Chul-Goo Kang

Input shaping is an open-loop control technique for reducing residual vibrations in computer-controlled machines that is implemented by convolving a sequence of impulses (an input shaper) with any desired command [1]. The timing instants and amplitudes of the impulses are determined from the natural frequency and damping ratio of a vibratory system by solving a set of constraint equations [2]. Because the input shaper is generally located outside the feedback loop (Figure 1), input-shaping control does not affect the stability of the overall control system, which is a benefit compared to conventional feedback control.

A tilting train is primarily designed to achieve increased speed in a curved section without causing discomfort to passengers. Ensuring the safety of the tilting control system is one of the most important factors in such a train. This paper presents the development of a hydraulic tilting system that can measure the force in real time to find the cause of overcurrent occurring often in an actuator of a Korean tilting train. To smoothly realize tilting motion of the Korean tiling train using hydraulic actuators, the developed hydraulic tilting mechanism was designed such that synchronization control of two hydraulic cylinders installed in opposite directions was possible; furthermore, a cooling system was developed to ensure a test environment with an appropriate temperature. The actual force acting on the two hydraulic cylinders was measured and analyzed for various tilting speed of the Korean tilting train. The experimental results show that the hydraulic tilting actuator system developed for the Korean tilting train is valid. Furthermore, it is shown that two actuator loads are detected successfully acting on the hydraulic tilting system.

In railway vehicles, excessive sliding or wheel locking can occur while braking because of a temporarily degraded adhesion between the wheel and the rail caused by the contaminated or wet surface of the rail. It can damage the wheel tread and affect the performance of the brake system and the safety of the railway vehicle. To safeguard the wheelset from these phenomena, almost all railway vehicles are equipped with wheel slide protection (WSP) systems. In this study, a new WSP algorithm is proposed. The features of the proposed algorithm are the use of the target sliding speed, the determination of a command for WSP valves using command maps, and compensation for the time delay in pneumatic brake systems using the Smith predictor. The proposed WSP algorithm was verified using experiments with a hardware-in-the-loop simulation system including the hardware of the pneumatic brake system.