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Aiming at the unbalancing problem of the neutral equilibrium characteristic for balance hoist in the loading process, the purpose of this paper is to establish a dynamic equation for multi-body using the Lagrange method. It is not difficult to find that the deformation of the boom system has a great influence on the stability of the whole system, through the simulation analysis of the multi-rigid-body system model.

Aiming at the unbalancing problem of the neutral equilibrium characteristic for balance hoist in the loading process, the dynamic equation for multi-body is established by Lagrange method. It is not difficult to find that the deformation of the boom system has a great influence on the stability of the whole system, through the simulation analysis of the multi-rigid-body system model.

Result shows that different weights have a great influence on the force deformation and vibration of the boom system of balance hoist. With the increase in lifting weight, the force and deformation of the boom system increase; lead to balance hoist unique with characteristics of indifferent equilibrium, proportional amplification, labor-saving operation will be lost, easy to cause the imbalance of balance hoist. Therefore, the appropriate increase in the basic length of the compression bar, reduction in the basic length of the tension rod and the increase stiffness of the boom system can improve the stability of balance hoist, which provides a reference for the optimization and manufacture of the balance hoist structure.

The simulation model was established by analyzing the working principle and the load condition of the balance hoist, and the simulation and dynamic characteristics of three typical working conditions are analyzed by using ADAMS; result shows that different weights have a great influence on the force deformation and vibration of the boom system of balance hoist. With the increase in lifting weight, the force and deformation of a boom system increase, lead to balance hoist unique with characteristics of indifferent equilibrium, proportional amplification, labor-saving operation will be lost, easy to cause the imbalance of balance hoist.

The purpose of this paper is to clarify the dynamic principle of internal structure of a complex morphing wing and control the wing to change configurations rapidly and smoothly. It includes modeling the dynamics of the morphing wing and designing a rational morphing control system.

The dynamic model of the morphing wing is developed based on Lagrange method of analytical mechanics. The generalized forces are obtained by virtual work principle. Since the morphing wing is a strongly coupled, over‐actuated and nonlinear system with multi‐input and multi‐output, the control system design includes a control allocator, a dynamic inversion controller and two PID controllers. The control allocator is designed based on pseudo inverse method; the dynamic inversion controller is applied to make the original system decoupled into two independent linear systems by proper nonlinear feedback transformation; two classical PID controllers are adopted for the linearlized systems.

The validity of the dynamic model and the controller is verified according to the simulation results using ADAMS and Matlab. It suggests that integrating Lagrange equation, pseudo inverse allocation, dynamic inversion control and classical PID method, is an effective way to solve problems of dynamic modeling and control for morphing wings.

The flexibility of the structure, the changes of the aerodynamic load, the mass and the dynamic performances of actuators are not taken into account. Therefore, researchers are encouraged to develop a more realistic morphing wing model.

The paper includes implications for the development of a dynamic model of a complex morphing wing and a rational morphing control system.

The paper fulfils a complete process from multi‐rigid‐body dynamic modeling to control system design for an over‐actuated nonlinear complex morphing wing, which could be a foundation of further researches on morphing wing dynamics and control.

This paper presents algorithms for computing the angular velocities of the bodies of a multibody system. A multibody system is any collection of connected bodies. The focus is upon multibody systems consisting of spherically pinned rigid bodies which do not form closed loops. Simple formulae are presented for computing the angular velocities. It is shown that once the angular velocities are known the entire kinematical description and hence, the dynamics of the system, may be developed routinely and in automated fashion. Extension to more general multibody systems follows without conceptual change in the procedures.

Discrete element methods are numerical procedures for simulating the complete behaviour of systems of discrete, interacting bodies. Three important aspects of discrete element programs are examined: (1) the representation of contacts; (2) the representation of solid material; and (3) the scheme used to detect and revise the set of contacts. A proposal is made to define what constitutes a discrete element program, and four classes of such programs are described: the distinct element method, modal methods, discontinuous deformation analysis and the momentum‐exchange method. Several applications and examples are presented, and a list is given of suggestions for future developments.

The purpose of this paper is to establish a rigid–flexible coupling model of wind turbine disc brake to simulate the actual working condition of the wind turbine brake and to study the dynamic characteristics of the compensation mechanism under different friction coefficients and braking force. It provides reference for the structure design and optimization of the compensation mechanism (compensation brake wear) in the wind turbine brake.

Based on multi-body contact dynamics theory, the rigid‒flexible coupling dynamic model of wind turbine brakes with compensation mechanism is established, in which the contact process of the components in the compensation mechanism and the phenomenon of rotation and return are described dynamically, and the rotation angle of the compensation nut and the axial displacement response of the compensation screw are calculated under different parameters.

The analysis results show that the braking reliability of the brake compensation mechanism can be effectively improved by increasing the friction coefficient of threads or increasing the friction of push rod contact surface; increasing the braking force can also improve the reliability of brake compensation mechanism, but when the braking force comes over a critical value, the effect of braking force on the reliability of the brake is very small. The braking test verifies the effectiveness of the simulation results.

