In this paper, we review, compare, and analyze previous studies on vibration energy harvesting and related technologies. First, the paper introduces the basic aspects of vibration energy acquisition in the railway environment, including vibration frequency, train speed, energy flow in the train, and vibration energy harvesting potential. Generally, the methods for scavenging vibration energy caused by passing trains can be divided into four categories: electromagnetic harvesters, piezoelectric harvesters, triboelectric harvesters, and hydraulic harvesters. The structure, output performance, merits, and disadvantages of different energy harvesting strategies are summarized and compared. The application of vibration energy harvesters is explained as supplying power to monitoring sensors on the line side and the vehicle side. Finally, the paper addresses the challenges and difficulties that have not been completely resolved in the current research literature, including system stability, durability, and economy. Some recommendations to fill these research gaps are put forward for further investigation.

In recent years, with the rapid increase of railway freight, various types of self-powered sensors have been widely used in intelligent electronic monitoring equipment and on-board electric equipment in order to improve the safety and transportation efficiency of railway freight during operation. In this paper, a type of energy regeneration shock absorber based on twin slider-crank mechanisms is developed to install on the auxiliary suspensions of railway cars parallel to the coil springs. The energy regeneration shock absorber is divided into four components, as follows: a suspension vibration energy input module, a transmission module, a generator module, and an energy storage module. The suspension vibration energy input module captures the vibration energy generated by the railway car suspension. The transmission module converts the linear motion of the shock absorber into the one-way rotation motion of the generator input shaft to generate electrical energy. The energy storage module stores the electricity in the super capacitor to supply energy to self-powered sensors in railway cars. According to the bench test of the MTS ^® fatigue testing system, the peak efficiency of the shock absorber is 56.4%, and the average efficiency is 42.9%. Under harmonic excitation with a frequency of 3 Hz and an amplitude of 12.5 mm, the peak phase power is 24.6 W and the average power is 4.8 W, showing that the proposed new energy regeneration shock absorber is effective and practical to apply to self-powered sensors in railway cars.