APA automatic parking system

1. Semi-automatic parking

Automatic parking also known as automatic parking into place, it is a very convenient arrangement for the novice, for veterans also save a lot more effort. So what is it automatic parking of principle? Able to stop thinking about how to how to stop, like where to stop where it stopped? Here we will go for the Road said.

What is the use?

The system can automatically help the driver parked the car pulled out of parking spaces into even without playing their own direction.

What are the advantages?

Automatic parking for the novice is a very convenient arrangement for veteran is save a lot of effort. In addition, the system can avoid inadvertently cut due to the occurrence of parking rub.

Even with automatic parking assist system can not replace the driver's attention remains to be seen confirmation.
Not all gaps will automatically stop into place, the need to set aside more space to the system requirements before operating condition.
Automatic parking is not entirely without any operation by the driver, or the need to control the brake and the prompts respective engaged gear, when the driver human intervention (e.g., the direction of play), the automatic parking system will immediately stop.
After the automatic parking system is activated, the general is to find a suitable parking space, not all parking spaces are available for automatic parking. Today, many systems have not only supported parallel parking, and also enables pour garage.

Operation and condition of each brand models enable automatic parking system are not the same.

When the leaves, waste or ice cover along the road, the parking steering assistance system may be difficult to identify the curb. Further leaves and snow can also cause severe scattering of the reflected ultrasonic signal, so that the system may result in errors received weak ultrasonic echo.

If there is an obstacle warning column size smaller space on the other, the system may not recognize as valid and to the parking space, the possibility of a gap helps to increase recognition speed reduction small size articles.

In the automatic parking process the driver will have voice prompts collision may occur.

What is the technical concept of the automatic parking?

Around the periphery of the vehicle and the radar sensor measuring angular distance between itself and the surrounding objects, and then calculates the speed of rotation of the operation flow with adjustment of the steering wheel by the vehicle-mounted computer.

The system includes a data acquisition system environment, the central processor of the vehicle, and policy control systems, environmental data acquisition system comprising an image acquisition system and a vehicle from the detection system may collect data from the object from the image data and the surrounding body, and transmitted through the data line to CPU.

The central processor may be collected analysis data, auto obtained current position, target position and surrounding environmental parameters, made according to the above automatic parking strategy parameter, and converts it into an electrical signal.

After receiving an electrical signal traveling vehicle policy control system, to make the car according to the instructions of the control aspects such as the angle and direction until the parking into place.

Different automatic parking system use different methods to detect objects around the vehicle. Some four weeks in the automotive front and rear bumpers fitted with a sensor, which can act as both transmitters, can also act as a receiver. The sensor sends a signal, when the signal is outside the vehicle collides with an obstacle will be reflected. Then, the vehicle computer will use the time required for its received signal to determine the position of the obstacle. Other systems use a camera mounted on the bumper or radar to detect an obstacle. But the end result is the same: the car detects that the vehicle has been parked, the size of the parking space and the distance from the side of the road, and then the car into the parking space.

2. Automatic parking

Automatic parking assist system APA (Auto Parking Assist), the automatic parking of the vehicle by controlling the vehicle speed and the steering angle acceleration. The system through the AVM (surveying) and USS (ultrasonic radar) sensing parking environment, using the estimated IMU sensor and a wheel of the vehicle position (the position and traveling direction), and automatically or manually set according to the driver's selection of the target parking position. The system then automatically calculates the parking trajectory, and by precisely positioning the vehicle with the vehicle control system allows the vehicle along the parking locus defined fully automatic parking, until reaching the final target parking position.

introduction

When the USS before the vehicle reaches the target point detected obstacle, APA AVM and process signals from the USS, and is expected to collide, APA applying an appropriate vehicle deceleration during automatic parking.

APA automated mooring technology out of the system main functions are as follows:

Features	Explanation
Recognition of parking spaces	Parking tag includes no boundary car, parking curbs and the like has determined marked parking spaces
Automatic docking	Comprising a docking parallel, vertical docking, the docking ramps out of Formula
An automatic berth	Poise comprising a parallel, vertical poise out an oblique columnar poise
Anti-collision	Collision detection, warning, brake
HMI	Including the driver control and sound, UI instructions / tips

Parking the vehicle speed defined in claim:

Definition of speed	Search speed	Greater than the vehicle speed> 30km / h, for valid alert APA
		Speed ≤15km / h, and the search image parking space
		15km / h <speed ≤30km / h search spaces spaces
	Vehicle parking	Automatic vehicle parking control, the maximum speed of parking ≤7km / h
		Speed> 7km / h, exit APA

Technology using APA limited parking spaces product support type, the following is an overview of the specific parking supported by the minimum level schematic vertical length and the minimum width defined parking. Further, a road way along the radius of convex (or concave radius) to define inclined parking using angle, which is defined as the angle between the reference line parking parking.

name		schematic diagram
A parallel parking space	1
	2
	3
	4
	5
	6
Vertical parking	1
	2
Tilt parking	1
	3
Parking ramp	1
	2

Hardware design principles

APA parking functionality to complete, in addition to the ECU APA camera and look around sensing ultrasonic radar environment, but also closely with the vehicle body longitudinal and lateral control system, the vehicle body are related to the CAN network topology APA:

Body CAN topology

Complete automatic parking function, the vehicle stalls, EPS, ESP / ibooster, acceleration, EPB, APA control switch and indicator light or the like sensor support:

1. Looking around the parking control system 360 through information fusion parking space radar and ultrasonic.

2. APA ECU parking trajectory planning algorithm.

3. Get IMU and wheel speed pulse signal, the estimated vehicle track.

4. Get EPS steering angle, vehicle speed, gear position signal and the like, for positioning and speed control fusion.

The trajectory planning result, the gear position of the vehicle speed, steering angle of the steering control, the vehicle completed the docking poise.

