Due to its vibration reduction and error compensation capabilities, diaphragm couplings are widely used in marine multi-gearbox systems. However, due to the existence of factors such as installation error, system load deformation and asymmetric elastic support, the coupling will inevitably produce misalignment and affect the operation of the gear system. This paper proposesed a calculation method for the quasi-static contact characteristics of the gear pair considering the diaphragm coupling misalignment. By combining the coupling misalignment model, the meshing misalignment model, the system static equilibrium equation and the tooth surface load contact analysis model (LTCA) to construct an iterative calculation process, the contact characteristics analysis of the gear pair under the non-ideal meshing condition caused by the coupling misalignment was realized. Taking the double-gearbox transmission system in the multi-gearbox transmission system of ships as the research object, the influence of coupling misalignment and load torque on the meshing characteristics of the double-helical gear pair was studied. The research results show that the misalignment of the coupling on the double-helical gear near the coupling has a greater impact so that the tooth surface load is asymmetrically distributed, the tooth surface appears disengaged area, away from the coupling gear is not affected by it. As the amount of misalignment increases, the amount of meshing misalignment increases, the gear pair disengagement area increases, the actual contact line length becomes smaller, and the gear pair meshing stiffness decreases. At light loads, the gear pair contact state is more sensitive to coupling misalignment. The tooth surface will produce a large disengagement area and the mesh stiffness curve changes significantly. With the increase of torque, the tooth surface reaches the complete contact state. With the increase of torque, the tooth surface reaches a complete contact state, and there is no disengagement area on the tooth surface. However, due to the misalignment force of the coupling, the meshing misalignment between the left and right tooth surfaces of the double-helical gear pair is asymmetric, so the tooth surface presents the phenomenon of partial load.

The vibration of the spool caused by the change of the medium flow near the spool of the hydraulic valve has an important influence on the stability and service life of the poppet valve. In order to investigate the three-dimensional vibration characteristics of the poppet valve, this paper proposed a visual experiment method based on virtual binocular vision, and obtained the image sequence of the valve core vibration. The spatial coordinate value of the geometric vertex of the spool was obtained by fitting the outline of the spool, which improves the measurement accuracy of the spool position. By analyzing the vibration characteristics of the valve core under different inlet and outlet pressures, spring stiffness, and other conditions, it is shown that the spatial range and impact degree of the valve core vibration are closely related to the operating conditions of the hydraulic system and the valve core structure. When the inlet pressure increases from 3.2 MPa to 4.4 MPa, the vibration of the valve core gradually intensifies, and the dispersion increases; when the precompression amount increases from 14 mm to 17 mm, the valve core vibration tends to be stable and the dispersion decreases. In addition, with the increase of the spring stiffness and the valve core half cone angle, the dispersion of the valve core vibration also shows a trend of decreasing firstly and then increasing, and its minimum values appear when the spring stiffness is 2 N/mm and the valve core half cone angle is 30°. In the projection of the spool vibration along the axial, front, and side directions, the waveform factor of the side radial vibration is larger than that of the front radial, while the waveform factor of the axial vibration is the smallest. The variation trend of the waveform factor is consistent with the variation trend of the dispersion. The dispersion of the valve core vibration is positively correlated with the waveform factor, and the waveform factor is the smallest when the valve core half cone angle is 30° and the spring stiffness is 2 N/mm. The research results can provide theoretical support for the structural design of the hydraulic valve with the poppet valve structure, thereby improving the stability of the hydraulic system and reducing the damage to the hydraulic valve caused by vibration.

