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 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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.
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.
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.
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.
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.