# Simulation and Validation of a Steering Control Strategy for Tracked Robots
## 5 Simulation Analysis of Obstacle Avoidance Steering Control  
### Obstacle Avoidance Steering Control Strategy for Tracked Robot  
As shown in Figure 9, there are multiple paths for the robot to choose during the obstacle-avoiding steering movement from point A to point B, and there will be no collision with the surrounding obstacles during this process. For example, the robot realizes obstacle avoidance steering movement through center steering and differential steering, as shown in Figure 9. Center steering refers to a tracked robot's maneuver where one side of the tracks moves forward while the other side moves backward at the same speed, causing the robot to rotate around its own center. Typically, this method requires the robot to come to a halt before executing center steering and is commonly used when the robot needs to make sharp turns in extremely confined spaces. Differential steering, on the other hand, involves a tracked robot changing its direction by altering the speed difference between the two tracks while keeping both tracks in continuous motion. This allows the robot to maintain its movement without stopping and is suitable for making turns in more spacious environments.  
In the process of center steering movement, the robot can reach point B from point A through two executions of center steering, that is, the robot rotates counterclockwise at point C and clockwise at point D, and the trajectory of the robot is ACDB, as shown in strategy 1 in Figure 9. Similarly, the robot can get from point A to point B through four center turns, and the trajectory of the robot is AEFGHB, as shown in strategy 2 in Figure 9. In the differential steering motion, the robot completes the obstacle-avoiding steering movement through two differential steering movements, and the steering trajectory of the robot is AKOJLB, as shown in strategy 3 in Figure 9.  
Trajectory ACDB: The steering angle of the robot at point C can be calculated using the following formula, where clockwise rotation of the robot is negative, counterclockwise rotation is positive, and the steering angle of the robot at point D is opposite to the steering angle of the robot at point C.  
\[\angle DCo_{2}=\arctan\frac{D_{y}-C_{y}}{D_{x}-C_{x}} \tag{13}\]  
Figure 9: Obstacle avoidance steering control strategy.  
Trajectory AEFGHB: The steering angle of the robot at point E can be calculated using the following formula. Points F, G, and H can be calculated using the similarity formula.  
\[\angle{FE}{{\it{0}}_{2}}=\arctan\frac{{{\it{F}}_{\rm{y}}-{\it{E}}_{\rm{y}}}}{{{\it{ F}}_{\rm{x}}-{\it{E}}_{\rm{x}}}} \tag{14}\]  
Trajectory AKOJLB: The steering radii of the robot are \(O_{1}O\) and \(OO_{2}\), respectively. When the steering radius of the robot is equal at the two stages of the steering process, the \(O\) point is on the midpoint of \(O_{1}O_{2}\), that is, \(O_{1}O=OO_{2}=R\), then \(OM=O_{2}K/2\) and \(O_{1}M=O_{1}K/2=R/2\). The following formula can be derived from the right triangle \(O_{1}MO\) relation:  
\[O_{1}O=O_{1}M^{2}+OM^{2} \tag{15}\]  
The robot steering radius formula can be obtained by simplifying the formula as follows:  
\[R=\frac{\sqrt{3}}{3}O_{2}K \tag{16}\]