Analysis of AGV Wheel System Layout —— The Impact of Drive Wheel Track Width

When an AGV (Automated Guided Vehicle) has two or more drive wheels, the track width of these wheels can significantly influence the vehicle’s performance in various aspects. Let’s briefly discuss some key points.

1.Effect on Friction: An appropriate track width can ensure sufficient contact area between the tires and the ground, thereby increasing friction and improving traction.

2.Effect on Pressure Distribution: A larger track width can help distribute pressure between the tires, reducing concentrated pressure on the ground. This is beneficial for driving on soft surfaces, as it minimizes tire sinking and soil compaction, thereby maintaining traction. On the other hand, a narrow track width might concentrate the tire’s projection on the ground, potentially increasing local friction but also leading to faster tire wear and ground damage.

3.Effect on Vehicle Stability: The track width also affects the vehicle’s tilt angle, correction stability, and response speed under the same control accuracy.

4.Effect on Traction: The drive wheel track width determines the projection points of the AGV on the ground. The greater the distance, the larger the power arm While the impact of the power arm is minimal during straight-line motion, it becomes a significant factor during sharp turns, particularly in-place rotations or lateral movements.

The first two points are relatively intuitive. Let’s focus on analyzing the data models related to the third and fourth points.

As shown in the diagram below, point O represents the vehicle’s center, AB and CD represent different hypothetical track widths of the same vehicle. The far right shows the projection of the four drive wheels (ABCD) on the ground.

When the vehicle moves in a straight line, the drive wheels have a minimum displacement distance. Assume the minimum displacement distance of the AGV’s drive wheels is 5mm. Under different track widths, the deviation angle between points OA and OC during the same displacement shows that a larger track width results in a smaller deviation angle. For example, the green angle Oa is smaller than the red angle OC in the diagram. This indicates that with a larger track width, the vehicle’s tilt angle relative to the straight-line motion is smaller, leading to reduced lateral oscillations during straight-line travel. Conversely, under the same stable response speed of the drive wheels, a vehicle with a larger track width takes longer to reach the same tilt angle than one with a smaller track width. This introduces a trade-off between stability and turning response, with stability often being the design priority.

When the AGV needs to rotate in place or move laterally, the power arm OA is larger than OC, indicating that with the same load, a design with a smaller track width requires greater torque. Under the same drive wheel configuration, this means that during in-place rotation or lateral movement, the motor current is lower for a larger track width compared to a smaller one, suggesting better stability with a larger track width.

Conclusion:

The optimal drive wheel track width should be determined based on specific working conditions, ground type, tire performance, and other factors. This ensures adequate traction while minimizing ground damage and tire wear. Typically, each case should be analyzed individually. In practice, we should accumulate field data and experiences, combining theory with practice. If theory is the left foot, then practice is the right foot, enabling us to take steady steps forward.