APA automatic parking assist system 12 uses an ultrasonic radar, a camera and look around 4 constitute a controller, fully automatic parking function.

Software functional design

Technology APA automatic parking assist system that helps the driver safe parking.

Open parking function can be activated by a physical key (parking assist button), can also be activated by an automatic parking control button display, for example, in the control display opening (IHUs) interface driver assistance, the parking assist function interface points the toolbar, the parking operation area, the search spaces prompt area, the panoramic image display region, as shown below:

Parking search: search for the right parking system default AVM The vehicle body detecting sensor and LRU parking search system, search For parking spaces left, left turn signal can be played, and the parking spaces identified by way of AVM LRU fusion.

AVM parking Search	LRU parking Search			Fusion results
Search for parking spaces	No search spaces			AVM parking
	Search for parking spaces	Identifying within the range of AVM	Parking overlap with AVM	AVM parking
			Does not overlap the spaces AVM	LRU parking
		AVM is not identified within range		AVM parking
No search spaces				LRU parking

自动泊入：当识别到车位后，系统会提示停车，接着会请求用户点击自动泊入开关，点击自动泊入开关后，系统会提示驾驶员松开刹车开始泊车并长按APA硬按键，然后系统自动规划路径，并控制车辆完成泊车。

且看平行泊入，平行泊车位搜索完成后，APA将建立电子地图。

平行泊车电子地图

APA基于电子地图进行路径规划，路径规划问题可描述为寻求一条满足多个约束的路径曲线。

平行泊车轨迹规划

基于规划的轨迹，APA进行泊车实时控制，主要包括泊车环境实时监测、车辆位置估计、车身实时横纵向控制。

平行泊车过程中

如果实际的最终位置满足在x与y方向参数指标，则认为自动泊车正确完成（若与参考路沿对齐，则前后车轮与参考路沿的距离为25±10cm）

平行泊车完成

自动泊出

APA支持从泊车位自动泊出，驾驶员需要在自动泊出开始之前，使用转向灯指示泊出方向。其中Df和Dr是车辆到最近的前部和后部物体的距离。

平行泊出的初始条件

若与前侧参考车辆（障碍）距离符合安全距离要求，则按方式①直接前进驶出，若小于1步驶出的安全距离，则按方式②，第1步自动驶出动作默认为倒退。

平行泊出的结束条件

基于SRU的测量，车辆来回移动，直至自动驶出结束。自动驶出完成的评价标准为：当前车辆方向盘角度保持不变即可驶出泊车位并且在当前雷达探测范围内保持该线路行驶无障碍冲突。如果该过程在行驶方向角度变化达到以前没有正确结束，则APA会确定前方有障碍物，并通知停止自动泊出

泊车路径重新规划

在泊车入位过程中，车辆行驶的轨迹上可能会出现动态障碍物或静态障碍物，若行驶路径上存在静态障碍物，则需要重新对泊车路径进行规划。

如下图示例所示，车辆开始泊车后，泊车系统规划步数为两步泊入，且此时因各种原因（超声波探测距离、AVM未识别）未能识别到前方障碍物。当车辆在第一步泊入操作时US检测到前方静态障碍物，此时泊车系统根据车辆当前位置、障碍物信息、车位信息等条件，重新规划泊车路线（可能造成泊车步数增加），完成车辆的泊入。

如下图示例所示，对于内部有停车带的车位，在泊入过程中，车辆撞上减速带后（SVM未识别情况下），泊车控制系统根据发动机扭矩、轮速脉冲等信号，内部判断是否遇到减速带，并会重新规划泊车路径（可能造成泊车步数增加），在避免车辆越过减速带的前提下完成泊车。

定位与控制

泊车过程中的车辆运动姿态估计，属于短行程高精度的定位问题。采用车轮脉冲信号进行航迹推算来定位。通过单位时间内左右轮运动行程来计算车身方位角增量和后轴中心位置的增量，分别对车身方位角和位置的增量进行累加，可得出车辆的相对起始状态的位姿。

航迹推算算法适用于短行程车辆位姿定位，但该方法存在一些误差。所以需要结合其他方法共同来定位。本方案采用了结合IMU及车辆动力学模型，通过位置估计算法计算短时内高精度位姿变化，通过定位融合算法计算出最终的车辆位姿，其方法流程如下图所示：

通过车辆传感器获取的信息进行滤波，结合车辆动力学模型将传感器信息的输入应用非线性状态估计算法进行车辆状态估计，获取基于车辆动力学模型较为准确的状态信息（也就是将传感器采集的状态信息进行补偿），构建两个闭环系统进行速度控制，一部分是加减速度控制环（ESC自带），另一部分是速度控制环。

APA automatic parking system

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