The guidance of the AGV refers to the actual control command value of the AGV calculated according to the position information provided by the AGV path according to the position information obtained by the AGV navigation, that is, the set speed and the steering angle of the AGV are given. This is the key to AGV control technology. In simple terms, AGV's guidance control is AGV trajectory tracking. This kind of wired guidance (electromagnetic, magnetic tape, etc.) does not have too many problems, but it is not an easy task for wireless guidance (laser, inertia, etc.).
The path planning of the AGV is to design the path trajectory of the AGV operation according to the actual environment of the AGV operation. The AGV single machine automatically travels according to the path (segment) attribute in the segment table issued by the ground control system. The AGV's guidance control algorithm is to solve the problem that the reference point of the AGV after the segment table is sent along the established trajectory. Generally, the guidance of the straight line segment and the quadratic curve is needed. For AGVs with different drive modes, the corresponding guidance control algorithms are different because of their different kinematic models. Here is a brief discussion of the guiding algorithm of the SD (Steer Driving) AGV:
Our control target is the reference point of the AGV, which aims to make the AGV walk well along the established trajectory. For the SD type AGV, only the angle and speed of the front wheel of the AGV can be controlled. According to the motion model, the running track of the reference point is only related to the steering angle of the front wheel. Therefore, to control the tracking of the reference point trajectory, In fact, it is the control of the steering angle of the front wheel.
In the specific design process, a "tracking guidance method" is used, that is, the reference point always tracks the virtual point on the path track during the operation of the AGV. This virtual point is like the rabbit used in the dog racing. The AGV can never catch up, but it is always in front of the AGV; the direction of the AGV is always pointing to the virtual point. With such periodic adjustment, the AGV can walk along the path with a small error.
