April 2019

BY Frank Massey P icking up from my topic and opinions on autonomous vehicle control last month I think it reasonable to explore the very technology our safety is to be placed. When considering the most challenging aspect of autonomous vehicle control, we must look to steering and stability correction. My references are limited to the Volkswagen Group, however most manufacturers now share similar drivetrain and chassis technology. Steering assist These systems have evolved over many years in what I term modular development. Steering assist is such a system. Steering assist is directly proportional to driver input force, the steering torque sensor g269 detects rotation, the steering angle sensor g85 provides angle and rotation acceleration. Responding to this data the control module j500 calculates the required assistance from the power steering assist motor v187. When parking, a low or zero vehicle speed combined with a rapid steering input provides maximum assistance. During driving additional data relating to environmental conditions, urban or motorway, modifies the appropriate assistance. One of the first problems to overcome was return to neutral or zero steering angle. This is activated with a reduction in force on the torsion bar, whereby the rate of return is also a function of environmental influences. The dual steering angle sensor is comprised of a LED and photo electric diode. The steering torque sensor operates on the magnetic resistance principle. Failure results in a gradual reduction in assistance. The asynchronous brushless motor provides up to 4nm of assistance. Once again emphasis should be directed to programming and adaptive correction via e serial platform. Stability & proximity When introducing vehicle stability dynamics, even more data is required: An accelerometer as well as yaw and pitch sensors will complement existing input requirements. Enhanced and shared functionality with ABS enables the 24 AFTERMARKET APRIL 2019 TECHNICAL www.aftermarketonline.net STEERING YOU RIGHT? Frank Massey continues his look at the thorny issue of autonomous control, focusing on steering and stability correction leading to autonomy