Road-rail vehicles built on traditional vehicle chassis can only switch operation modes at particular areas such as level crossings, thus limiting the working scope and efficiency of routine railway inspection and maintenance. This paper proposes a novel tracked chassis for the road-rail vehicle with a multi-cylinder hydropneumatic suspension system, which can better adapt to rough terrains and enhance the vehicle ride performance. Based on this hydropneumatic suspension design, the single-cylinder mathematical model is derived and validated by experimental data. An in-plane multi-body dynamics (MBD) model and road model are established, combined with the hydropneumatic suspension model, including the LuGre friction force. Virtual tests are conducted to investigate the effects of different initial gas volumes, varied diameters and damping pipe lengths on the ride performance. The results indicate that improper damping pipe diameter and charge gas volume will deteriorate the ride performance, which provides a useful reference for the optimization design and control of the hydropneumatic system.

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This paper introduces a new form of energy-harvesting suspension that is integrated in a hydraulically interconnected suspension (HIS) system. The combined energy-harvesting and hydraulic interconnection features provide improved energy efficiency and vehicle dynamics performance. A half car model and a full car model are developed to validate the effectiveness of this design. Different dynamic input scenarios are used for model simulation, which includes single-wheel sinusoidal input, two-wheel sinusoidal input and double lane change test. The system performs better than a conventional suspension system in rolling dynamics in the cases of the single-wheel road input and double lane change test. The heaving dynamics is dependent on the frequency of the road input. The energy harvesting can generate up to 421 w at 4 Hz and 40 mm (peak to peak) road input.

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This paper introduces a novel energy-harvesting hydraulically interconnected suspension (EH-HIS) to improve the riding comfort and road handling performance for off-road vehicles while harvesting the vibration energy traditionally dissipated into heat by the oil shock absorbers. To understand the system, we built a model of the off-road vehicle equipped with the EH-HIS and conducted the performance analysis. The system model is established based on the pressure drop principle and validated by commercial simulation software AMESim. The damping characteristic and energy harvesting performance have been investigated based on the mathematical suspension model. Further, a thorough analysis is implemented to compare the dynamic responses of the vehicle equipped with the traditional suspension and EH-HIS under different driving speeds and road classes. Results show that the EH-HIS system can provide tunable asymmetric damping from 3134 Ns/ to 7558 Ns/m, which covers most of the damping range of the off-road vehicles. The average regenerative power of the half EH-HIS system reaches 438 watts, and the corresponding hydraulic efficiency reaches 19%, at a vibration input of 2 Hz frequency and 30 mm amplitude. The ride analysis shows that the vehicle equipped with the EH-HIS system on the D class road has good handling stability and better ride comfort over the traditional suspension.