英文释义:
http://gps.about.com/od/glossary/g/Heading.htm
Definition: The compass direction toward which a traveler or vehicle is (or should be) moving. 
Examples:
"This heading will take us to the north side of the lake. Once there, we can follow a new heading to the lodge."

Definition: The compass direction from your current position to your intended destination. Bearing is used to describe the direction of a destination or object.
Also Known As: Azimuth
Examples:
"The lodge is at a bearing of 85 degrees (east-northeast)."

中文释义:
heading:是机器人方向与屏幕正上方的角度差,方向在0到360之间。
bearing：是机器人的某个部件如雷达发现的目标与方向的角度差，顺时针为正角度在-180到180之间。