Designing and testing an advanced pneumatic braking system for heavy vehicles

Abstract

Heavy goods vehicles exhibit poor braking performance in emergency situations when compared to other vehicles. Part of the problem is caused by sluggish pneumatic brake actuators, which limit the control bandwidth of their antilock braking systems. In addition, heuristic control algorithms are used that do not achieve the maximum braking force throughout the stop. In this article, a novel braking system is introduced for pneumatically braked heavy goods vehicles. The conventional brake actuators are improved by placing high-bandwidth, binary-actuated valves directly on the brake chambers. A made-for-purpose valve is described. It achieves a switching delay of 3–4 ms in tests, which is an order of magnitude faster than solenoids in conventional anti-lock braking systems. The heuristic braking control algorithms are replaced with a wheel slip regulator based on sliding mode control. The combined actuator and slip controller are shown to reduce stopping distances on smooth and rough, high friction ( μ = 0.9) surfaces by 10% and 27% respectively in hardware-in-the-loop tests compared with conventional ABS. On smooth and rough, low friction ( μ = 0.2) surfaces, stopping distances are reduced by 23% and 25%, respectively. Moreover, the overall air reservoir size required on a heavy goods vehicle is governed by its air usage during an anti-lock braking stop on a low friction, smooth surface. The 37% reduction in air usage observed in hardware-in-the-loop tests on this surface therefore represents the potential reduction in reservoir size that could be achieved by the new system.

Sideslip estimation for articulated heavy vehicles at the limits of adhesion

“…[44] LAEKF, LAUKF and FUKF were considered. Each of these three nonlinear observers were based around the same underlying vehicle model as Cheng and Cebon's KF, but augmented with either an adaptive or nonlinear tyre model in order to improve performance at the limits of tyre adhesion.…”

An investigation of the effects of pneumatic actuator design on slip control for heavy vehicles

“…In addition, HGV ABS has been observed to cause large fluctuations in wheel slip [10]. When considering a typical wheel slip-braking force curve (Figure 2), the large fluctuations mean the wheels spend much of their time in suboptimal regions of the slip-friction curve, where braking force is reduced [10].…”

“…As a consequence of the various pneumatic delays, conventional HGV ABS has a limited bandwidth: cycling at frequencies of 1.25-2 Hz, when compared with passenger car ABS, which cycles at frequencies closer to 6-8 Hz [8,9]. In addition, HGV ABS has been observed to cause large fluctuations in wheel slip [10]. When considering a typical wheel slip-braking force curve (Figure 2), the large fluctuations mean the wheels spend much of their time in suboptimal regions of the slip-friction curve, where braking force is reduced [10].…”

“…It has been shown in [10][11][12] that actuation delays in heavy vehicles could be reduced by an order of magnitude from the nominal 40 ms by placing fast pneumatic valves directly on brake Downloaded by [University of Saskatchewan Library] at 01:05 15 October 2012 chambers. Such reductions in actuation delay would allow advanced braking control methods to be used on pneumatically braked vehicles.…”

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].…”