various values of the important physical parameters.
In rehabilitation, the widely existing misalignment between human limb and exoskeleton causes discomfort even danger. To alleviate the misalignment in lower extremity exoskeleton, this study proposes a compliant parallel mechanism, which has the potential to automatically change its configuration to make exoskeleton knee joint fit the human joint movements. And the self-alignment performance of the mechanism is validated via conducting a series of experiments under different working conditions.
The Beam Constraint Model (BCM) may yield large predicting errors (> 5 %) when the applied axial force goes beyond a certain boundary. We mathematically determine the nondimensional boundary of the axial force by the conditions of the positive definite quadratic form of the strain energy expression and the buckling load expressions. If the axial force is beyond the boundary, the Chained Beam Constraint Model (CBCM) can be used instead.
In order to improve the uniformity of workpiece allowance distribution, a stepwise workpiece matching adjustment method with contact inspection is developed.The stepwise matching includes the rough and fine matching processes. After matching, the spatial transformation matrixes R, T and the adjustment values of machine tool can be obtained accurately. At last, some experiments were presented to demonstrate the performance of the method.
In this study, a compliant wiper mechanism is presented which can be used in land, air, and sea vehicles, particularly the automotive industry. The wiper mechanism is essentially a partially compliant four-bar mechanism. To the best of our knowledge, this is the first compliant wiper mechanism in the literature. After the theoretical calculations, a prototype is manufactured and an experiment is set up. The data obtained from the experimental setup are compared with the theoretical results.
The aim of this study is finding a modified lapping method to improve the lapping effect, increase efficiency and change the present labor-intensive situation. In this study, a modified lapping tool was designed and it was designed to fit on a specially designed friction torque test machine. In addition, a set of orthogonal experiments were designed to capture the effects of four main lapping factors: friction torque, abrasive particulate size, lapping time and the rotational speed.
The conceptual design of balance shaft was very important process as how to locate the unbalance masses and corresponding supporting bearings. In this paper, the optimal conceptual balance shaft model was derived by using proposed objective functions for an inline 3-cylinder engine and an inline 4-cylinder one, respectively. Two kinds of optimal model were derived from simulations and efficient design guidelines was finally explained with design flowchart.
In this paper the potentiality of using Pa2 joints for designing robots with parallel structure and translational motion is studied. As the equations governing its motion are simpler than those of other structures, the control system of the robot is more efficient and reliable. The structure proposed has high stiffness improving the accuracy of its movements.
A new exoskeleton for human gait motion assistance and rehabilitation is proposed, to investigate motion capabilities and feasibility. Human gait analysis on healthy and disabled subjects is performed to obtain references motion laws for normal gait. A dynamic simulation model of exoskeleton is achieved in ADAMS computational environment. The exoskeleton prototype motion laws, resulted from motion analysis based on ultra speed video cameras are compared with human subject motion laws.
The offset panel technique (OPT) is a method which accommodates for the use of thick materials in origami models and preserves both the range of motion and the kinematics. This work explores new possibilities for origami-based product applications presented by the OPT. Examples are included to illustrate some of the capabilities of the OPT, including the use of various materials in a design and manipulation of panel geometry resulting in increased stiffness and strength in the design.
Elastic systems that undergo large deformations are difficult to analyse because, while deforming, their mechanical properties change nonlinearly, which makes it difficult for designers to use them.
In this work we make use of a graphical representation of the mechanical behaviour of a selected elastic object, a spiral spring, to facilitate the understanding of its behaviour. The use of these graphs is illustrated by generating peculiar examples of systems with many stable configurations.