The critical hitch angle for jackknife avoidance during slow backing up of vehicle–trailer systems

The authors set out to answer the question: At what hitch angle does it become impossible for a vehicle and trailer to continue to backing up without getting into a jackknife? Jackknifing during backing up of trailers occurs when the hitch angle increases to a point such that the vehicle and trailer fold together about the hitch point like a jackknife. If the backward motion is continued, the jackknife effect progressively worsens, until the vehicle and trailer are in physical contact with each other. Jackknifing can result in traffic disruptions and wasted time, and can potentially cause damage or personal injury. The goal is to analytically determine the ‘critical hitch angle’ (θcr), the hitch angle threshold beyond which a continued reverse motion causes an inescapable jackknifing. In this paper, the authors provide a formal definition of θcr for slow backing up of vehicle–trailer systems on a level solid surface, beyond which the vehicle must stop backing up and revert to forward motion in order to escape from jackknifing. The critical hitch angle is sub-categorised into Absolute (θcr, a) and Directional (θcr, d) critical hitch angles depending on the operating constraints and vehicle steering objectives. One solution for θcr is posed as a numerical solution to the steady-state conditions of the dynamic equations. The effects of such hitch angle limitations are demonstrated through simulation. Also, a warning system making use of the θcr is proposed. Such warning systems can assist drivers in avoiding jackknifing while backing up a vehicle–trailer system.


  • English

Media Info

  • Media Type: Web
  • Features: Figures; References; Tables;
  • Pagination: pp 992-1015
  • Serial:

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Filing Info

  • Accession Number: 01531066
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 1 2014 3:00PM