The existing research of steering efficiency mainly focuses on the mechanism efficiency of steering system, aiming at designing and optimizing the mechanism of steering system. In the development of assist steering system especially the evaluation of its comfort, the steering efficiency of driver physiological output usually are not considered, because this physiological output is difficult to measure or to estimate, and the objective evaluation of steering comfort therefore cannot be conducted with movement efficiency perspective. In order to take a further step to the objective evaluation of steering comfort, an estimating method for the steering efficiency of the driver was developed based on the research of the relationship between the steering force and muscle activity. First, the steering forces in the steering wheel plane and the electromyography （EMG） signals of the primary muscles were measured. These primary muscles are the muscles in shoulder and upper ann which mainly produced the steering torque, and their functions in steering maneuver were identified previously. Next, based on the multiple regressions of the steering force and EMG signals, both the effective steering force and the total force capacity of driver in steering maneuver were calculated. Finally, the steering efficiency of driver was estimated by means of the estimated effective force and the total force capacity, which represented the information of driver physiological output of the primary muscles. This research develops a novel estimating method for driver steering efficiency of driver physiological output, including the estimation of both steering force and the force capacity of primary muscles with EMG signals, and will benefit to evaluate the steering comfort with an objective perspective.
The existing research of steering comfort mainly focuses on the subjective evaluation,aiming at designing and optimizing the steering system.In the development of steering system,especially the evaluation of steering comfort,the objective evaluation methods considered the kinematic characteristics of driver steering maneuver are not proposed,which means that the objective evaluation of steering cannot be conducted with the evaluation of kinematic characteristics of driver in steering maneuver.In order to propose the objective evaluation methods of steering comfort,the evaluation of steering movement quality of driver is developed on the basis of the study of the kinematic characteristics of steering maneuver.First,the steering motion trajectories of the driver in both comfortable and certain extreme uncomfortable operation conditions are detected using the Vicon motion capture system.The operation conditions are under the restrictions of the vertical height and horizontal distance between steering wheel center and the H-point of driver,and the steering resisting torque else.Next,the movement quality evaluation of driver steering maneuver is assessed using twelve kinds of evaluation indices based on the kinematic analyses of the steering motion trajectories to propose an objective evaluation method.Finally,an integrated discomfort index of steering maneuver is proposed on the basis of the regression analysis of subjective evaluation rating and the movement quality evaluation indices,including the Jerk,Discomfort and Joint Torque indices.The test results show that the proposed integrated discomfort index gives a good fitting with the subjective evaluation of discomfort,which means it can be used to evaluate or predict the discomfort level of steering maneuver.This paper proposes an objective evaluation method of steering comfort based on the movement quality evaluation of driver steering maneuver.
In order to study the function of muscles of driver shoulder during vehicle steering, identification of relations between electromyograph (EMG) activity of 10 shoulder muscles and steering force was performed. The procedure was to perform controlled steering maneuver by right hand in a driving simulator, and based on analyzing the EMG data with steering force in the steering wheel plane, the function was identified. It was found that muscle function depends strongly on both steering rotation and steering torque directions. In clockwise steering, the long head of triceps brachii was the prime mover and an important contributor to clockwise moment, while the sternocostal portion of the pectoralis major, the lateral head of triceps brachii, biceps brachii and teres major were the important stabilizers or fixators. In contrast, in counterclockwise steering, the anterior, middle and posterior deltoid, the clavicular portion of the pectoralis major and infraspinatus were the prime movers and also the important contributors to counterclockwise moment, while the sternocostal portion of the pectoralis major, the lateral head of triceps brachii, biceps brachii and teres major were the important stabilizers or fixators. We conclude that the prime movers are primarily a consequence of steering direction, while the stabilizers or fixators are primarily constant. These results can be used to improve the neuromuscular model and estimate the steering comfort of driver.
LIU YaHuiJI XueWuRYOUHEI HayamaTAKAHIRO MizunoLOU LiMing
