Tyre curve estimation in slip-controlled braking

Progress in reducing actuator delays in pneumatic brake systems creates an opportunity for advanced anti-lock braking algorithms to be used on heavy goods vehicles. However, these algorithms require knowledge of variables that are impractical to measure directly. This paper introduces a braking force observer and road surface identification algorithms to support a sliding-mode slip controller for air-braked heavy vehicles. Both the force observer and the slip controller are shown to operate robustly under a variety of conditions in quarter-car simulations. A non-linear least-squares algorithm was found to be capable of performing regressions on all the parameters of the tyre model from the University of Michigan Transportation Research Institute when used ‘in the loop’ with the controller and the observer. A recursive least-squares algorithm that is less computationally expensive than the non-linear algorithm was also investigated but gave only reasonable estimates of the tyre model parameters on high-friction smooth roads. The authors would like to thank the members of the Cambridge Vehicle Dynamics Consortium (CVDC), and the Gates Cambridge Trust for their parts in funding this work.This is the author accepted manuscript. The final version is available from Sage via http://dx.doi.org/10.1177/095440701558593

Sideslip estimation for articulated heavy vehicles at the limits of adhesion

Various active safety systems proposed for articulated heavy goods vehicles (HGVs) require an accurate estimate of vehicle sideslip angle. However in contrast to passenger cars, there has been minimal published research on sideslip estimation for articulated HGVs. State-of-the-art observers, which rely on linear vehicle models, perform poorly when manoeuvring near the limits of tyre adhesion. This paper investigates three nonlinear Kalman filters (KFs) for estimating the tractor sideslip angle of a tractor–semitrailer. These are compared to the current state-of-the-art, through computer simulations and vehicle test data. An unscented KF using a 5 degrees-of-freedom single-track vehicle model with linear adaptive tyres is found to substantially outperform the state-of-the-art linear KF across a range of test manoeuvres on different surfaces, both at constant speed and during emergency braking. Robustness of the observer to parameter uncertainty is also demonstrated.Engineering and Physical Sciences Research Council, Cambridge Vehicle Dynamics Consortiu

Field Testing of a Cyclist Collision Avoidance System for Heavy Goods Vehicles

This research focused on preventing collisions between cyclists and heavy goods vehicles (HGVs). A collision avoidance system, designed to avoid side-to-side collisions between HGVs and cyclists, is proposed. The cyclist’s motion relative to the HGV is measured with an array of ultrasonic sensors. The detected distances from ultrasonic sensors are processed in real time to construct a smooth trajectory for the cyclist. The controller assumes constant acceleration and constant yaw rate for both the HGV and the cyclist and extrapolates the relative motion forward in time. The HGVs' brakes are engaged if a collision is predicted. A prototype system was built and fitted onto a test truck. The proposed collision avoidance system was tested in real time and proved to be effective within certain speed ranges.The authors thank the support of the Cambridge Vehicle Dynamics Consortium, whose member at the time of writing are: Anthony Best Dynamics, Camcon, Cambridge University, Denby Transport, Firestone Goodyear, Haldex, Laing O’Rourke, MIRA, SDC Trailers, SIMPACK, Tridec, Tinsley Bridge, Wincanton and Volvo Trucks. Special thanks go to Anthony Best Dynamics and Laing O'Rourke for proving essential testing equipment. Thanks also go to Dr Richard Roebuck, Dr Leon Henderson and Ms Amy Rimmer for their assistance with the testing. The authors also would like to thanks China Scholarship Council and Cambridge Trusts for their contribution to the research.This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/TVT.2016.253880

