【正文】 these valves, the relation between spool displacement and open area is nonlinear. Then, in automatic operation, using this relation, the spool displacement is inversely calculated from therequired open area, and the nonlinearity is pensated Fig. 5. Nonlinear pensation. . State feedback Based on the model discussed in Section 2, if the dynamic characteristics for boom angle control are linearized in the vicinity of a certain standard condition?spool displacement X , cylinder differential 10 pressure P , and boom angle u ., the closedloop transfer function can be expressed by where, K is position feedback gain。 γ soil density。 Vi soil volume in the cylinder and piping。 Pi scylinder headside pressure。 Xi sspool displacement。 mean boom arm, and bucket, respectively.) . Hydraulic model Each joint is driven by a hydraulic cylinder whose flow is controlled by a spool valve, as shown in Fig. 3. We can assume the following: 1. The open area of a valve is proportional to the spool displacement. 2. There is no oil leak. 3. No pressure drop occurs when oil flows through piping. 4. The effective sectional area of the cylinder is the same on both the head and the rod this problem, for each joint, we have thefollowing equation from the pressure flow characteristics of the cylinder: when, where, Ai seffective crosssectional area of cylinder。 Operation 1. Introduction A hydraulic shovel is a construction machinery that can be regarded as a large articulated robot. Digging and loading operations using this machine require a high level of skill, and cause considerable fatigue even in skilled operators. On the other hand, operators grow older, and the number of skilled operators has thus decreased. The situation calls forhydraulic shovels, which can be operated easily by any person w1–5x. The reasons why hydraulic shovel requires a high level of skill are as follows. 1. More than two levers must be operated simultaneously and adjusted well in such operations. 2. The direction of lever operations is different from that of a shovel’s attachment movement. For example, in level crowding by a hydraulicshovel, we must operate three levers ?arm, boom, bucket. simultaneously to move the top of a bucketalong a level surface ?Fig. 1.. In this case, the lever operation indicates the direction of the actuator, but this direction differs from the working direction. If an operator use only one lever and other freedoms are operated automatically, the operation bees very easily. We call this system a semiautomatic control we develop this semiautomatic control system, these two technical problems must be solved. 1. We must use ordinary control valves for automatic control. 2. We must pensate dynamic characteristics of a hydraulic shovel to improve the precision of control. Fig. 1. Level crowding of an excavator and frame model of anexcavator. We have developed a control algorithm to solve these technical problems and confirm the effect of this control algorithm by experiments with actual hydraulic shovels. Using this control algorithm, we have pleted a semiautomatic control system for hydraulic shovels. We then report these items. 2. Hydraulic shovel model To study control algorithms, we have to analyzenumerical models of a hydraulic shovel. The hydraulic shovel, whose boom, arm, and bucket joints are hydraulically driven, is modeled as shown in . The details of the model are described in thefollowing. Fig. 2. Model of hydraulic shovel. . Dynamic model [6] Supposing that each attachment is a solid body, from Lagrange’s equations of motion, the following expressions are obtained: 其中 K sm 1 g。 Feedforward。Semiautomatic control system for hydraulic shovel Abstract A semiautomatic control system for a hydraulic shovel has been developed. Using this system, unskilled operators can operate a hydraulic shovel easily and accurately. A mathematical control model of a hydraulic shovel with a controller was constructed and a control algorithm was developed by simulation. This algorithm was applied to a hydraulic shovel and its effectiveness was evaluated. High control accuracy and highstability performance were achieved by feedback plusfeedforward control, nonlinear pensation, state feedback and gain scheduling according to the attitude. Keywords: Construction machinery。 Hydraulic shovel。 State feedback。 and gsgravitational acceleration. 3 3 g 3 θi is the joint angle, τi is the supply torque, li is the attachment length, lgi is the distance between