XYY01-130@烟机液压系统总体及压紧部分设计
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XYY01-130@烟机液压系统总体及压紧部分设计,机械毕业设计全套
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Hydraulic excavators semi-automatic controlled system Abstract A hydraulic excavators used in the semi-automatic controlled system is developed. Because of this system, even unskilled operators can easily and accurately controlled hydraulic excavators. Constructed with the hydraulic excavator controller of mathematical precision control model through simulation to develop a control algorithm, which is used in hydraulic excavators, We can estimate its efficiency. In accordance with the law, through positive feedback and feed forward control, nonlinear compensation. state feedback and gain scheduling, and other means to obtain higher accuracy and stability properties. Keywords : construction machinery; Hydraulic excavators; feed forward; State feedback; Operation 1 Introduction hydraulic excavators, known as the large articulated robot, a construction machinery. Using this machine excavation and loading operations, require drivers to have high operational skills, Even skilled driver would have considerable fatigue. The other hand, with the operators age increased, the number of skilled drivers thus will be reduced. Developed a way to let anyone will be able to easily manipulate the hydraulic excavator is very necessary. Hydraulic excavators asked for a higher operational skills, for the following reasons. 1. Hydraulic excavator operation, at least two joystick operation and must be coordinated. 2. Joystick moves charged with the direction of the Jib components of the campaign in different directions. For example, the hydraulic excavator backhoe level action, we must also play three joystick (boom, the bucket handles, Bucket) to enable the bucket along the top of the horizontal movement. In this case, joystick operation shows the ntscomponents of the implementation of the direction of movement, but this direction and work in different directions. If a driver to operate as long as the control rod, bar and other free arm automatic servo action, operation becomes very simple. This is the so-called semi-automatic control system. Development of a semi-automatic control system, we must address the following two technical problems. 1. Automatic control systems must use common control valve. 2. Hydraulic excavators must compensate its dynamic characteristics to improve its accuracy. 2 Hydraulic excavator model To study the hydraulic excavator control algorithm, hydraulic excavators must analyze the mathematical model. The hydraulic excavator boom, the bucket handles, and the bucket is driven by fluid pressure. 2.1 Dynamic model Assumes that each of the Jib components are rigid, the Lagrange equations of motion can be in the following expression : where g is the acceleration due to gravity; i hinged angle; i is the component of torque ; li length; lgi shaft to the centers focus away from the quality ;mi components; Ii is the focus of the moment of inertia (subscript i=1-3; were expressed boom, the bucket handles, and the bucket). 2.2 Excavator model ntsComponents of each arm are driven by hydraulic cylinder, hydraulic cylinder and flow control of the slide valve. Can make the following assumptions : 1. Hydraulic valve opening and valve core proportional to the displacement. 2. System hydraulic oil leak. 3. Hydraulic oil flows through the pipeline when no hydraulic pressure loss. 4. Cylinder rod and the top of both sides are equally effective regional. On this issue, each arm components from the hydraulic cylinder pressure and flow characteristics may come to the following equation : When ; Among them, Ai hydraulic cylinder is an effective cross-sectional area ;hi hydraulic cylinder is the length ;Xi sliding core is the location; Psi ;P1i of supply pressure is the maximum cylinder pressure ;P2i side of the cylinder rod edge pressure; Vi is the hydraulic cylinder and the oil pipeline is ;Bi slide valve width; is the density of oil molecules, K oil viscosity; c is the flow coefficient. 2.5 Slide valve characteristic Slide valve movement of the hydraulic excavator control characteristics have considerable influence. Thus, the assumption that Valve relative reference input following an order delay. Which is sliding core displacement reference input; Is time constant. 3 angle ntsAngle control system is basically a servo reference input through the angle position feedback control. To obtain more accurate control, nonlinear feedback and compensation by adding location feedback. 3.1 nonlinear compensation In ordinary automatic control systems, often used as servo valve of this new type of control device. In semi-automatic control system, in order to achieve automatic control and manual coordination, the use of manually controlling the valve. This type valve, the displacement of the spool valve with the opening of the relationship is nonlinear. Therefore, the control operation, the use of such a relationship, spool displacement may be required by the valve opening to the anti-launched. Meanwhile, non-linear compensation can be. 3.2 Feedback on the first two models Discussed on the basis of If the boom angle to the dynamic characteristics of a certain standard and the location of the linear approximation of (slip displacement X-10, Cylinder pressure difference P 110, boom angle 10), the closed-loop transfer function for which , Kp location of the feedback gain coefficient; Because the system is smaller coefficient a1, the reaction is unstable. For example, large hydraulic excavator SK-16 China. X10 is 0, the coefficient is given a0=2.7 10, a1=6.0 10. a2=1.2 10. add acceleration ntsfeedback magnification factor Ka, hence the closed-loop transfer function is the addition of this factor , Coefficient on the big S, the system tends to be stable. Visibility, using acceleration feedback to improve the response characteristics obviously. However, it is very difficult to accurately measure the acceleration. To avoid this problem, use hydraulic cylinder force feedback replace acceleration feedback. Therefore, the hydraulic cylinder measured by the strength of the cylinder pressure calculation and removes some of its low frequency. This is the so-called pressure feedback. 