Full-scale testing of a novel slip control braking system for heavy vehicles

Abstract

This paper summarises the measured emergency braking performance of a tri-axle heavy goods vehicle (HGV) semitrailer fitted with a novel pneumatic slip-control braking system developed by the Cambridge Vehicle Dynamics Consortium (CVDC). Straight-line braking tests were carried out from 40km/h in order to compare a commercially available electropneumatic HGV trailer ABS system and the CVDC system, which has bi-stable valves coupled with a sliding mode slip controller. On average, the CVDC system reduced stopping distance and air use by 15% and 22% respectively compared to conventional ABS. The most significant improvements were seen on a wet basalt tile surface (with similar friction properties to ice) where stopping distance and air use were improved by 17% and 30% respectively. A third performance metric, mean absolute slip error (MSE), is introduced to quantify each braking system's ability to track a wheel slip demand. Using this metric, the bistable valve system is shown to improve wheel slip demand tracking by 62% compared to conventional ABS. This improvement potentially allows more accurate control of wheel forces during extreme manoeuvres, providing scope for the future development of advanced stability control systems.

Combined emergency braking and turning of articulated heavy vehicles

“…Although this idealised performance could never be completely realised in the presence of disturbances, noise, uncertain parameters and bandwidth limits, it is a reasonable approximation of current high-bandwidth prototype systems. Accurate regulation of slip has been demonstrated in real vehicle tests with the CVDC's prototype system [11,22] and various methods have been proposed by which to estimate the optimum slip value for braking [10,23]. As SC technology continues to improve, the idealised SC model should become an ever more accurate approximation.…”

“…'Slip control' (SC) braking strategies have been proposed for both HGVs and passenger cars [1][2][3][4][5][6][7][8][9][10][11]. SC shortens emergency stopping distances by accurately regulating longitudinal wheel slip to the point of maximum braking force.…”

“…For HGVs the stopping distance reduction can be substantial. The Cambridge Vehicle Dynamics Consortium (CVDC), for example, demonstrated up to 19% straight-line stopping distance reductions on low friction surfaces, relative to conventional EBS, using a prototype pneumatic SC system on a tractor-semitrailer [11,12].…”

Sideslip estimation for articulated heavy vehicles at the limits of adhesion

“…Both vehicle units were equipped with the Cambridge Vehicle Dynamics Consortium's (CVDC's) prototype pneumatic slip control braking system, details of which can be found in [35,36]. During emergency braking, this system accurately regulates the slip of each individual wheel to achieve maximum braking force.…”

An Experimental Study on Hysteresis Characteristics of a Pneumatic Braking System for a Multi-Axle Heavy Vehicle in Emergency Braking Situations

“…In this case, scholars have undertaken a large amount of related research recently, and various technologies have been proposed and successfully implemented for better pneumatic braking performance of MHVs, including sliding mode controllers [5][6][7], nonlinear model predictive controllers [8], indirect adaptive robust controllers (IARC) [9], and novel braking actuators [10]. Nevertheless, the braking performance of MHV is still much poorer than that of the passenger car [7].…”