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This paper reviews the state-of-the-art control schemes for enhancing the lateral stability of car-trailer (CT) combinations. Various studies have been conducted on lateral stability control of single-unit vehicles, e.g., cars. However, much less attention has been paid to lateral stability control of multi-unit vehicles, e.g., CT, which usually exhibit poor manoeuvrability in curved-path negotiations and low lateral stability under high-speed evasive manoeuvres. The low lateral stability may lead to unstable motion modes, e.g., trailer-sway and jackknifing, causing severe accidents. To improve the lateral stability, various control schemes were designed considering relevant performance measures and evaluated using either numerical simulations or testing methods. Thus, the topics surveyed in this paper include: directional performance measures, evaluation methods, important parameters affecting the directional performance, and active control approaches for CT combinations. Important control schemes are emphasised and their features discussed and analysed. As a result of the overview, future research efforts are identified.

This paper proposes the application of an automated frequency response measuring (AFRM) technique to the lateral dynamic analysis in the frequency-domain for articulated heavy vehicles (AHVs). The AFRM method can be used to automatically acquire the frequency response function of the rearward amplification (RWA) ratio, an important performance measure of the lateral stability of AHVs. A numerical simulation in the time-domain can only achieve the corresponding dynamic response at a specified frequency; to achieve dynamic responses over a frequency band, numerous simulations at various frequencies have to be conducted, and this is a tedious and time consuming process. The RWA measure is frequency-dependent, and the measure in the frequency-domain is of critical importance for the stability evaluation and design synthesis of AHVs. The feasibility and effectiveness of the proposed method is examined using numerical simulations of a tractor/semitrailer combination represented by a linear and a nonlinear AHV model.

This paper presents an automated design synthesis method for multi-trailer articulated heavy vehicles (MTAHVs) to coordinate the trade-off between the manoeuvrability and stability. Conventionally, the design synthesis of MTAHVs is based on trial and error approaches. This is difficult, time-consuming and tedious. To tackle this problem, a design method is proposed. The method has the following features: 1) vehicle modelling, performance evaluation, and design selection are implemented by computers; 2) a MTAHV model is introduced in the design optimisation; 3) in the closed-loop simulation, testing manoeuvres are emulated such that a driver model 'drives' the virtual MTAHV to follow a predefined trajectory. To test the method, the combination of a tractor and two semitrailers are optimised. It is indicated that the conflicting criteria of manoeuvrability and stability can be simultaneously improved. The approach may identify desired design variables and predict performance envelopes in early design stages of MTAHVs.