4 Semi-automatic control system Based on the simulation experiments, on the basis of semi-automatic control system has been created, Application of the type excavator SK-16 test. Field Test verifiable through its operability. This section will discuss the control system structure and function. 4.1 The structure Of control by the controller system, sensors, human-machine interface and hydraulic system. Controllers are used by the microprocessor 16, will receive automatically boom, bucket handles, and the bucket angle sensor input signal, Each joystick control of the location, the selection of control mode and calculate the actual amount of change, to the signal from the amplifier to form the output signal. Hydraulic control system of fluid pressure and the electromagnetic signal proportional valve proportional, ntsdominated the slide-valve position control into the hydraulic cylinder hydraulic oil flow. In order to obtain high-speed, high-precision control, the controller using digital processing chip, Sensors using high-resolution magnetic encoder. In addition, in each cylinder pressure sensor installed on the pressure in order to obtain feedback signal. After the above data on the existence of memory, communication ports can be read out. 4.2 The control function control system has three control mode, can operate under the bar and choice of switching automatic switching. Their specific functions as follows. (1) Backhoe level action mode : water Switches vindicated shovel, bucket in hand with promoting stem operation, The control system automatically handles the Big Dipper and the Big Dipper handle to maintain the bottom of the horizontal movement. In such circumstances, when the fighting began stalk control rod operation, the location of its information from the ground to the bottom of the bucket stalk height. Operation of the boom pole manual operation can be suspended automatic control, because the manual operation of the priority over the control. (2) Lift bucket level model : Bucket Lift Switches level in the manual boom lifting operation, Automatic Control System bucket. Bucket perspective to maintain its lifting has just begun when the angle to prevent the raw materials from leaking bucket. (3) the manual mode of operation : When neither option backhoe level action pattern, and have no choice bucket level Lift mode, boom, the bucket handles, and the bucket is only through manual operation. System mainly uses the C programming language to accomplish these functions to create a stable module to improve system stability. nts5 individual components for the control test boom The bucket handles, and the components of each bucket, to 5 gradient from the initial value began to change their point of reference value, measured response, thereby ascertain the three description of the role of the control algorithm. 5.1 Nonlinear compensation Because of the role of electro-hydraulic system is insensitive, When only a simple position feedback without compensation, steady-state error still exists. Nonlinear compensation to reduce such errors can emerge. 5.2 The state feedback control For the role of the Big Dipper handle and the bucket, position feedback can only stable response However, acceleration or increase pressure feedback improves the response speed. To boom as an example, only only position feedback, the response became unstable. Acceleration or to pressure feedback, in response to the improved stability. 6 backhoe level control testing In various locations to control and operate under the control test, in its control characteristics, Meanwhile determine the optimal control parameters. 6.1 feed forward control Is the only position feedback circumstances, increased magnification factor Kp reduce Z errors, causing instability, resulting in system delay, for example, as shown in Figure 13 of the customs and Kp is not reduced. Adopt 4.1 described in the bucket handle the Jib feedforward control can reduce the errors will not increase Kp. 6.2 Location of compensation ntsWhen the backhoe up position at or backhoe moves are completed, backhoe level action tends to instability. Oscillatory instability may change its position magnification factor Kp to eliminate the discussion. their role in the show backhoe from about two meters to the level when action results. Compensation is not equipped with the devices, compared to map the relationship did not loaded, the situation of compensation is to provide a stable response. 6.3 The control layout on the role of control-operated Control interval, the study results are as follows : 1. When the interval set up the control over 100ms, unstable oscillation due to the inertia movement intensified with the position. 2. When the interval below routing control, the control can not operate for such a large increase. Therefore, in consideration of accuracy, control system selected interval control circuits. 6.4 By the use of load Control system, hydraulic excavators implementation of practical mining moves to study its impact on the set. Control precision not found with no load is quite different. 7 Conclusions This paper shows that state feedback and feed forward control portfolio, precision control of hydraulic excavators possible. It also proved that ordinary nonlinear compensation can control valve used in
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