Influence Of Freeway Plane Alignment On Driver’s Perception Speed

Driving on flat curve roads needs to complete driving tasks such as speed adjustment and lane control at the same time,which places higher requirements on the driver’s information perception,judgment,decision-making,and manipulation.At present,the accident rate and severity of accidents on flat curve road sections are more prominent,which is also a key concern of road operation managers.Overspeed is the main cause of accidents on flat curve roads.Among the many causes of overspeed,the deviation of the driver’s speed perception is an important factor causing overspeed.If we can find out the regularity of the influence of the flat curve on the driver’s speed perception,we can put forward targeted speed management and control measures to improve traffic safety.Based on this,it is of great practical significance to study the effect of expressway plane alignment on driver’s speed perception.Based on extensive reading of relevant literature at home and abroad,the thesis analyzes the relevant theories of motion perception,elaborate on the core points of optical flow theory,contrast,space-time frequency and visual multi-channel theory.Although these theories are proposed for the general population,But its basic arguments can be used as a theoretical basis for analyzing the driver’s speed perception,especially the edge rate in the space-time frequency has a guiding significance for explaining the effect of the radius of the circular curve on the speed.Using UC-win/Road software,25 road scenes with different radii and different linear combinations were constructed.A six-degrees-of-freedom cockpit was used to conduct simulated driving experiments.During the simulation experiment,the "interrogation method" was used to obtain the driver’s different curves.The subjective perception speed of feature points,the simulator built-in ECO software records the actual speed of the whole journey.By comparing and analyzing the driver’s subjective perceived speed and actual speed,the results show that:(1)The driver tends to underestimate more vehicle speeds near the corner,and the degree of underestimation will gradually decrease after entering the curve.(2)The curve segment has a certain improvement effect on the perception of vehicle speed.As the radius of the circular curve increases,the improvement effect gradually weakens.(3)There is a superposition effect on the speed sensing in the same direction,reverse direction and S curve,that is,the speed sensing on the second curve will tend to be accurate on the basis of the first curve.The length of the straight line between the curves and the ratio of the radius of the adjacent curves both affect the changing trend of the perceived speed error.In order to verify the correctness of the indoor simulation experiment results,the actual road sections that are basically consistent with the indoor scene are selected for on-site experiments.The on-board experimenters are asked to obtain the driver’s subjective perception speed at different curve characteristic points,and the USBCAN-OBD converter is used to obtain the vehicle.The actual speed of the whole journey,the analysis results show that the underestimation of the driver’s speed in the outdoor experiment has been alleviated as a whole,but the trend of the speed error of the perception of the speed along the road alignment is basically consistent with the indoor results.The research results of the paper can be used to guide the rational arrangement of speed control facilities and provide a reference for further research on the speed perception mechanism.