# Research on the Obstacle-Avoidance Steering Control Strategy of Tracked Inspection Robots
## 5 Obstacle-Avoidance Steering Control Strategy and Simulation Analysis
### Test and Analysis of Robot Obstacle-Avoidance Steering  
In this experiment, the obstacles were set manually. The obstacle-avoidance steering process of the robot is shown in Figure 10a. It can be observed from the figure that the tracked robot completed the obstacle-avoidance steering motion according to the three schemes.  
The steering trajectory of the robot is shown in Figure 10b, where \"theoretical curve\" are the theoretical curves, which considers the influence of skid and slip on its steering performance, and \"actual curve\" are the actual curves, which do not consider the influence of sliding on steering performance. Curves 1, 2 and 3 are the obstacle-avoidance steering experiments completed by three schemes, respectively. It can be seen from Figure 9b that in the trajectory of the robot, in the initial stage, there is no error when the robot drives along a straight line in the three steering modes, but after steering, the X-coordinates of the end points are 1623 mm, 1606 mm and 1595 mm respectively, while the predetermined value is 1650 mm; however, the difference has little influence on overall steering. In particular, when the robot turns in the third scheme, the theoretical steering radius of the robot is  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Scheme 1** & **Scheme 2** & **Scheme 3** \\ \hline Steering control & Once turning in situ center & Twice turning in situ center & Large-radius steering \\ \hline Time & 10.2 s & 9.4 s & 7.5 s \\ \hline Skid rate in steering process & 0.39 and 0.35 & 0.39 and 0.35 & 0.27 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Related data comparison table of the tracked robot.  
Figure 9: Skid and slip rate. (**a**) scheme 1; (**b**) scheme 2; (**c**) scheme 3.  
R = 395 mm according to the speed difference between the track wheels on both sides of the robot, and the actual steering radius of the robot is R = 634 mm under the influence of track skid and slip, with a difference of 239 mm and a large deviation. Therefore, the track structure and road conditions of the robot should be considered for the accurate control of the autonomous obstacle-avoidance steering of the robot.  
Figure 10: Robot obstacle-avoidance steering performance test. (**a**) Robot obstacle-avoidance steering test process. (**b**) Robot obstacle-avoidance steering trajectory. (**c**) Tracked wheel motor torque in scheme 3.  
It can be seen from Figure 10c that the steering process of the robot is from 4 to 7.8 s, and the traction force of the right track wheel of the robot is significantly larger than that of the left track wheel, with a maximum traction force of 25 KN\(\cdot\)m, whereas the traction forces of the two track wheels were roughly the same at other times.  
From the above analysis, it can be seen that the robot can complete the obstacle-avoidance steering motion in three ways, which indicates that the steering control strategy is correct, and that the control strategy can provide the corresponding theoretical basis for autonomous obstacle-avoidance navigation control of the robot. The robot adopts large-radius obstacle-avoidance steering motion control, which has a smooth trajectory, fast steering speed, and the highest efficiency. However, the skid and slip of the track have a great influence on this control method; therefore, the robot driving speed, road characteristics, and other relevant information is needed, which leads to the increasing difficulty of robot control that is not easy to master.