Development of On line Test Method to Simulate Earthquake Responses by Utilizing Linear Motor Drive

在线计算机测试控制方法在许多国家和日本广泛应用，并得到了许多研究者的检验、接受和改进。该方法成功进行结构模型地震反应试验的关键技术是执行器行程位移的精确控制以及位移和载荷的精确测量。在线试验中广泛使用的电伺服控制液压执行器存在结构缺陷、刚度不足和油压脉动等问题。在多自由度系统的测试中，这些缺陷有时会被夸大，因为在多自由度系统中，必须根据运动方程的解析计算结果，根据计算机的命令同时控制一些执行机构。为了克服这些缺陷，开发了新型的在线测试系统。所开发的一种系统包括一个数控电动机，一个带有滚珠丝杠的传动装置，该传动装置将电动机的旋转动力转化为平移运动，以及一台控制整个测试过程的微型计算机。另一种系统采用直线电机直接定位系统代替螺杆式定位系统。使用这些系统的许多优点是可以计算出来的。其中，必须强调的优点是，加载杆可以保持在所需的精确位置。在多自由度系统的情况下，例如多层测试框架，执行器的位移控制必须不受其他执行器运动的影响。液压执行器往往不能满足这一要求。采用不同的控制系统对多个试验结构进行了测试，找出了最佳的控制方案。在最合适的程序下，得到的响应位移精度很高。螺杆式控制误差可控制在20 μ m以内，直喷式控制误差可控制在5 μ m以内。少

The on-line computer test control method, widely utilized in many country as well as in Japan, has been examined, accepted, and improved by many researchers. The key techniques for the success of the earthquake response test of a structural model by this method are the accurate displacement control of the strokes of actuators and the precise measurements of displacements and loads.Hydraulic actuators with electro-servo control widely used in the on-line tests have the constitutional weaknesses, the insufficient rigidity and the pulsation in oil pressure. These deficiencies are sometimes exaggerated in tests on multi-degree of freedom systems where some actuators must be simultaneously controlled according to the commands from the computer based on the interration calcuation results of the equation of motion.To overcome these defects new types of the on-line test system have been developed. One system developed comprises a numerical-controlled electric motor, a trnsmission device with a … More ball screw which converts thw rotational power of the motor into translational movemants, and a micro-computer which controls the whole test procedure. amother system unilized a linear-motor firect drice instead of the screw-type positioning system.Many advantages of using these systems can be counted up. Among them, the advantage that the loading rod can be held at the exact positions required must be emphasized. Im the case of a culti-degree of freedom system, for example, a multi-story test frame, the displacement control of an actuator must be protected from the movements of other actuators. The hydtaulic actuators often fail in fulfilling this requirements.Several test structures were rested by using verious control system to find out the best control program. Under the most suitable program, the results show very high preciseness in the obtained response displacement. The control error could be surpressed within 20 microns for the screw-type system, and 5 microns for the direct dfive system. Less