液壓挖掘機(jī)的半自動(dòng)控制系統(tǒng)外文翻譯-液壓系統(tǒng)(編輯修改稿)
2025-02-24 03:47 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 after the control started, load disturbance Fig. 6. Block diagram of control system (Z). Fig. 7. Gain scheduling according to the attitude. was applied stepwise. Fig. 9 shows the use of feedforward control can reduce control error. 6. Semiautomatic control system Based on the simulation, a semiautomatic control system was manufactured for trial, and applied to the SK16 shovel. Performance was then ascertained by field tests. This section will discuss the configuration and functions of the control system. . Configuration As illustrated in Fig. 10, the control system consistsof a controller, sensors, man–machine interface,and hydraulic control system. The controller is based on a 16bit microputer which receives angle input signals of the boom, arm, and bucket from the sensor。 determines the condition of each control lever。 selects control modes andcalculates actuating variables。 and outputs the results from the amplifier as electrical signals. The hydraulic control system generates hydraulic pressureproportional Fig. 8. Simulation result of level crowding. to the electrical signals from the electromagic proportionalreducing valve, positions the spool of the main control valve, and controls the flow rate to the hydraulic cylinder. In order to realize highspeed, highaccuracy control, a numeric data processor is employed for the Fig. 9. Effect of feedforward control on control error of Z. Fig. 10. Schema of control system. controller, and a highresolution magic encoder is used for the sensor. In addition to these, a pressure transducer is installed in each cylinder to achieve pressure feedback. The measured data are stored up to the memory, and can be taken out from the munication port. . Control functions This control system has three control modes,which are automatically switched in accordance with lever operation and selector switches. These functions are the following (1). Level crowding mode: during the manual arm pushing operation with the level crowding switch, the system automatically controls the boom and holds the arm end movement level. In this case, the reference position is the height of the arm end from the ground when the arm lever began to be operated. Operation of the boom lever can interrupt automatic control temporarily, because priority is given to manual operation. (2) Horizontal bucket lifting mode: during the manual boom raising operation with the horizontal bucket lifting switch, the system automatically controls the bucket. Keeping the bucket angle equal to that at the beginning of operation prevents material spillage from the bucket. (3) Manual operation mode: when neither the level crowding switch nor the horizontal bucket lifting switch are selected, the boom, arm, and bucket are controlled by manual operation only. The program realizing these functions is primarily written in C language, and has wellstructured module to improve maintainability. 7. Results and analysis of field test We put the field test with the system. We confirmed that the system worked correctly and the effects of the control algorithm described in Chaps. 3 and 4 were ascertained as follows. . Automatic control tests of indi213。idual attachments For each attachment of the boom, arm, and bucket, the reference angle was changed 58 stepwise from the initial value, and the responses were measured。 thus, the effects of the control algorithm described in Chap. 3 were ascertained. . Effect of nonlinear pensation Fig. 11. Effect of nonlinear pensation on boom angle. Because dead zones exist in the electrohydraulic systems, steadystate error remains when simple position feedback without pensation is applied in the figure.. Addition of nonlinear pensation in the figure. can reduce this error. . Effect of state feedback control For the arm and bucket, stable response can be obtained by position feedback only, but adding acceleration or pressure feedback can improve fastresponse capability. As regards the boom, with only the position feedback, the response bees oscillatory. Adding acceleration or pressure feedback made the response stable without impairing fastresponse capability. As an example, Fig. 12 shows the test results when pressure feedback pensation was applied during boom lowering. . Le213。el crowding control test Control tests were conducted under various controland operating conditions to observe the control Fig. 12. Effect of pressure feedback control on boom angle. Fig. 13. Effect of feedforward control on control error of Z. characteristics, and
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