Improvement in Vehicle Handling through Optimization of Steering System Compliance 2012-01-1938

Recent infrastructural developments and emerging automotive market in India has given an impetus to the transportation industry and has led to high end research activities in synchronization with growing customer demands and competition especially in last decade. Since average speeds in India has gone up from 50 kmph in the year 2000 to almost 100 kmph in 2011, even the Light Commercial Vehicles (5 to 9.6T) are gradually experiencing a shift from low speed to high speed goods carrier. These new age vehicles are developed with a driver centric outlook towards safety and comfort. They are better optimized and equipped to the changing needs of the consumer and road conditions.

Increase in vehicle speed poses many challenges in terms of occupant safety and control. In view of this, refinement of different vehicle handling parameters with respect to steering system compliance becomes far more critical. Present work discusses how the steering system compliance influences vehicle handling performance in Light Commercial Vehicles especially with respect to the vehicle response to various kinds of possible driver inputs. During development process, a lot of scope was observed to improve steering system response of prototype vehicles. It was observed during investigation that due to higher deflection losses in the steering system the vehicle behavior towards steering inputs was erratic and led to low driving confidence.

Proposed work focuses primarily on investigating the effect of improving steering compliance on torque feedback, on-center feel, and vehicle response to various driver transient inputs. Objective and subjective evaluations have been carried out on the test vehicle and results are correlated for confirmation. Design targets were set for overall steering system compliance in comparison to world class products. With improved steering system compliance 20-25% improvement in handling performance was achieved. The results discussed here may easily be extended to similar class of vehicles with comparable design of steering system.