AGV Guidance refers to calculating the actual control command value of the AGV according to the position information obtained by the AGV Navigation according to the target value provided by the path of the AGV, that is, giving the set speed and steering angle of the AGV, This is the key to AGV control technology. In simple terms, the guidance control of AGV is AGV trajectory tracking. This will not have too many problems with wired guidance (electromagnetic, magnetic tape, etc.), but it is not an easy task for wireless guidance (laser, inertial guidance, etc.).
AGV Running Path Trajectory
The path planning of AGV is to design the path trajectory of AGV operation according to the actual environment of AGV operation, and the AGV single machine automatically travels according to the path (segment) attributes in the segment table issued by the ground control system. The guidance control algorithm of the AGV is to solve how the reference point of the AGV walks along the established trajectory after the segment table is issued. Generally, it is necessary to realize the guidance control of the straight line segment and the quadratic curve. For AGVs with different driving methods, due to their different kinematic models, the corresponding guidance control algorithms are also different. Here is a brief discussion of the steering algorithm of SD (Steer Driving) AGV:
Our control target is the reference point of the AGV, and the purpose is to make the AGV walk along the established trajectory well. For SD-type AGV, only the rotation angle and speed of the front wheel of the AGV can be controlled. Through the motion model, it can be known that the running trajectory of the reference point is only related to the steering angle of the front wheel. Therefore, to realize the control of the trajectory tracking of the reference point, In fact, it is the control of the steering angle of the front wheels.
In the specific design process, a "tracking and 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 dog racing. The AGV can never catch up, but it is always not far in front of the AGV; the forward direction of the AGV always points to the virtual point. Through such periodic adjustment, the AGV can walk along the path trajectory with a small error.