# Research on the Obstacle-Avoidance Steering Control Strategy of Tracked Inspection Robots
## 5 Obstacle-Avoidance Steering Control Strategy and Simulation Analysis
### Simulation Analysis of Obstacle Avoidance Steering Motion  
Based on a theoretical analysis of the steering control strategy of the robot's angular obstacles, it was found that the robot can choose many schemes when facing an angular obstacle. The 3D models of the robot and terrain were established using Solidworks software according to the parameters. The 3D models were converted into X_T format and then imported into ADAMS simulation software. Constraints were added to test models through the simulation software, and motor drive functions were edited to make the robot walk according to the predetermined trajectory. The robot's driving road has no mutation, and friction coefficients between robot's track and road were the same. Finally, the corresponding simulation test was completed. In the process of obstacle avoidance and steering, the robot implemented the necessary acceleration and deceleration motions and maintained full speed at other times. The maximum inspection speed of the robot was set at 550 m/s. The steering velocity curve of the tracked robot and angular velocity of the track wheel are shown in Figure 8, where Angular_v_R is the angular velocity of the right track, Angular_v_L is the angular velocity of the left track; V is the actual velocity of the robot, and V' is the theoretical velocity of the robot (regardless of the skid and slip). The skid or slip rate of right track is defined as iR, and  
Figure 7: Principle analysis of robot steering. i\({}_{\text{L}}\) is the skid or slip rate of left track; the numbers 1, 2, and 3 are the steering movement of the robot in the three schemes. It can be seen that all tracked robots can complete obstacle-avoidance steering as required; however, they have their own characteristics. The robot completes the obstacle steering movement through scheme 1, which requires three rounds of steering and speed switching of the track's drive motor on both sides. This scheme is easy to control; however, the steering time is long, requiring 10.2 s, and the required space for steering is large. When the robot was in a narrow space, it was not conducive to steering. The robot can complete the angular obstacle steering movement through scheme 2, which is simple to operate and requires 9.4 s, less time than scheme 1, but it needs to switch the steering and speed of the two motors five times. In this steering scheme, the robot is prone to collision at the corner point; therefore, special attention should be paid to controlling the corner points. The robot can complete the angular obstacle steering movement through scheme 3, which only needs to switch the steering and  
Figure 8: Angular obstacle-avoidance steering simulation. (**a**) Obstacle-avoidance steering motion shown in scheme 1 (10.2 s); (**b**) Obstacle-avoidance steering motion shown in scheme 2 (9.4 s); (**c**) Obstacle-avoidance steering motion shown in scheme 3 (7.5 s). speed of the right motor once, which takes 7.5 s. This steering scheme requires a small space range and has good stationarity; however, the skid and slip rates are high in the steering process. Therefore, it is necessary to fully grasp the driving and road characteristics of the tracked robot and provide accurate motor driving parameters to realize it. The skid and slip rate of the tracked robot through three strategies are shown in Figure 9. The part above the zero-axis is the slip rate, and the part below the zero-axis is the skid rate. From the figure, it can be seen that skid and slip will be shown at different stages of the robot's steering. At the moment when the robot starts, the robot slips, which decreases with the increase of the robot's speed, as shown in point A in the three figures. The slip rate of the tracked robot is small when robot drive in a straight line, as shown in point B.