*4.1. Apparatus*

Considering that the actual vehicle obstacle avoidance experiment possesses certain risks, this study employed a driving simulator to perform the obstacle avoidance experiment. The driving simulator is a modified simulation technology that combines pure digital simulation with field test. The vehicle, driving field, and various types of sensors are constructed by a digital method to reproduce the real driving scene and satisfy various requirements of the vehicle test and development. The driving simulator tests are characterized by low cost, high e fficiency, repeatability, and low risk coe fficient. The driving simulator used in this work is presented in Figure 7. The simulator mainly includes a vibration platform with six degrees of freedom, a front view ring display system, a cockpit system, and high-performance workstation, which has a strong sense of immersion in driving operation. In addition, the driving simulator is equipped with multiple sensors for collecting the driver's operation and road environment information, including steering wheel angle sensor, accelerator pedal sensor, brake pedal sensor, virtual millimeter wave radar sensor, and virtual LIDAR sensor.

**Figure 7.** Composition of the driving simulator.

#### *4.2. Participants and Experimental Program*

Twenty-eight experienced drivers participated in the obstacle avoidance experiment. The ages of the drivers ranged from 23 to 48 years old, with an average age of 32.2 years (standard deviation = 5.82). Their driving experience ranged from 5 to 26 years (mean = 12.6, standard deviation = 4.6). All of the participants were non-professional drivers with a valid driver's license, normal or corrected vision, and who had experienced no serious tra ffic accidents over the past three years.

A two-way six-lane straight urban road with a length of 2 km was selected as the test section to implement the obstacle avoidance experiment, as exhibited in Figure 8. The obstacle was stationary and placed in the middle lane 1 km from the vehicle starting point. Each participant was required to navigate the vehicle at three speeds of 40 km/h, 60 km/h, and 80 km/h from the starting point, and drove forward along the center line of the middle lane. The participants were required to execute the obstacle avoidance operation in a safety distance according to their driving habits when they noticed the obstacle in front of the road. They were also required to return to the original lane after the completion of the obstacle avoidance operation. The size of the obstacle was 4710 × 1820 × 1500 mm. Each participant needed to complete three tests at di fferent speeds and try to keep a constant speed during the avoidance operation.

**Figure 8.** Schematic diagram of the obstacle avoidance experiment.
