# A Review of Recent Advances in Roll Stability Control in On-Road and Off-Road Vehicles
## 5 Roll Stability Control in Off-Road Vehicles
### Typical Roll Stability Experiments for Off-Road Vehicles  
Experimental testing of agricultural machinery, such as tractors, is a critical step in validating the effectiveness of active anti-rollover methods and control strategies [139; 140; 141; 142; 143]. Through experimental testing, the performance of different control strategies and anti-rollover technologies under various operating conditions can be accurately assessed, providing theoretical support and technical guidance for practical applications. Scale model testing, as an effective experimental method, is widely used in agricultural machinery research. Its advantages lie in the ability to simulate the behavior of real machinery by reducing the scale of the model, significantly lowering experimental costs and improving repeatability. As shown in Figure 9a, [PERSON] et al. [132] validated the SGCMG system's rollover protection through a 1:5.5 scale model experiment. The SGCMG system, using sliding mode control, achieved a 0.62 s response time, outperforming PID control. It kept the tilt angle within 40\({}^{\circ}\) and demonstrated good adaptability across speeds (0.15-0.38 m/s). As shown in Figure 9b, [PERSON] et al. [121] verified the effectiveness of sliding mode active steering control (SMC-AS) in improving tractor stability. SMC-AS reduced the side tilt by 61.3%, shortened the rollover stability time by 46.07%, and extended the safe driving range from 20\({}^{\circ}\) to 25\({}^{\circ}\), providing an improvement of 51% in emergency response time.  
Compared with the scale model testing, full-scale vehicle testing can more accurately reflect the lateral dynamics of agricultural machinery, further validating the effectiveness of rollover control measures. As shown in Figure 9c, [PERSON] et al. [51] developed an active rollover prevention control platform for a 15-horsepower small tractor, integrating central control, steering, and navigation units. Full-scale testing on slopes (8-20\({}^{\circ}\)) and various off-road surfaces demonstrated that the active steering system could steer the front wheels along the slope, effectively preventing rollover when the risk parameter exceeded the threshold. The system's effectiveness was validated in complex terrains, with remote start/stop and safety measures ensuring experimental safety. As shown in Figure 9d, [PERSON] et al. [128] tested the tractor's lateral stability and attitude adjustment through bench testing. Results showed that active attitude adjustment via the rear axle mechanism increased the tractor's instability angle from 30.91\({}^{\circ}\) to 40.74\({}^{\circ}\), improving lateral stability by 34.26%. The experimental error between the model and results was 8.12-10.14%, mainly due to unmodeled tire deformation. For tracked work machines, as shown in Figure 9e, [PERSON] et al. [13] verified automatic leveling performance through static and dynamic tests. On a 20\({}^{\circ}\) side slope, leveling took 3.3-3.4 s, with an angle of 20.8-21.2\({}^{\circ}\), and at 3 km/h, leveling reduced the tilt angle from 19.2\({}^{\circ}\) to 16.4\({}^{\circ}\), stabilizing within \(\pm\)1.5\({}^{\circ}\) after 18.2 s. The experimental results confirmed that the system could effectively maintain the stability of the machine's tilt angle, meeting performance requirements.  
Figure 9: Typical roll stability experiments for off-road vehicles: (**a**) 1:5.5 scale model test with control moment gyroscope [132]; (**b**) scale model experiment of sliding mode active steering control [121]; (**c**) integrated tractor active anti-rollover field test with centralized control, steering, and navigation units [51]; (**d**) lateral stability and attitude adjustment testing of tractor [128]; (**e**) automatic leveling performance testing for working machinery [13].