This paper presents the design, modeling and bench testing of a smart railroad tie for energy harvesting from the motion of railway track. The system is intended for applications that require trackside power in remote locations, such as wayside electrical devices and safety equipment, signal lights, crossing gates, wireless communication, as well as rail health monitoring systems. The smart tie, which is designed to have similar dimensions to a conventional railroad tie, is installed in the same manner as a standard tie on the track. In particular, the mechanical energy harvesting module and its corresponding power management unit can be both embedded inside a composite, concrete or wooden tie, in order to shield the components from the harsh environment and protect the system against any potential theft or vandalism. Different from other railway track harvesters that typically harvest energy from bidirectional track deflections, the proposed smart tie only harvests the kinetic energy of the track when the wheels push it downwards, which resolves the preload and installation challenges of bidirectional harvesting and increases the overall system reliability. A nonlinear analytical model is developed to analyze the dynamic characteristic of the system and the simulation is conducted to predict the performance. Bench tests are subsequently carried out under both harmonic and recorded tie displacement inputs to validate the model and assess the harvesting performance. During the bench tests, the generator shaft was observed to start rotation at 0.1 mm vibration amplitude, indicating that the overall prototype has a relatively small backlash. In-lab test results indicate that an average power of 26.1–42.2W on 4 Ohms and 2 Ohms external loads were achieved under simulated tie movement recorded from a service track.

With the development of high-speed rail technology, the interaction between wheel and track becomes more serious, which threatens the running stability, riding quality and safety of the vehicle. Due to the selected stiffness and damping parameters, conventional passive suspensions cannot fit in with the diverse conditions of the railway. Additionally, among these vibrations contains a large amount of energy, if this vibrational energy can be recycled and used for the active suspension to control, it will be a good solution compared to the conventional passive suspensions. Many energy-harvesting shock absorbers have been proposed in recent years, the most popular design is the electromagnetic harvester including linear electromagnetic shock absorbers, rotational electromagnetic shock absorbers, the mechanical motion rectifier (MMR), and the hydraulic electromagnetic energy-regenerative shock absorber (HESA). With different energy converting mechanisms, the complicated effects of the inertia and nonlinear damping behaviors will severely impact the vehicle dynamic performance such as the ride comfort and road handling. In the past few years, engineers and researchers have done relevant researches on HESA which have shown that it has good effects and proposed several suspension energy regeneration solutions for applying to car. This paper presents a novel application of HESA into a bogie system for railway vehicles comparing to the conventional suspension systems. HESA is composed of hydraulic cylinder, check valves, accumulators, hydraulic motor, generator, pipelines and so on. In HESA, the high-pressure oil which is produced by shock absorber reciprocation could be exported to drive the hydraulic motor, so as to drive the generator to generate electricity. In this way, HESA regenerate the mechanical vibrational energy that is otherwise dissipated by the traditional shock absorber as heat energy. Because the bogie has two sets of suspension systems, a dynamic model of bogie based on AMESim is established in order to clarify the influence of the dynamic characteristics effect and the energy harvesting efficiency when installing the HESA into different sets of the bogie. Then, set the HESA model into each suspension system of the bogie and input with the corresponding characteristic excitation, the influence of the dynamic characteristics and the energy harvesting efficiency are analyzed and compared. The simulation results show that the system can effectively reduce the vibration of the carriage, while maintaining good potential to recycle vibratory energy. Based on the results of the simulation, the relationships as well as differences between the first suspension system and second suspension system have been concluded, which are useful for the design of HESA-Bogie. Moreover, comparing the energy harvesting efficiency discrepancy between the two suspension systems, the potential of energy harvesting of a novel railway vehicle bogie system with HESA has been evaluated and then the best application department has been found, which indicates the theoretical feasibilities of the HESA-bogie to improve the fuel economy.

With the increasing of the train load, the wheel-rail wear is worsening, the maintaining and replacing cycle is shortened enormously, the problem of replacing steel rail and wheel prematurely not only make the railway transportation cost increasing, but also affect the railway normal transportation. This paper proposes a novel type of active energy self-supply radial steering technology — the parallel interconnection hydraulic-electric energy-harvesting active radial steering bogie system. This system is a typical “machine – electric – hydraulic” coupling system, which includes parallel interconnection hydraulic-electric energy-harvesting suspension and active radial steering bogie, consisting of mechanical, electronic, hydraulic and control subsystems internally. In this system, the radial steering bogie is equipped with four HESA, and HESA can reuse the mechanical vibration energy which used to be transformed into waste heat by the shock absorber. In this system, the mechanical vibration energy is now used to drive power module of active radial steering bogie, so as to implement the train’s active radial steering without external power supply. This paper discusses the evolution of radial steering bogie in general, and introduces the structure and basic principle of the parallel interconnection electro-hydraulic energy-harvesting active radial steering bogie system. The system establishes a model of the parallel interconnection hydraulic-electric energy-harvesting shock absorber. The typical vertical irregularity of American track is established. In the paper, we research on the system’s damping performance and energy recovery performance through stimulation. Simulation results show that the maximum vertical acceleration of train body is reduced from 42.9% to 62.3%, and the average energy recovery power from the system increases from 217W to 1835W when the system works at the six levels of track irregularities.

