To improve the rate of broken rice in a rice mill machine, experiment and simulation work of the rice milling process was employed. Results showed that the increasing sieve edges caused a decreasing compressive force and increasing milling time, resulting in the maximum rate of broken rice and milling degree in the octagonal sieve. The uniformity of the milling process could also be optimized by adjusting the geometries and numbers of the convex ribs of the rotating roller.
This paper proposes a bionic, multi-posture wheelchair, based on the proposed human–wheelchair coupling model, according to the movement characteristics and requirements. The two key factors in designing the multi-posture wheelchair, the consistency of the motion center and the compensation of the shifting center of gravity, are analyzed in this paper. The novel multi-posture wheelchair can implement the sit-to-lie and sit-to-stand transformations with a maximum slipping distance of 10.5 mm.
It is more efficient and safe to use a sub robot to replace the mother robot to perform space exploration tasks full of challenges. A novel three-rocker-arm six-wheeled robot with adaptive obstacle-crossing capability was designed to form a sub-parent exploration system with a large robot and to perform exploration tasks. A prototype of the robot is developed, and the experiment results show that the robot can maintain stability in rugged terrain and has excellent ability to cross obstacles.
In this paper, we use the folded section hypothesis to determinate the ratchet tooth root bending stress and provide a normal mathematical model to calculate it. This model has been proved by the finite element analysis method and the ratchet experiment. It is recommended that this model be used to predict the ratchet tooth root bending stress in the ratchet design process.
In order to solve the problem of the nonlinear frequency response of a planetary gear transmission system, based on the lumped parameter theory, a nonlinear frequency response model with a bending torsion coupling of a planetary gear system is established by comprehensively considering the backlash, support clearance, time-varying meshing stiffness, static transmission error, external periodic excitation and other factors.
The influence of wind load on the vibration of ultra-high-speed elevator can no longer be disregarded, and the maximum horizontal vibration acceleration of the guide rail is positively correlated with the height of the building. In addition, the vibration acceleration of the same height rail increases with the increase in wind pressure. This study provides important guidance for researchers studying the horizontal vibration response of ultra-high-speed elevators.
This paper designs a type of bionic-gibbon robot with three links and two grippers. We apply the sliding-mode control to the swing motion of the robot. The bionic-gibbon robot can complete continuous brachiation motion on the irregularly distributed bars. Besides, compared with the two-link structure, the three-link structure introduced in this paper improves the swing efficiency and increases the swing height of the robot.
In the early stage of the creative design of mechanisms, design work was accomplished mainly based on researchers' experience and inspiration, resulting in a low design efficiency. Moreover, the derived mechanism configurations were very limited. An effective mechanism design method is based on the atlas of topological structures of kinematic chains. Our research on the structural synthesis of kinematic chain inversions plays an important role in the improvement of mechanism design efficiency.
This study is focused on analyzing signal changes according to internal flow and temperature change by generating micro-leakage, unlike previous studies that experimented with no flow inside a chamber. In addition, a new application method utilizing a phase shift by post-processing the ultrasonic reception signal was proposed. By using the ultrasonic sensor, a different method was proposed for the measurement of micro-leakage of gaseous fuel that relied on the existing pressure sensor.
This paper presents the force analysis and optimization of four versions of self-adaptive robotic fingers based on the simplest closed-loop 1 degree-of-freedom mechanism possible, namely the four-bar linkage. Two of these versions include prismatic joints. It was concluded that simpler designs in adaptive fingers do not necessarily mean weaker performances since the results are at least comparable with other designs with more degrees of freedom.
The electrically driven Stewart platform (EDSP) is used widely. However, the passive rotation (PR) on driven branch chains can generate posture error on the end effector. Compensation control strategy is designed to avoid effects of PR on posture accuracy of the 6-DOF (degrees of freedom) EDSP based on calculation and analysis. The validity of analysis and the effectiveness of the compensation method used to improving posture accuracy are proven by simulation and experiments on a 6-DOF EDSP.
To solve the kinematics mapping problem for the joint space and the drive space of a hyper-redundant manipulator based on flexible cable actuation, which is the key for hyper-redundant manipulators to move strictly according to trajectory planning and avoid obstacles, a decoupling method for kinematics analyses of the flexible cable actuation space and the joint rotation space was proposed.
Small motor stator winding at the same time is difficult to guarantee the uniform arrangement of enameled wire. This paper proposes a three-phase parallel equivalent multi-wire winding robot. The manipulator structure is designed, and the joint motion planning simulation is carried out to verify the feasibility of the multi-wire parallel winding hybrid robot. The research results of this paper provide a theoretical reference for multi-wire parallel winding equipment control.
This paper investigates planetary gear reducers with double satellite gears. These reducers are present in present-day industrial robots, electric vehicles, etc. The paper deals with the dynamic behavior of the reducer as a whole system. The acceleration, velocities, and movements are solved for all elements based on the defined dynamic model. For a dynamic model definition, we used Lagrangian equations of the second kind. The results can be used in design, investigation, etc.
Based on the freedom and constraint topology approach and atlas approach, a new method for the synthesis of a redundant actuated compliant parallel mechanism is proposed, the synthesis conditions are given, and the synthesis process is formulated. With this proposed method, two new translation redundant actuated compliant parallel mechanisms are synthesized, and some new mechanisms have been synthesized. The degree of freedom analysis verifies the correctness and effectiveness of the method.
The new pneumatic–electric hybrid actuator with pneumatic and electric driving modes has the problem of speed fluctuation in the process of driving switching. This affects the stability in the positioning process. In order to solve this problem, the motion characteristics of piston rod in pneumatic locking are studied. A relay and run strategy is proposed to solve the problem of speed fluctuation.
This article contains new propositions for modelling piezoelectric stack models by using existing classical and non-classical methods with the aim of improving piezoelectric stack capabilities. Polynomial chain fractioning is used to obtain a mechanical model with a cascade structure. To verify model output frequencies and amplitudes, edge graphs and structural numbers are used. With the help of Kelvin–Voigt, Mason and Maxwell slip models, an electromechanical model solutions are proposed.
A universal test-machine-based mechanically driven friction device was designed and manufactured. Friction tests were conducted on a third-generation high-strength steel QP980 with flat and curved dies at different pulling speeds and clamping forces. The formula for calculating the friction coefficients between curved contact surfaces was derived.