| Heavy duty forging manipulator is a large production equipment with the free forging press to forge the forging pieces. Under gripping the hundreds of tons of forging piece with four meters diameters, the heavy duty forging manipulator’s single tongs rotation systems can’t drive the large forging pieces, so it needs using the parallel driving systems to realize the rotation of forging piece. However, the kinetic difference of driving parts, backlash and friction between parts for the parallel driving systems of forging manipulator causes the unbalance loading, force distortion and other undetermined behaviour of force, reducing the working life of the parallel driving systems, and causing the driving disabler. So it needs further studying the load balance of the parallel driving systems.Because forging manipulator assistants with free forging press to realize coordinating motion, the parallel driving systems need discontinuous rotary motion under the start-stop frequently and quickly. The gear transmission is in the intermittent driving with rectangular impulse under the gear impacting states, which is more serious because of gear backlash. Moreover, the dynamical variation of the parallel driving systems such as interaction force of gear transmission is difficulty to be measured directly from the experiment. So it needs an effective calculation method to solve the gear contact/impact dynamics equation to analyze the gear impact dynamics behaviour under the intermittent driving. In addition, because there are large inertia and variation of load, strong nonlinear charactreristics of hydraulic systems, dead zone of the control valves, gear backlash, friction nonlinear in the parallel driving systems of forging manipulator, influncing directly the position and load balance of the parallel driving systems of forging manipulator under the time variation heavy conditions, so it needs load balance analysis and load balance control for the parallel driving systems of forging manipulator.Therefore, the studies on the parallel driving systems of forging manipulator are conducted in the present paper as follows:A momentum iterative solution approach based on Newmark direct integration method is proposed for the gear contact/impact problem under the intermittent rotation. This solution method can convert the conventional second-order equation of motion in force equilibrium into another first-order momentum equation and further smooth out the rapid changes of discontinuous rotation produced by start-stop frequently. The validation of accuracy and convergence using momentum analytical approach based on Newmark direct integration method is demonstrated by simulating the contact/impact of intermittent gear transmission using3D finite element dynamical software and experiments.A gear transmission interaction force model is proposed to analyze the heavy duty and intennittent gear transmission interaction force characteristics of forging manipulator based on the contact model of robotic system. The inertia, gear backlash and contactratio are introduced into the proposed model, which is simplified to the identification model using an appropriate switching function. Furthermore, a developed least square based iterative parameter estimation method is introduced to estimate some parameters of the interaction force model. The relevant experiment is implemented to validate the simulation results of the proposed model.For many complexity and nonlinearity factors of the actual tongs parallel rotation systems of forging manipulator, the parallel driving dynamics model of the forging manipulator is made based on the single rotary driving system. The load balance and position of forging manipulator is simulated and analyzed for the dynamical difference factors of forging manipulator such as oil pressure, valve friction and motor displacement of hydraulic systems, stiffness coeffiencient and backlash of gear transmission. The simulation results indicat that these factors cause different influence significantly for the load balance or position of the parallel driving systems of forging manipulators.The internal model control and the torque error compensation feedback control are employed for the load balance control of forging manipulators The dynamical difference factors of forging manipulator are analyzed by the simulation and experiment of load balance control, it indicates that the load balance control strategy meet basicly the load balance control requirement that it realize load balance and start-stop quickly simultaneously for the parallel driving of forging manipulator gripping systems.In fact, many complexity and nonlinearity factors of the actual tongs parallel rotation systems of forging manipulator can produce error of system model. In oder to further improve the load balance control performance with start-stop quickly, the approximate internal model based neural network is updated by the experiments. Then the approximate internal model-based neural control (AIMNC) and the torque error compensation feedback control are employed for the load balance control experiment of forging manipulators. Through the simulation analysis, the control stratagem is validation for the load balance control. |
PDF Full Text Request