Analyzing the influence of compensation mechanism on braking reliability in the braking process is of great practical significance for improving the braking efficiency and process safety of wind turbine brake.

The purpose of this study is to improve the computational efficiency and accuracy of fatigue reliability analysis.

By absorbing the advantages of Markov chain and active Kriging model into the hierarchical collaborative strategy, an enhanced active Kriging-based hierarchical collaborative model (DCEAK) is proposed.

The analysis results show that the proposed DCEAK method holds high accuracy and efficiency in dealing with fatigue reliability analysis with high nonlinearity and small failure probability.

The effectiveness of the presented method in more complex reliability analysis problems (i.e. noisy problems, high-dimensional issues etc.) should be further validated.

The current efforts can provide a feasible way to analyze the reliability performance and identify the sensitive variables in aeroengine mechanisms.

To improve the computational efficiency and accuracy of fatigue reliability analysis, an enhanced active DCEAK is proposed and the corresponding fatigue reliability framework is established for the first time.

This paper aims to investigate the lubrication performance of cam/tappet contact during start up. Especially, the thermal insulation effects of coating on the lubrication performance during cold start up process and warm start up process are studied.

A numerical model for the analysis of thermal elastohydrodynamic lubrication of coated cam/tappet contact is presented. In this model, the Reynolds equation and the energy equations are discretized by the finite difference method and solved jointly.

During start up, the contact force at cam nose-to-tappet contact decreases with increasing time, while the absolute entrainment velocity has the upward trend. The minimum film thickness, maximum average temperature and friction power loss increase with increasing time, while the coefficient of friction decreases during start up. Because of the thermal insulation effect, the coating can significantly increase the degree of temperature rise. Compared with the uncoated case, the coated cam/tappet results in a lower friction power loss. Generally, the friction power loss in the cold start up process is much higher than that in the warm start up process.

By this study, the lubrication performance and the kinematics and the dynamics of the cam/tappet during start up process are investigated. Meanwhile, the thermal insulation effect of coating is also illustrated. The difference of lubrication performance between cold start up process and warm start up process is analyzed. The results and thermal elastohydrodynamic lubrication method presented in this study can be a guidance in the design of the coated cam/tappet.

This paper discusses the issues involved in the development of combined finite/discrete element methods; both from a fundamental theoretical viewpoint and some related algorithmic considerations essential for the efficient numerical solution of large scale industrial problems. The finite element representation of the solid region is combined with progressive fracturing, which leads to the formation of discrete elements, which may be composed of one or more deformable finite elements. The applicability of the approach is demonstrated by the solution of a range of examples relevant to various industrial sections.

Robotic hands are still a long way from matching the grasping and manipulation capability of their human counterparts, but computer simulation may help us understand this disparity. We present our publicly available simulator, and describe our research projects involving the system including the development of a human hand model derived from experimental measurements.

Unlike other simulation systems, our system was built specifically to analyze grasps. It can import a wide variety of robot designs by using standard descriptions of the kinematics and link geometries. Various components support the analysis of grasps, visualization of results, dynamic simulation of grasping tasks, and grasp planning.

The simulator has been used in several grasping research problems and can be used to plan grasps for an actual robot. With the aid of a vision system, we have shown that these grasps can be executed by a robot.

We are currently developing methods to handle deformable surfaces, tendon driven models, and non‐ideal joints in order to better model human grasping.

This work is part of our current project to create a biomechanically realistic human hand model to better understand what features are most important to mimic in the designs of robotic hands. Such a model will also help clinicians better plan reconstructive hand surgeries.

We describe our publicly available grasping simulator and review experiments performed with it. The paper demonstrates the usefulness of this system as a tool for grasping research.

The purpose of this paper is to present a simple yet effective force control scheme for collaborative robots by addressing the problem of disturbance rejection in joint torque: inherent actuator flexibility and nonlinear friction.

In this paper, a joint torque controller with an extended state observer is used to decouple the joint actuators from the multi-rigid-body system of a constrained robot and compensate the motor friction. Moreover, to realize robot force control, the authors embed this controller into the impedance control framework.

Results have been given in simulations and experiments in which the proposed joint torque controller with an extended state observer can effectively estimate and compensate the total disturbance. The overall control framework is analytically proved to be stable, and further it is validated in experiments with a robot testbed.

With the proposed robot force controller, the robot is able to change its stiffness in real time and therefore take variable tasks without any accessories, such as the RCC or 6-DOF F/T sensor. In addition, programing by demonstration can be realized easily within the proposed framework, which makes the robot accessible to unprofessional users.

The main contribution of the presented work is the design of a model-free robot force controller with the ability to reject torque disturbances from robot-actuator coupling effect and motor friction, applicable for both constrained and unconstrained environments. Simulation and experiment results from a 7-DOF robot are given to show the effectiveness and robustness of the proposed controller.