# A Novel Maneuver-Based Driving Envelope Generation Approach for Driving Safety Assessment
## 5 Experiments
The path representing the boundary path of the obstacle evasive maneuver is generated from the minimum safe distance to the obstacle, as shown in Figure 13. The algorithm complexity for calculating the safe distance and generating the evasive path with the minimum safe distance to the obstacle is \(O(n)\). Finally, the algorithm complexity of the driving envelope generation method is \(O(nlog_{2}n)\). (4). The Real Vehicle Experiment  
A modified Red Flag EHS3 based experimental platform was used to test the proposed driving envelope method. In the experimental driving scenario, a dummy was placed in the middle of the lane. A human drove the vehicle at about 20 km/h towards the dummy, as shown in Figure 22a. The driving envelope is used to determine the time for intervention and motion planning. The code is implemented in C++ using Intel I7-3520 CPU running at 3.3 GHz. The average total time used for calculating the safe distance and generating the driving envelope for both left side and right side evasive maneuver is about 1 ms. The generated driving envelope is shown in Figure 22b,c. As shown in Figure 22b,c, the interval between the marks on the longitudinal axis is 10 m; the gray parts represent obstacles detected by Lidar; the black part is the non-obstacle area; the dark blue line denotes the reference path. The driving envelope is generated in the reference frame based on the reference path. The yellow lines denote the boundary paths to arrive at the outermost safe target lateral position, the red lines denote the boundary paths to arrive at the innermost safe target lateral position. The green line indicates the predicted trajectory for the next 3 s using the constant angular velocity and constant acceleration motion model without considering uncertainty. Given the input and the state of the host vehicle, the feasibility of candidate evasive behavior can be identified quickly. At time \(t_{1}\) shown in Figure 22b, the host vehicle can  
Figure 23: The generated trajectories and the selected suboptimal trajectories for each driving maneuver. (**a**) The generated trajectories at time \(t_{1}\). (**b**) The generated trajectories at time \(t_{2}\). Figure 19.0 The driving envelope in real vehicle experiment. (**a**) The experimental scenario of collision avoidance with a dummy. (**b**) The obstacle map and the driving envelope at time \(t_{1}\). (**c**) The obstacle map and the driving envelope at time \(t_{2}\). [41]  
avoid collision from both the left side and the right side, and the driving envelopes for evasive maneuver from the both sides exist. At time \(t_{2}\), only the driving envelope for the left side evasive maneuver exists, as shown in Figure 22c. The distance for right side evasive maneuver is not enough, it is not safe to drive from the right side of the dummy after \(t_{2}\). When the probability of violating the driving envelope at the future time 1.5 s reaches 60 %, the semi-autonomous driving system intervenes. The generated trajectories and the suboptimal trajectories for the left-side and the right-side evasive maneuvers are shown in Figure 19.1 The yellow lines represent the generated trajectories, the red lines represent the selected trajectories for left-side and right-side evasive maneuvers. More detailed information on trajectory generation and evaluation methods are introduced in [41].