Wireless Sensor Networks have been a focus of research in the North American freight railroad industry to enable on-board real-time sensing of critical railcar parameters. Important railcar aspects like wheel bearing temperature, air pressure, brake failure, and the integrity of transported goods can then be monitored closely and reliably. This enables immediate preventive actions in case of impending failures and also enables trend analysis that can be used to fine-tune maintenance efforts on railcars. These measures increase the safety, efficiency, and dependability of freight railroad operations. In our previous work [1–3] we have presented our Hybrid Technology Networking (HTN) protocol. This protocol provides optimal network performance for railcar monitoring applications. We have also presented HTNMote, a hardware prototyping platform that implements HTN. A deployment of HTNMotes was conducted and evaluated at the TTCI facility in Pueblo, Colorado in the US. The results from our field tests confirm that this approach is an order of magnitude better in performance compared to solutions based on ZigBee alone. In such an application, energy considerations represent a key challenge. These sensors have no readily available continuous energy source, but are expected to operate for years in harsh conditions. Energy harvesting — from vibrations, temperature differences, or solar radiation — may provide a potential solution to the energy scarcity. This also mandates that the HTNMote hardware and HTN protocol both be as energy efficient as possible. In this paper we present detailed measurements of the energy consumed by the HTNMote in various operational situations that are encountered during their operation onboard freight railcars. We introduce an energy consumption model based on our analysis of the measurements. This model demonstrates the energy-efficiency of the HTNMote implementation.

One of the limiting factors in on-board bearing health monitoring systems is the life of the batteries used to power the system. Thus, any device that can extend the life of the battery, or entirely replace it, is a notable improvement on any currently available systems. Existing on-board monitoring systems, not optimized for low power, are designed to run on approximately 300 mW of power. Current bearing health monitoring systems have proven effective with as few as one reading every four minutes. The environment under which railroad bearings operate is a harsh one, making most forms of energy harvesting very hard to implement. Terfenol-D is a novel and sustainable solution for this problem due to its durable characteristics and strong magnetostriction. A fixture is designed using multiple magnets of ranging magnetization to properly characterize energy harvesting using Terfenol-D. The maximum available power observed during these experiments is about 77 mW under ideal conditions. The generated power is sufficient to run low-power bearing health monitoring systems.

Currently, the onboard applications of many electronic devices that could benefit rail operation are hindered by the lack of availability of electrical power in freight cars. Although the locomotives, of course, have available sources of power, the freight cars usually don’t have any. The systems presented in this paper are meant to provide a solution for distributed power in freight trains. Although ideas like Timken’s generator roller bearing or solar panels exist, the railroads have been slow in adopting them for different reasons, including cost, difficulty of implementation, or limited capabilities. The solutions presented in this paper are vibration-based electromechanical energy harvesting systems. With size and shape similar to conventional shock absorbers, these devices are designed to be placed in parallel with the suspension elements, possibility inside the coil spring, maximizing underutilized space. As the train goes down the track, the suspension will accommodate the imperfections and its relative displacement will be used as the input for the harvesting systems. The first prototype generation used a linear generator, with the advantage of no need for a mechanical transformation of the input. They have proven that they could work but present some limitations in terms of power and efficiency. The second generation of prototypes is built around a rotating generator. The linear input motion is transformed into rotation by a ball screw. The possibility of including a gearbox to increase the speed is the key to greatly improve performances. The latest built prototype has shown during lab tests that it is capable of providing up to 75W RMS with displacements and velocities that resemble the relative motion across a vehicle suspension.

As the story goes, a wise railroad man once declared: Power is the king! Although he was referring to the motive power that we need to move freight, the same could be said about the availability of electrical power on railcars. This is mainly due to the fact that the onboard applications of many smart devices that can add to the efficiency of rail operation are hindered by the lack of availability of electrical power. In this paper, innovative solutions to provide a distributed source of electrical power for railroad onboard applications are presented. In a suspension of a railcar, mechanical energy is dissipated in dampers or wedges and, therefore, wasted in heat. Meant to be placed inside the coil springs of the suspension, the proposed vibration-based electromechanical systems are designed to harvest part of that wasted energy and turn it into useful electrical power. The energy produced is then conditioned and stored in commonly available batteries. The possibility of realizing the mechanical-to-electrical power conversion without any prior transformation of the mechanical input is first investigated. This aims to avoid inherent losses induced in such processes. The prototypes use an arrangement of magnets that moves linearly with the suspension inside one or several coils. The variable magnetic field thus created generates a voltage. The prototypes prove that it is possible to use a translational generator to provide enough power for recharging batteries under conditions commonly experienced in railcar operation. The second generation of prototypes investigates the idea of transforming the input translation from the suspension into rotation and then using a rotary generator. The advantage of developing such a concept is the possibility of including a gearbox to increase the generator speed of rotation. Maintaining high shaft speed is the key to harvest more power and reach higher efficiencies. The output power is improved even more by adding a mechanism that rotates the generator shaft in the same direction independently of how the suspension is moving (jounce or rebound). Both designs prove they can recharge batteries under commonly experienced conditions. But although the linear generator shows some limitations in terms of power (up to a few watts RMS), the rotary generator design demonstrates significantly higher efficiency and greater output power (40Watts RMS with a sine wave input of ±0.75in at 1Hz). The amount of generated power can be augmented by increasing the amplitude and/or the frequency of the input, customizing the generator, and bringing new improvements to the mechanical part of the system.

Railroad freight car safety and maintenance cost is directly related to knowledge of the actual braking force provided by a brake shoe. If the brake force is too low, safety is at risk. If the brake shoe is replaced before the end of it’s lifetime to ensure safety, maintenance and thus operating costs are increased. Through Federal Railroad Administration (FRA) funding under the Department of Transportation (DoT) Small Business Innovative Research (SBIR) Program, Mide´ Technology Corporation is developing a self-powered brake force measurement system applicable to freight trains. The system provides its own power using Mide´’s proprietary piezoelectric energy harvester that harnesses energy from structural vibrations inherent on all trains. The brake force is measured using specialty high temperature strain gages installed directly on the brake beam.