# Automatic Vertical Parking Reference Trajectory Based on Improved Immune Shark Smell Optimization
## 4 Experimental Verification
### Overall Design of the Automatic Vertical Parking Experiments  
The experimental vehicles were equipped with the system of the automatic vertical garage, composed of data acquisition sensors, a trajectory optimizer, a tracking controller, an emergency braking device, a monitoring upper computer, and other parts. Automatic vertical parking requires at least five stages: parking data acquisition, parking feasibility judgment, reference trajectory optimization, reference trajectory tracking control, and an emergency parking stop or a normal parking stop. First, parking data acquisition is necessary first, as it forms the basis of the following work. Then, the feasibility of parking based on the collected data is determined. If there are unexpected obstacles or other issues that make vertical parking impossible, the automatic vertical parking is stopped. If the parking feasibility is established, the automatic vertical parking trajectory is optimized. During this process, the vehicle remains in the starting area. Subsequently, the vehicle implements tracking control and stops when it is close to the expected parking position. At this stage, the sensor system and image transmission processing system need to detect whether there is sudden obstacle interference in real time. Automatic vertical parking also triggers vehicle correction commands if the vehicle tilts too much or is too far from its expected parking position. The overall design principle of the automatic vertical parking experiment is shown in Figure 4.  
The safety of AVP is paramount, and there can be no mistakes; so, monitoring the upper computer is necessary. In this way, the driver can view the real-time parking situation. Here, the automatic vertical garage experiment was equipped with a driver in the vehicle and a person to guarantee the ground safety. The driver was responsible for the safety of the parking experiment and the trajectory control correction of the vehicle. The driver did not control the operation of the vehicle. The driver's task was to send a stop command to the tracking controller if needed, and the tracking controller was responsible for the parking of the vehicle. The ground security person kept in touch with the driver and was responsible for observing the safety environment outside the vehicle. The security person was also responsible for taking aerial photos of the vehicle using the unmanned aerial vehicle (UAV). As shown in Figure 4, the experimental results and analysis of the automatic vertical parking were obtained using UAV aerial photography and the upper computer. The experimental configuration was as follows. The time limit for the sensor data collection was 3.5 s, 1.5 s for the parking feasibility judgment, 12 s for optimizing the  
Figure 4: The overall design principle of the automatic vertical parking experiment. reference trajectory, and 25 s for the tracking control of the reference trajectory. The time limit for the tracking controller to control the parking of the vehicle at the end was 2 s, with 0.4 s for emergency braking, if needed. The UAV was a DJI Mavic 2 DJI \"Yu\" series (Dajiang, Shenzhen, China). The upper computer was a MacBook Pro 2016 core i5 @ 2.9 GHz (Apple Inc., San Francisco, CA, USA), and it communicated via Bluetooth. Two MPC551 FMZP40 chips (from Shenzhen Yixincheng Technology Co., LTD, Shenzhen, China) were used for the trajectory optimizer (whose functions included the parking data acquisition, parking feasibility judgment, and reference trajectory optimization) and the tracking controller (whose functions included the reference trajectory tracking control, the emergency parking stop, and the parking stop), respectively; two DSP28335 chips (Texas Instruments, Dallas, TX, USA) were used for the auxiliary control unit (ACU, whose functions included the air conditioner, an overload protecting device, communication, etc.) and the actuator power unit (APU, whose functions included braking, the automobile steering gear, the braking/dynamical system, the gear control system, etc. ), respectively.