Four Wheel Steering
2009 Assessment H.N. Steering and Suspension Systems D67G04 (2510259)
By, Dave Masih HNC Automotive Engineering
Introduction Four wheel steering was created to aid in stability, high speed manoeuvring and to ease parking. There have been many four wheel steering systems introduced by various manufacturers such as Nissan with their HICAS and SUPER HICAS system, General Motors with Quadrasteer and the Honda system introduced on the Prelude. The four wheel steering works by inducing an angle change at the rear wheels, the angle is determined by the steering angle sensor which varies due to driver input and the velocity the vehicle is travelling at. In this assessment I will focus on the High Capacity Actively Controlled Steering system used in the Nissan Skyline range. This will also include the operation at high and low speeds of the vehicle; the influence on vehicle stability and handling; the variance on how much rear steer is provided and finally the effects of the vehicles velocity and steering angle on system operation.
Figure 1: This figure above shows, the comparison of Super HICAS to HICAS, two wheel steer and a four wheel steer system. Courtesy of http://www.300zxtt.co.uk/bandbhicas.html 2
System Overview Four wheel steering operates in two phases, in‐phase and contra‐phase. They are activated individually dependent on feedback from various sensors. These two phases are indeed essential to the operative functionality of four wheel steering. The steering assembly comprises of six main components, an electronic control module, pressure control valve, steering angle sensor, vehicle speed sensor, hydraulic actuator and a cut‐off valve. There are many advantages of having four wheel steering, one of which gives you improved stability at high speeds. Another is low speed manoeuvrability,
By, Dave Masih HNC Automotive Engineering
Introduction Four wheel steering was created to aid in stability, high speed manoeuvring and to ease parking. There have been many four wheel steering systems introduced by various manufacturers such as Nissan with their HICAS and SUPER HICAS system, General Motors with Quadrasteer and the Honda system introduced on the Prelude. The four wheel steering works by inducing an angle change at the rear wheels, the angle is determined by the steering angle sensor which varies due to driver input and the velocity the vehicle is travelling at. In this assessment I will focus on the High Capacity Actively Controlled Steering system used in the Nissan Skyline range. This will also include the operation at high and low speeds of the vehicle; the influence on vehicle stability and handling; the variance on how much rear steer is provided and finally the effects of the vehicles velocity and steering angle on system operation.
Figure 1: This figure above shows, the comparison of Super HICAS to HICAS, two wheel steer and a four wheel steer system. Courtesy of http://www.300zxtt.co.uk/bandbhicas.html 2
System Overview Four wheel steering operates in two phases, in‐phase and contra‐phase. They are activated individually dependent on feedback from various sensors. These two phases are indeed essential to the operative functionality of four wheel steering. The steering assembly comprises of six main components, an electronic control module, pressure control valve, steering angle sensor, vehicle speed sensor, hydraulic actuator and a cut‐off valve. There are many advantages of having four wheel steering, one of which gives you improved stability at high speeds. Another is low speed manoeuvrability,
References: Five out of six of the references were courtesy of the following websites: Figure 1: http://www.300zxtt.co.uk/bandbhicas.html Figure 2: http://www.240edge.com/basics/super‐hicas.html Figure 3: http://books.google.com/books?id=I90NpNQUzJ4C&pg=PP1&dq=light+and+heavy+vehicle+technology# v=onepage&q=four%20wheel%20steer&f=false Figure 4: http://www.zcargarage.com/photo‐gallery/zcg‐nissan‐skyline‐gt‐r.htm Figure 5: http://www.ilovegtr.com/r32net/fig/know/hicas2.jpg Figure 6: I personally created this illustration. 8