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Field demonstration of the traffic speed deflectometer
Published in Maurizio Crispino, Pavement and Asset Management, 2019
S. Shrestha, S.W. Katicha, G.W. Flintsch
The TSD uses Doppler lasers mounted at a small angle to measure the pavement deflection velocity. Due to its location, mid-way between the loaded trailer axle and the rear axle of the tractor unit, the reference laser is expected to measure very little vertical pavement deflection velocity, and its response can therefore be used to remove the unwanted signals from the six measurement lasers. When accurately calibrated, the TSD measures pavement deflection velocities that do not depend on driving speed. To remove this dependence, the deflection velocity is divided by the instantaneous survey speed to give a measurement of deflection slope. Therefore, the deflection slope is calculated as follows: () S=VvVh
What Is Intermodal Freight Transport?
Published in Lowe FCILT David, Intermodal Freight Transport, 2006
For readers unfamiliar with the technicalities of road vehicles, an articulated vehicle is one comprising a towing vehicle, correctly called the tractive unit, but often referred to as the cab or towing unit or incorrectly as the tractor unit, and a load-carrying trailer, the semi-trailer. They are hitched together with the front end of the semi-trailer superimposed on the rear of the tractive unit (transferring at least 20 per cent of the weight of the load carried by the semi-trailer onto the drawing vehicle, to meet legal requirements), being attached by means of a kingpin on the semi-trailer engaging in a ‘fifth-wheel’ turntable on the tractive unit. When detached from the tractive unit a semi-trailer is supported on forward-mounted landing legs (or landing gear) that are raised or folded away for travel.
Intermodal transport equipment
Published in Jason Monios, Rickard Bergqvist, Intermodal Freight Transport and Logistics, 2017
Rickard Bergqvist, Jason Monios
A semi-trailer connects to a road tractor unit but it is also equipped with legs that can be lowered to support the trailer when it is uncoupled. The entire unit is called an articulated lorry or articulated truck, as opposed to a rigid vehicle that is not able to pivot on the joint. Semi-trailers with two trailer units are called B-doubles or road trains. Like swap bodies, semi-trailers can be rigid or curtain sided or whatever formation is suitable for the cargo. Road vehicles can also be carried on rail wagons in their entirety (as in the Channel Tunnel). This is referred to as ‘piggyback’, and is less common than utilising a container (see Lowe, 2005; Woxenius and Bergqvist, 2011) (Figure 2.6).
Model predictive-based tractor-trailer stabilisation using differential braking with experimental verification
Published in Vehicle System Dynamics, 2021
Mehdi Abroshan, Reza Hajiloo, Ehsan Hashemi, Amir Khajepour
Trailer differential braking (TRDB) is another control action used to stabilise a tractor-trailer vehicle. In the literature, the main objective of TRDB is to generate a corrective yaw moment on the trailer unit to align it with the tractor unit e.g. reducing articulation angle [8,9,23]. Sun et al. designed a trailer differential braking controller using fuzzy logic [10]. The results showed that differential braking on the trailer unit is able to prevent yaw and roll instabilities effectively. It was also proposed that a threshold can be identified for the actuator activation using the non-linear stability analysis. Fernández et al. [23] and Shamim et al. [8] used different controllers including an error based controller and a linear quadratic regulator. They also confirmed that TRDB is helpful in stabilising a tractor-trailer vehicle.
Robust lateral control of long-combination vehicles under moments of inertia and tyre cornering stiffness uncertainties
Published in Vehicle System Dynamics, 2019
Maliheh Sadeghi Kati, Hakan Köroğlu, Jonas Fredriksson
The SLC manoeuvers are simulated at a fixed longitudinal velocity of with steering input frequencies ranging from 0.05 to 1 Hz. To facilitate a fair comparative evaluation, the amplitude of the driver steering input is adjusted in each case in a way to have a peak lateral acceleration of 1.5 m s−2 at the first axle of the tractor unit (i.e. peak m s−2). This is done mainly to ensure that the tyre forces remain mostly in the linear region of the tyre force curve. However, this level of lateral acceleration was also considered as a reasonable value for investigating heavy vehicles with a lateral acceleration RAt of 2 or higher. For instance for a heavy vehicle with a lateral acceleration RAt of 2 and a peak of m s−2, the peak lateral acceleration of the last unit will be 3 m s−2, which is less than the rollover threshold level of 3.5 m s−2 recommended according to Australian Performance Based Standard [41].
Estimation of trailer off-tracking using visual odometry
Published in Vehicle System Dynamics, 2019
Christopher de Saxe, David Cebon
The ability to measure trailer off-tracking, in a manner which is independent of friction conditions and requires no parameter data or sensor measurements from the tractor unit, would improve the commercial prospects of path-following trailer steering systems. Furthermore, such a solution could find application in other areas requiring a versatile means of measuring trailer off-tracking. For example, it could be used to measure the swept path performance of heavy vehicles for certification with performance-based regulatory schemes, such as those in Australia and South Africa [4,5].