Theory and practice of reversing control on multiply-articulated vehicles

A path-tracking controller is presented for automating the reversing of multiply-articulated vehicles. This uses a state feedback approach and steers the wheels of the front axle to ensure that the rearmost vehicle unit tracks a specified path. Linear closed-loop analysis is performed and shows that the controller is stable for vehicles with up to six trailers. The controller is implemented on three full-size experimental heavy vehicles: a ‘tractor–semitrailer’, a ‘B-double’ vehicle and a ‘B-triple’ vehicle, which have one trailer, two trailers and three trailers respectively. Experimental results are presented and the controller performance is evaluated. All test vehicles were able to track the paths to within 400 mm of the desired path. This research was funded by the Engineering and Physical Sciences Research Council (EPSRC) and Volvo Trucks through an Industrial CASE award. The authors would like to acknowledge Leo Laine and Carl-Johan Hoel from Volvo Trucks for their collaboration and contributions to the research.This is the author accepted manuscript. The final version is available from Sage via http://dx.doi.org/10.1177/095440701559691

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

This paper summarises the measured emergency braking performance of a tri-axle heavy goods vehicle semitrailer fitted with a novel pneumatic slip control braking system developed by the Cambridge Vehicle Dynamics Consortium. Straight-line braking tests were carried out from 40 km/h in order to compare a commercially electro-pneumatic available anti-lock braking system and the Cambridge Vehicle Dynamics Consortium system, which has bi-stable valves coupled with a sliding-mode slip controller. On average, the Cambridge Vehicle Dynamics Consortium system reduced the stopping distance and the air use by 15% and 22% respectively compared with those for the conventional anti-lock braking system. The most significant improvements were seen on a wet basalt-tile surface (with similar friction properties to ice) where the stopping distance and the air use were improved by 17% and 30% respectively. A third performance metric, namely the mean absolute slip error, is introduced to quantify the ability of each braking system to track a wheel slip demand. Using this metric, the bi-stable valve system is shown to improve the wheel slip demand tracking by 62% compared with that of the conventional anti-lock braking system. This improvement potentially allows more accurate control of the wheel forces during extreme manoeuvres, providing scope for the future development of advanced stability control systems. This work was supported by Haldex Brake Products Ltd, the New Zealand Tertiary Education Commission and the Cambridge Vehicle Dynamics Consortium (CVDC).This is the author accepted manuscript. The final version is available from Sage via http://dx.doi.org/10.1177/095440701560480

Relationship between heavy vehicle speed limit and fleet fuel consumption on minor roads

This paper investigates the traffic-related effects of a proposal to increase the speed limit from 40 mile/h to 50 mile/h, for heavy goods vehicles greater than 7.5 tonnes, on single carriageway roads. A ‘microscopic’ single carriageway traffic simulation is developed by combining the ‘enhanced intelligent driver model’ with a single carriageway gap-acceptance passing model. Fuel consumption estimates are made using engine characteristic maps and a ‘fuel optimal’ gear selection scheme, where vehicle trajectories from the traffic simulations are taken as input drive-cycles. Traffic congestion and fleet fuel consumption are specifically addressed, though implications regarding passing behaviour and traffic safety are also noted. Results indicate that the proposed 50 mile/h heavy goods vehicles speed limit would reduce traffic congestion by over 37% and increase fleet fuel consumption by approximately 0.5 L/100 km. The authors would like to thank Justin Bishop and Niall Martin of Cambridge University Engineering Department for providing valuable data. The authors would also like to thank Rachael Dillon of Freight Transport Association for suggesting the project. This work was supported in part by the Centre for Sustainable Road Freight (SRF) and the Engineering and Physical Sciences Research Council (EPSRC) through Grant Ref EP/K00915X/1. At the time of writing, the members of the SRF were: Coca-Cola Enterprises, Denby Transport, DHL, Freight Transport Association, Haldex Brake Products, Goodyear Tires, John Lewis/Waitrose, Laing O’Rourke, Optrak, SDC Trailers, Tesco, Volvo Trucks, Warburtons, Wincanton.This is the accepted manuscript for a paper published in the Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, DOI: 10.1177/0954406215573038

A novel HLA-B18 restricted CD8+ T cell epitope is efficiently cross-presented by dendritic cells from soluble tumor antigen

