基于平滑逆死区补偿的地下铲运机线控转向控制方法

Steer-by-wire control method for underground load-haul-dump vehicles based on smooth inverse dead-zone compensation

  • 摘要: 地下铲运机电液线控转向系统存在输入死区,导致控制信号较小时铰接角响应迟滞及跟踪精度下降,但现有针对死区补偿的铲运机线控转向控制研究较少。针对上述问题,提出了一种基于平滑逆死区补偿的地下铲运机线控转向控制方法。通过单圈绝对式编码器测得实际铰接角,并与目标铰接角相减得到铰接角跟踪误差,增量式PID控制器根据铰接角跟踪误差计算PID控制信号,再由平滑逆死区补偿函数根据该信号的方向和大小叠加补偿量,生成电液比例换向阀控制信号,驱动转向油缸差动伸缩,使前后车体绕铰接销相对偏转完成转向。实车试验结果表明:采用平滑逆死区补偿后,转向响应时间缩短了23.3%,控制信号变化总量下降了约38%,表明平滑逆死区补偿在改善响应迟滞的同时有效提升了控制平顺性;阶跃轨迹跟踪时在稳定阶段的铰接角跟踪误差不超过0.5°,正弦轨迹跟踪时最大瞬时误差为4.9°,表明所提方法在不同动态特性跟踪目标下具有较高的跟踪精度;阶跃轨迹跟踪精度基本不受负载影响,正弦轨迹跟踪误差峰值随负载增大而增大,但重载工况下正弦轨迹跟踪仍能保持连续稳定。

     

    Abstract: The electrohydraulic steer-by-wire systems of underground load-haul-dump vehicles exhibit an input dead zone, causing delayed articulation-angle response and reduced tracking accuracy at low control-signal magnitudes. However, few studies have addressed dead-zone compensation in steer-by-wire control for these vehicles. To address these issues, a steer-by-wire control method for underground load-haul-dump vehicles based on smooth inverse dead-zone compensation was proposed. The actual articulation angle was measured using a single-turn absolute encoder, and the tracking error was calculated as the difference between the target and measured articulation angles. An incremental PID controller calculated a PID control signal from this error. A smooth inverse dead-zone compensation function then added a compensation term according to the direction and magnitude of this signal, generating the control signal for an electrohydraulic proportional directional valve. This valve drove differential extension and retraction of the steering cylinders, causing the front and rear vehicle bodies to rotate relative to each other about the articulation pin to achieve steering. Full-scale vehicle tests showed that smooth inverse dead-zone compensation reduced steering response time by 23.3% and total control-signal variation by approximately 38%. These results indicate that the compensation improves control smoothness while reducing response delay. The articulation-angle tracking error during the steady phase of step-trajectory tracking did not exceed 0.5°, and the maximum instantaneous error during sinusoidal-trajectory tracking was 4.9°, indicating high tracking accuracy for targets with different dynamic characteristics. Load had little effect on step-trajectory tracking accuracy. Although the peak sinusoidal-trajectory tracking error increased with load, tracking remained continuous and stable under heavy loads.

     

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