Study note 2 -- definition and value of high-precision map

This blog series includes 6 A column , Respectively ：《 Overview of autopilot Technology 》、《 Technical foundation of autopilot vehicle platform 》、《 Autopilot positioning technology 》、《 Self driving vehicle environment perception 》、《 Decision and control of autonomous driving vehicle 》、《 Design and application of automatic driving system 》.
This column is about 《 Autopilot positioning technology 》 Book notes .

---

---

1. Definition and value of high-precision map

• High precision map is used to describe roads and their lane lines in detail 、 Along the road 、 guardrail 、 Traffic signs 、 Dynamic information is the main content , With high precision 、 Multi dimensional data 、 High timeliness ;
• High precision map is also called high resolution map (High Definition Map,HD Map) Or altitude autopilot map (Highly Automated Driving Map,HAD Map);

1.1 Hierarchical structure of high-precision map

• High precision map is more accurate than ordinary navigation map 、 A map with a wider data dimension , High accuracy is reflected in the accuracy of the map to the centimeter level , The data dimension is broader. Now, except for road information, map data , It also includes surrounding static information related to traffic ;
• Ordinary map and high-precision map
  
• High precision map is mainly composed of static data and dynamic data , The static data includes the road layer 、 Lane level 、 Layer information such as traffic facility layer ; Dynamic data includes real-time traffic layer 、 Layer information such as traffic event layer ;
  
• The difference between high-precision map and ordinary map
  • precision ： The accuracy of ordinary navigation map generally reaches meter level , The accuracy of high-precision map reaches centimeter level ;
  • Use object ： Ordinary navigation maps are for human drivers , High precision maps are for autonomous vehicles ;
  • timeliness ： For static data , General navigation map update requirements are generally at the monthly or quarterly level , High precision maps generally require weekly or daily updates ; For dynamic data , Ordinary navigation maps are not required , High precision maps require real-time updates of lane level road conditions or traffic events ;
  • Data dimension ： Ordinary navigation maps only record road level data , Such as road grade 、 Geometry 、 slope 、 Curvature 、 Direction, etc , High precision map is based on ordinary navigation map , Added lane and lane line types 、 Width and other properties , And guardrails 、 Along the road 、 Traffic signs 、 Signal light and other details ;

1.2 The value of high-precision maps for autonomous driving

• Auxiliary environment perception
  The high-precision map can supplement the parts that cannot be detected by the sensor or the detection accuracy is not enough , Realize real-time condition monitoring and external information feedback , So as to obtain the accurate traffic conditions of the current location ;
• Auxiliary positioning
  When the car is running , Use map matching to accurately locate the specific position of the car on the lane , Improve the positioning accuracy of the car ; High precision map depends more on its accurate and abundant prior information ( Such as lane shape 、 Curvature and signboard ), By combining high-dimensional data with efficient matching algorithm , It can achieve higher precision matching and positioning
• Auxiliary path planning
  A high-precision map can determine the centerline of the lane , It can ensure that the car runs as close to the center of the lane as possible ; At the crosswalk 、 Areas such as low speed limits or speed bumps , The high-precision map enables the car to view in advance and decelerate in advance ; For obstacles near driving cars , High precision maps can help autonomous vehicle narrow the scope of path selection , In order to select the best obstacle avoidance scheme ;
• Auxiliary decision-making and control
  High precision map is an accurate restoration of physical environment road information , It can accelerate or decelerate the car 、 And provide key road information for driving decision control such as lane and turning ; High precision maps can provide over the horizon information for cars , It is complementary to other sensors , The auxiliary system controls the car .

1.3 Current situation of high-precision map industry