The soft actuators are flexible in nature, and as an end-effector, it can realize functions that are difficult to be achieved by the traditional rigid actuator, such as flexible grasping and flexible motion. Moreover, it is friendly to human body and has a high degree of security in human-machine interaction. This paper presented a teleoperation and end force feedback system of soft actuator. Its control was studied based on kinematic model and force feedback method. The bending model, elongation model and force feedback model were established, and the control method and control flow were presented. Through a pair of handles, the operator realized the remote control of the soft actuator located in another physical space, which can not only control the soft actuator to bend in any direction, but also control its elongation with the same curvature. The soft actuator is composed of three bellows uniformly arranged in the circumferential direction, and the force feedback effect of the end is realized by the pneumatic components inside the handle. The pair of handle is a new type of main hand structure, including handle A and handle B, which control bending and elongation of soft mechanical arm respectively. Handle B has a certain force sense of presence. The proposed system was experimentally verified, and the functions of the soft manipulator were proved in the bending, elongation and force feedback stages, and the skin model was equipped to verify the functions of the soft actuator as the end-effector in the ultrasonic detection scene. The experimental data show that the pressure at the ends of soft actuator is 7 N, force feedback control loop time is around 1 s. The system established in this paper, on the one hand, plays the flexibility of the soft actuator, on the other hand, it also increases the function of remote control, and has a powerful sense of presence, which can be widely used in telemedicine, massage and other fields in the future.

To meet the requirements of the high-precision operation of the hydraulic manipulator in a complex environment, it is necessary to equip it with an accurate force measurement system. Due to the large and complex end-effector contact force against the working environment, the force sensor is vulnerable to damage. Therefore, focu-sing on the accurate measurements of the terminal force with force sensorless, this paper proposed a force soft-sensing method of hydraulic manipulator based on joint torque compensation, taking 3-D of hydraulic manipulator as the research object. A finite Fourier series model was used to design the excitation trajectory, and the recursive least squares method was used to identify the dynamics parameters of the manipulator. The nonlinear friction torque model was used to replace the Coulomb viscous friction model to improve the precision of manipulator dynamics model. A neural network joint torque compensation model was established to reduce the influence of uncertain factors on the precision of the dynamics model. The AMESim/Simulink co-simulation model was built to design the triangular trajectory of the hydraulic manipulator end-effector, which verified the high accuracy of the dynamic model proposed in this research. A constant force load of 500 N and a variable force load of 0~500 N were applied to the horizontal and vertical direction of the end-effector respectively. Under the constant force load, the soft sen-sing accuracy of the end force in the horizontal and vertical directions is 4.84% and 2.79%, respectively. Under the variable force load, the accuracy of the soft sensor can reach 5.73% in the horizontal direction and 4.81% in the vertical direction. By comparing the end force soft sensor accuracy with that before optimization, it is verified that the force soft-sensing model of hydraulic manipulator based on joint torque compensation can effectively improve the accuracy of end-effector contact force.

The recirculating planetary roller screw mechanism is a transmission mechanism that is engaged by the screw or nut thread and multiple circular groove rollers. This study theoretically analyzed the working principle and motion relationship of the recirculating planetary roller screw mechanism, and established the 3D model of the recirculating planetary roller screw mechanism. The 3D model was imported into the multi-rigid-body dynamics simulation software ADAMS, and the reasonable connection relationship of virtual prototype was set. The dynamics analysis was carried out and related parameters such as angular speed, velocity, force and torque were extracted. The results show that the simulated value of roller angular speed is 28.28 rad/s, the angular speed of roller is -5.20 rad/s, the nut movement velocity is 1.98 mm/s, and the nut displacement is 2 mm. The above values were compared with their corresponding theoretical values, and the error was found to be less than 5%, thus verified the correctness of the simulation results. The contact force of the roller contacting with the screw and the nut respectively presents sine curve characteristics in the nut threadless area.When the load is 5, 10 and 15 kN, the maximum peak of the collision force between the same roller and convex platform of cam ring under different loads are 113.92, 32.31 and 54.08 N, respectively. Besides, the fluctuation range of the maximum peak of the collision force between diffe-rent rollers and convex platform of cam ring under the same load is similar to the above values, thus the collision force between the roller and convex platform of cam ring peak value is not affected by the load size. The collision torque between the roller and the carrier increases under higher load; the angular speed of the roller begins to change in the nut threadless area during the operation of the recirculating planetary roller screw mechanism, and the maximum sudden change occurs at the contact between the roller and the convex platform of cam ring. This study has certain reference significance for optimizing the overall performance of the recirculating planetary roller screw mechanism.