Lodged Sugarcane/Crop Dividers Interaction: Analysis of Robotic Sugarcane Harvester in Agriculture via a Rigid-Flexible Coupled Simulation Method

As a critical component of the sugarcane harvester, the primary function of the crop dividers is to lift the lodged sugarcane (LS) and reduce the loss rate of the sugarcane harvest. In this study, a rigid-flexible coupling simulation method is proposed to improve the lifting efficiency of the crop dividers on severely LS and analyze the nature of interaction between the sugarcane stalk and the crop dividers. The model’s accuracy was verified using field experiments, and the operational performance of the crop dividers on sugarcane in different lodging postures was investigated. The results showed that the curve of the vertical height of the center (VHC) fluctuated more and slipped with highest frequency during the lifting process of side and forward LS. The speed of VHC was fastest during the lifting operation of side LS. The effect of side angle on the lifting effect of sugarcane was significant; the qualified values of the VHC of sugarcane being lifted in different lodged postures were: side and reverse lodged > side lodged > side and forward lodged. The coupling method and experimental results described in this paper can provide guidance for the optimal design and field operation of the crop dividers.

Rigid–flexible coupling dynamics analysis with joint clearance for a 5-DOF hybrid polishing robot

SUMMARY Considering the polishing requirements for high-precision aspherical optical mirrors, a hybrid polishing robot composed of a serial–parallel manipulator and a dual rotor grinding system is proposed. Firstly, based on the kinematics of serial components, the equivalent load model for the parallel manipulator is established. Then, the elastodynamic model of kinematic branched-chains of the parallel manipulator is established by using the spatial beam element, and the rigid–flexible coupling dynamic model of the polishing robot is obtained with Kineto-elasto dynamics theory. Further, considering the dynamic properties of the joint clearance, the rigid–flexible coupling dynamic model with the joint clearance for the polishing robot is established. Finally, the equivalent load distribution of the parallel manipulator is analyzed, and the effect of the branched-chain elasticity and joint clearance on the motion error of the polishing robot is studied. This article provides a theoretical basis for improving the motion accuracy and dynamic performance of the hybrid polishing robot.

Rigid-Flexible Coupling Fatigue Life Reliability Study on Bonic Fish Driving Shaft

Due to the complex loads on a bionic robotic fish operating underwater, the reliability of its working mechanism has an important effect on its overall performance. By establishing a virtual prototype model for the rigid–flexible coupling of a bionic robotic fish, we obtained the instantaneous load on the caudal fin of the robotic fish based on the flapping-wing propulsion theory with MATLAB. A rigid–flexible coupled virtual prototype model for the caudal fin drive as a flexible member of the bionic robotic fish was established, and dynamic simulations were conducted on the model. The simulations revealed the weak links in the drive shaft and established a damage level indicator and fatigue reliability analysis method based on damage theory. The behavior of fatigue reliability for different stress cycles was established, and a dynamic reliability design method with great engineering application value was proposed for virtual prototypes of rigid–flexible coupled underwater bionic robots by combining the virtual prototype technology of rigid–flexible coupling with the theory of flapping wing propulsion and the theory of random load fatigue reliability.

Dual Nozzle Weapon Power Couple Vibration Controller With Delayed Rear Nozzle

Aiming at the problem that the firing accuracy of barrel weapon is affected by the violent vibration during continuous firing, a double-nozzle vibration controller using the energy of gunpowder gas in the chamber is proposed. The synchronous external injection of the double nozzles of the controller is realized by the delayed ejection of the rear nozzles, so as to generate a power couple to balance the recoil flipping torque of the barrel weapon to achieve the stable firing effect of reducing the bore vibration. A double-nozzle vibration controller with a delayed rear nozzle for a chain gun is designed. The rigid-flexible coupling dynamic model of a chain gun with a double-nozzles vibration controller was established considering the two-phase flow of propellant gas in the barrel and airway. The numerical simulation of the muzzle vibration characteristics of the original weapon and a chain gun equipped with a double-nozzles vibration controller is carried out respectively, and the effectiveness of the double-nozzles dynamic couple vibration controller for the continuous firing vibration control of the barrel weapon is verified.