In this paper, an effective UKF-based estimation method is proposed to accurately estimate the driving states of vehicles. First, a three degrees of freedom (3-DOFs) vehicle dynamics model is established, and then a vehicle driving state estimation method is designed based on the UKF algorithm. Finally, by using CarSim and MATLAB/Simulink software, the co-simulation and validation are carried out to validate the accuracy of the proposed method under the sinusoidal and fishhook conditions.
This study carries out the complex eigenvalue analysis of influence factors of rail corrugation by using the three-dimensional finite-element model of a wheel–rail system based on the theory of friction self-excited vibration. The results show that improving the vertical and lateral stiffnesses of fasteners, controlling the wheel–rail friction coefficient below 0.4, and maintaining balanced superelevation can effectively reduce the occurrence possibility of rail corrugation.
The paper proposed a normal contact stiffness model considering 3D topography and elastic–plastic contact of rough surfaces. The proposed model is validated using experimental tests conducted on two types of specimens and is compared with published theoretical models. The proposed model can provide a tool for efficient calculation of the contact force, deformation, and contact stiffness in engineering surfaces.
Non-circular grinding is used in the grinding of crankshafts. In this study, an equation for detecting the angle error in non-circular grinding is established. Previous studies did not exclusively detect the errors caused by bending deformation and torsional deformation. However, the established equation detects these errors separately. The angle error was found to be up to 0.44 arcsec, which is 5 % of the angle error obtained from previous studies.
A program is designed for the myoelectric hand with two control pathways, one for the thumb (controlled utilizing medial nerves) and the second for the rest of the fingers (controlled by the side nerves). The robotic hand was first printed with the use of a 3D printer.
The temperature distribution of a machine tool spindle is affected by its air gap. The more serious the air gap eccentricity is, the more uneven the temperature field of the spindle is. In the process of machine tool processing, the instability of the spindle temperature field leads to the decline of parts processing quality and unqualified products, which not only wastes materials, but also affects the processing process.
In this paper, a lined pipe was formed through a drawing process. In double-layered pipes, shear strength is the most important design factor. We verified the effect on shear strength by changing the pipe surface roughness. In order to apply the surface roughness in FEM analysis, the surface roughness was converted to the friction coefficient. Through FEM analysis, we obtained a critical value for the change in shear strength.
In order to improve modification effectiveness, a novel UV-assisted chemical modification (UVA-CM) strategy is proposed based on UV photocatalytic theory, which contributes to developing a novel hybrid chemo-mechanical process monocrystalline silicon. A series of comparative experiments was performed to evaluate modification effectiveness among different strategies. The results show that the liquid–solid chemical modification effect is obviously enhanced through UV advanced oxidation reactions.
Liquid-metal direct writing is a cost-effective and green technology, which is very promising for the customized fabrication of flexible circuits and functional devices. The smooth flowing and conveying of liquid-metal ink are still huge challenges that need significant attention. In this paper, the force mechanism of liquid-metal ink transported by ball rotation and translation of the printing head was analyzed. The flexible complex circuit and functional electronic pattern were printed.
This paper describes a dynamic mathematical model of a new type of two-stage nutation drive system with double circular-arc bevel gears. The dynamic displacement-vibration coupling model takes into account the gyro torque and side clearance of the nutating gear. A numerical analysis geometric model of the nutation drive system is developed. The geometric model considers the time-varying and contact deformation of nutation gear meshing.
This article examines the historical development of ancient water-powered mechanical clocks. The study begins with a comprehensive analysis and comparison of the different types of ancient clepsydra, their use and development, development of their feedback systems, power systems, and time-reporting systems.
According to the structural characteristics of the blisk, a new adaptive belt tool system for the blisk finishing is developed. Due to the strong nonlinearity of the pneumatic system, a two-dimensional fuzzy PID controller is developed for the pneumatic force control. Finally, the experiments show that the polishing process is very stable and the roughness after polishing is less than 0.4 μm, which proves the effectiveness of the proposed new belt tool system and the fuzzy PID controller.
Robots are a hot topic of research nowadays. Making robot action more accurate and faster is the direction of scholars' efforts. Based on the hydraulic quadruped robot designed by the State Key Laboratory of Fluid Power & Mechatronic System, Zhejiang University, this article discusses the lightweight design for manifold mounted on the hydraulic actuator. Through topology optimization and channel optimization, the part is lighter and the drag loss is less.
This paper presents the design of a dynamometer, with a one-spoked wheel elastic component, to measure the drilling thrust force and drilling moment. After manufacturing, a calibration operation is conducted, and tests are performed by measuring the drilling forces, thrust, and torque on American Iron and Steel Institute (AISI) 1020 steel. Tool wear is studied, and the results are presented in the paper. Obtained results demonstrate the efficiency and accuracy of this measuring instrument.
