## 5 Discussion
When the angular velocity exceeds 1.82 rad/s, the speed of the vehicle is automatically adjusted to 2.31 m/s over 1.6 s, because the control rule automatically adjusts the driving speed so that the speeds of the inner and outer tracks change at the same time, and a steering angular velocity of 2.2 rad/s is achieved by reducing the vehicle speed. In addition, Figure 10b shows that the pressures of the hydraulic motors on both sides increase and then decrease, and do not exceed the pressure limit of 31.5 MPa. 3. The simulation conditions are: Initial vehicle speed is 1m/s, when t = 10 s, driver inputs a steering control signal of 0.5 rad/s. If the angle sensor detects \(\alpha=30^{\circ}\), and when driving along the slope contour and turning upward, according to Formula (19), the maximum steering angular speed corresponding to the vehicle speed of 1m/s is 0.2 rad/s, which does not achieve the target steering angular speed of 0.5 rad/s. To perform the desired steering command, the vehicle speed needs to be adjusted automatically. The simulation results in Figure 11a show that the steering angular speed input by the driver increases from 0 to 0.5 rad/s within the interval 10-10.5 s. Because the driver input has not yet reached 0.2 rad/s, the control strategy does not work in the interval between 10 and 10.5 s; the inner speed is decreased and the outer speed is increased, while keeping the vehicle speed constant during steering, which fits the characteristics of differential steering. In addition, when the angular velocity exceeds 0.2 rad/s, the control rule automatically adjusts the driving speed so that the speeds of the inner and outer tracks change at the same time, so that the vehicle speed is automatically adjusted to 0.38 m/s within 2 s, and the steering target of 0.5 rad/s for the whole vehicle is achieved by reducing the driving  
Figure 10: Simulation curves of operation under Condition 2: (**a**) simulation curve of vehicle speed and steering angular velocity; (**b**) simulation curve of pressure on both sides. speed. Figure 11b shows that the pressure of the hydraulic motors on both sides increases and then decreases without exceeding the pressure limit of 31.5 Mpa. 4. The simulation conditions were: At an initial speed of 3.3 m/s and t = 10 s, the driver inputs a steering angular velocity control signal as the steering intention, the value of which increases from 0 to 3.2 rad/s within 0.5 s. If the angle sensor detects \(\alpha=30^{\circ}\) for steering downhill along the contour line, according to Formula (19), the maximum steering angular speed corresponding to the vehicle speed of 3.3 m/s is 3 rad/s, which does not achieve the target steering angular speed of 3.2 rad/s. To achieve the target steering, the vehicle speed needs to be adjusted automatically. The simulation results in Figure 12a show that when the driver inputs the steering control signal, the signal has not reached 3 rad/s, and therefore the control strategy is not triggered, in the interval between 10 and 10.5 s. To keep the vehicle speed constant during steering, the inner speed is decreased and the outer speed is increased, which is in line with the characteristics of differential steering. When the input angular velocity exceeds 3 rad/s, the control rule automatically adjusts the driving speed so that the inner and outer track speeds change at the same time, so that the vehicle center speed is automatically adjusted from 3.3 m/s to 3.1 m/s within 1.5 s. By reducing the vehicle speed, the steering target requirement of 3.2 rad/s is achieved, which shows that the control strategy is effective. Figure 12b shows that the pressure of the hydraulic motors on both sides increases and then decreases without exceeding the pressure limit of 31.5 Mpa. Figure 11: Simulation curves of operation under Condition 3; (**a**) simulation curve of vehicle speed and steering angular velocity; (**b**) simulation curve of pressure on both sides.