NY-ESO-1 has been a major target of many immunotherapy trials because it is expressed by various cancers and is highly immunogenic. In this study, we have identified a novel HLA-B*1801-restricted CD8<sup>+</sup>T cell epitope, NY-ESO-1<sub>88–96</sub> (LEFYLAMPF) and compared its direct- and cross-presentation to that of the reported NY-ESO-1<sub>157–165</sub> epitope restricted to HLA-A*0201. Although both epitopes were readily cross-presented by DCs exposed to various forms of full-length NY-ESO-1 antigen, remarkably NY-ESO-1<sub>88–96</sub> is much more efficiently cross-presented from the soluble form, than NY-ESO-1<sub>157–165</sub>. On the other hand, NY-ESO-1<sub>157–165</sub> is efficiently presented by NY-ESO-1-expressing tumor cells and its presentation was not enhanced by IFN-γ treatment, which induced immunoproteasome as demonstrated by Western blots and functionally a decreased presentation of Melan A<sub>26–35</sub>; whereas NY-ESO-1<sub>88–96</sub> was very inefficiently presented by the same tumor cell lines, except for one that expressed high level of immunoproteasome. It was only presented when the tumor cells were first IFN-γ treated, followed by infection with recombinant vaccinia virus encoding NY-ESO-1, which dramatically increased NY-ESO-1 expression. These data indicate that the presentation of NY-ESO-1<sub>88–96</sub> is immunoproteasome dependent. Furthermore, a survey was conducted on multiple samples collected from HLA-B18+ melanoma patients. Surprisingly, all the detectable responses to NY-ESO-1<sub>88–96</sub> from patients, including those who received NY-ESO-1 ISCOMATRIX™ vaccine were induced spontaneously. Taken together, these results imply that some epitopes can be inefficiently presented by tumor cells although the corresponding CD8<sup>+</sup>T cell responses are efficiently primed in vivo by DCs cross-presenting these epitopes. The potential implications for cancer vaccine strategies are further discussed

Path-following control based on ground-watching navigation

This paper discusses the path-following performance of actively-steered articulated vehicles based on measurement signals from two ‘ground-watching’ navigation systems (GWNS). The ground-watching navigation systems are described. These use high-speed USB-3 cameras and an image processing computer to measure and calculate off-tracking distance for a path-following steering controller. Full-scale field tests are performed using an experimental articulated vehicle, tested under both open-loop and closed-loop conditions. Off-tracking distance at the rear camera with respect to the front camera is controlled to be less than 0.1m for tests with both GWNSs

Camera-Based Articulation Angle Sensing for Heavy Goods Vehicles

Articulation angle sensing is an essential component of manoeuvrability and stability control systems for articulated heavy goods vehicles, particularly long combination vehicles. Existing solutions to this sensing task are limited by reliance on trailer modifications or information or by measurement accuracy, or both, restricting commercial adoption. In this paper we present a purely tractor-based sensor concept comprising a rear-facing camera and the parallel tracking and mapping (PTAM) image processing algorithm. The system requires no prior knowledge of or modifications to the trailer, is compatible with planar and non-planar trailer shapes, and with multiply-articulated vehicle combinations. The system is validated in full-scale vehicle tests on both a tractor semi-trailer combination and a truck and full-trailer combination, demonstrating robust performance in a number of conditions, including trailers with non-planar geometry and with minimal visual features. Average RMS measurement errors of 1.19, 1.03 and 1.53 degrees were demonstrated for the semi-trailer and full-trailer (drawbar and semi-trailer) respectively. This compares favourably with the state-of-the-art in the published literature. A number of improvements are proposed for future development based on the observations in this research.This work was funded by the Cambridge Commonwealth, European and International Trust (CCEIT), the Council for Scientific and Industrial Research (CSIR, South Africa), and the Cambridge Vehicle Dynamics Consortium (CVDC). At the time of writing the Consortium consisted of the University of Cambridge with the following partners from the heavy vehicle industry: Anthony Best Dynamics, Camcon, Denby Transport, Firestone Industrial Products, Goodyear, Haldex, MIRA, SDC Trailers, Tinsley Bridge, Tridec, Volvo Trucks, and Wincanton