In this article, the lightweight design of a palletizing manipulator arm structure is carried out. The optimization target is designed in 3D with Solid Works. To determine the optimization area and the secondary reconstruction model after the structure is optimized, the reliability and cost of the design structure are also considered. The meta-software performs mechanical performance simulation experiments under the corresponding working conditions for the lightweight structural design.
1. A new type of MRE torsional vibration absorber (TVA) is devised. The modal analysis, the frequency tracking scheme, and the damping effect are intensely studied. 2. A transient dynamic simulation is carried out to validate the rationality of the machine structure. The magnetic circuit simulation analysis and the magnetic field supply analysis are performed to substantiate the intellectual of the TVA. 3. A special test rig is built to assess the frequency shift characteristics of the TVA.
In industrial production, the reducer often determines the accuracy of the machine. Designing a reducer with high strength and good accuracy plays an important role in industrial development. In this paper, combined with previous studies, a new type of reducer based on the lever structure is designed, and the performance of the reducer is optimized. Finally, the most appropriate geometric parameters are obtained to ensure the high efficiency of the reducer. It is effective and stable.
We discuss a systematic electric vehicle design process. The steering geometry of the vehicle is analyzed, and the turning angle and radius are designed. The displacement of the vehicle under a load is calculated by rigidity analysis. The experimental modal analysis of the real frame and the finite element method are verified for the body-in-white manufacturing process. No-fuse switches and fuses are used to provide overcurrent protection. A solid-state relay is used for current protection.
A nonlinear dynamic model of the noncircular face gear (NFG) was established. A semi-analytical approach, based on HBM and discrete Fourier transformation, is utilized to obtain the periodic responses. The results show that an increase in the eccentric ratio, input velocity and error amplitude will cause the non-rattle, unilateral rattle and bilateral rattle state in succession, and a jump phenomenon will appear when the state of the gears is transformed from unilateral to bilateral rattle.
This paper proposes a novel geometrical approach to compliant mechanism synthesis based on similarity transformation of pole maps. The study demonstrates the feasibility of applying the geometric similarity transformation to the compliant mechanism and then proposes the procedure of synthesis method. In addition, this work illustrates the synthesis method with two examples.
This paper introduces several types of multi-engine multi-gearbox marine gearing. A total of two dynamic modeling methods are proposed to predict the coupled vibration of these systems. The dynamic models of four engines with two shafts under different working conditions are established, and the effects of coupling, speed, configuration and power loss on the system vibration are studied.
A wave energy converter has been investigated, which can convert the absorbed wave energy into electrical energy. Through electromagnetic numerical simulations, the influences of linear generator parameters such as magnetization mode, air gap, and yoke shape on electromagnetic performance were evaluated. Numerical results show axial magnetization and Halbach magnet array can increase magnetic flux intensity more than the radial mode. The conversion rate of wave energy is derived.
This paper reviews the state-of-the-art trajectory tracking of autonomous vehicles. Autonomous vehicles have become more and more popular with the development of artificial intelligence and automatic control. If you have any interest in the trajectory tracking of autonomous vehicles, this paper is the one that you can not miss. It will give you a brief concept of the current development of the trajectory tracking of autonomous vehicles.
To improve the control accuracy, dynamic and static characteristics of the system need to be tuned. In this paper, we use a glowworm algorithm with an improved adaptive step size to tune the parameters of a robust adaptive fuzzy controller. Finally, the workpieces of three different materials are cut with two different cutting methods. The study revealed that the surface roughness value is reduced by 20 %–32 %, which further verifies the effectiveness of the optimal controller’s parameters.
A method is developed for planar four-bar linkages to cope with the mixed synthesis of motion and path-generation problems. The developed method selects an optimal combination by using the conic filtering algorithm, which is based on the similar characteristics of the value and direction between the conic and coupler curves in a certain neighborhood. The selected combination is substituted into an equation system of motion synthesis to solve the parameters of the planar four-bar linkages.
This paper presents an industrial robot-aided ultrasonic thickness measurement system to meet the needs of precise and efficient wall thickness measurement of large thin-walled parts. The hardware platform of the system is established with the designed reliable and contactless ultrasonic device integrated into an industrial robot. It was experimentally proven that the proposed method has a positive significance for improving the accuracy and efficiency of thickness measurement.
This investigation is a further study on the consideration of the cutting edge radius of the cutter and the material of the workpiece based on the methods of finite element simulation and the micro end cutting experiment. The minimum undeformed chip thickness (MUCT) value increases with the increase of the cutting edge radius, no matter which process. In this study, the influence of important variables on MUCT is studied as much as possible to reflect a real application situation.
