导致电梯突然反向的控制软件问题分析与解决

Implied defect in control software causes elevator suddenly reverses when sensor conks out

采用可编程控制器控制的电梯在目标楼层的层定位传感器失效后,电梯轿厢会在运行至同方向上的下一层站时突然反向,在目标楼层的上一层和下一层之间振荡运行。为此,分析了原控制软件,指出了电梯定向模块程序的隐含缺陷,给出了在不增加系统物理构件的基础上对此软件缺陷的修正思路及其验证程序,给出了3种软件模式方法来提高安全紧要需求的控制系统的安全性。在目标电梯上验证了该方法的可行性和可靠性。

An elevator controlled by a programmable logic controller would suddenly reverses when the sensor which is used to detect the target floor conks out. Then it incessantly vibrates between the pre-vious floor of target and the next one. This implied defect in the control software is found out and corrected. The software design patterns improving the safety of the control soft- ware are discussed. Three methods which based on the secure software pattern method are presented to enhance the security of this elevator, which requests the need of safety-critical. Then the feasibility and reliability of those methods are validated in the target elevator.