In this paper, a high-rigidity screw-type tip-inserting mechanism with a good centering effect is designed. The structural characteristics and working principle of the inserting mechanism are introduced, the stiffness model of the new-type pipetting device is established and its stiffness and axial deformation are calculated. Finally, a multi-station high-throughput automatic pipette produced by a company was used as an example to optimize and improve it and conduct a prototype test.
The center-point steering theory of a traditional tracked vehicle cannot be directly applied to a tracked omni-robot. In this study, for the three typical layout types, rectangular, hybrid, and centripetal, the steady center-point steering motion of a tracked omni-vehicle under skid conditions is analyzed and a correction model is investigated. The correction model can correct the angular velocity and time of the vehicle, as well as give the relationship between the design parameters.
This study performs an analytical study of the modal and natural frequencies and the vibration types of each order of the gearbox housing structure of a planetary gear reducer (PGR). An optimal housing structure for a PGR with lower acoustic vibrations is designed, and a composite housing structure with damping vibration attenuation and acoustic absorption is proposed. The radiation acoustic characteristics without acoustic protection and damping materials are analyzed.
An analytical method for programming piston displacements for constant flow rate piston pumps is presented. The results show that, with the given transition functions, cam profiles can be designed analytically with parameterized forms, and the maximum accelerations of the pistons are determined by the width of the transition domain and the rotational velocities of the cams, which will affect contact forces between cams and followers.
The dynamic load-sharing characteristics of a face gear dual-power split transmission system (FGDPSTS) of an aircraft helicopter are studied. The effects of error, backlash, support clearance, spline clearance, torsional stiffness and support stiffness on dynamic load-sharing performance are analyzed. The load-sharing coefficient increases with the increase of the error, which provides a theoretical basis for the dynamic stability optimization design of the system.
Compared with the hydrostatic CVT used in the current cotton picker, the hydrostatic power split CVT has lower energy and fuel consumption. However, this kind of transmission usually has multiple speed regulation ranges, and the adjacent two ranges will produce impact and affect the driving comfort when shifting. In this study, the shift process of a hydrostatic power split CVT was analysed, and the results prove the feasibility of the application of this kind of CVT in the cotton picker.
An innovative flapping wing micro aerial vehicle (FWMAV), forming a figure eight wingtip trajectory, which can achieve complex composite motions of flapping, twisting, and swinging is presented in this paper. Along with the design concept of reducing any possible weight and size, the aircraft was designed with classical and reliable mechanical components. Then, experiments were conducted to test the FWMAV aerodynamic efficiency with a complex figure eight wingtip trajectory.
The deformation of blades under complex loads of multiple working conditions reduces the energy conversion efficiency. To reduce the deviation of the blade shape in practical working conditions, a combination and optimization method of blade design schemes under multiple working conditions, based on the entropy weight vague sets, is proposed. The results show that the proposed design scheme has a smaller blade shape deviation than the traditional design scheme under multiple working conditions.
Rotary forging with double symmetry rolls (DSRs) is a new metal plastic forming technology developed on the basis of conventional rotary forging with a single roll, which uses a pair of symmetrical cone rolls to realize continuous local pressure plastic deformation of the workpiece. Compared with the conventional rotary forging with a single roll, it has many outstanding advantages. Rotary forging with DSRs can form large diameter : thickness ratio discs.
This paper proposes a novel, 4 degrees of freedom, end-effector-based upper limb rehabilitation robot with space training. The robot can assist the human upper limb in performing rehabilitation training of the shoulder flexion/extension and adduction/abduction and elbow flexion/extension. Different from the desktop-type end-effector-based robot, the proposed robot can provide a wide range of shoulder flexion/extension training and cover the range of movement of the human upper limb.
This paper proposes a new 13 degrees of freedom equivalent kinematic model for the human upper limb and fully considers the movement characteristics of human upper limbs in anatomy. The proposed model can be utilized to analyze the human upper limb workspace and joint motions. Furthermore, the model can effectively evaluate the existing upper limb exoskeleton and provide suggestions for structural improvements in line with human motion.
This paper investigates the influence of friction effects on a gear-rotor system in compressed air energy storage (CAES), a new mathematical model of the system is established, and some new vibration characteristics of the gear-rotor system are shown in this paper. The results obtained in this paper will provide a reference for the study and design of a gear-rotor system in CAES.
In this paper, the fractional model of the asynchronous motor rotor was firstly established with a peculiar memory characteristic, and the introduced harmonic response was able to fit the reality well. Then, we set high rigidity and less mass as optimization functions and transform them into the problem of the first-order frequency and mass. In order to find the optimal parameters, an accelerated optimization method based on response surface is proposed.