STUDY ON ACTIVE ANTI ROLLOVER CONTROL AND MODEL TEST OF TRACTOR MOMENTUM FLYWHEEL

The tractor working environment is complex and changeable, and the dynamic variation range of the center of gravity position of the tractor body is large. In order to avoid rollover accident, an active anti rollover control method of tractor momentum flywheel and its model test are proposed in this paper. The tractor dynamic system model and control strategy are verified by a 1:16 scale tractor model. The research results show that when the model tractor crosses the trapezoidal obstacle B, the roll angle of the whole machine is temporarily stable near 35 °, indicating that at this time, the tires on one side of the whole machine are in actual contact with the obstacle, showing a short stable state of the whole machine. When the pavement roughness reaches F-H level, without any active anti rollover control, the evaluation index EP shows a divergence trend when it is greater than 1, and the simulation calculation is terminated due to the occurrence of rollover of the whole machine. The test data and simulation results under two different driving speeds are in good agreement, which verifies the effectiveness and reliability of the tractor rollover dynamic system model and the momentum flywheel active stabilization system.

Realization of a Continuously Phase-Locked Few-Cycle Deep-UV/XUV Pump-Probe Beamline with Attosecond Precision for Ultrafast Spectroscopy

Chemical and physical processes in molecules can be controlled through the manipulation of quantum interferences between rotational, vibrational, and electronic degrees of freedom. Most of the past efforts have been focused on the control of nuclear dynamics. Even though electronic coherence and its coupling to nuclear degrees of freedom may profoundly affect the outcome of these processes, electron dynamics have received less attention. Proper investigation of electron dynamics in materials demands ultrafast sources in the visible, ultraviolet (UV), and extreme ultraviolet (XUV) spectral region. For this purpose, a few-cycle deep-UV and XUV beamlines have been constructed for studying ultrafast electron dynamics in molecules. To ensure the required high temporal resolution on the attosecond time scale, vibration isolation from environmental mechanical noise and active stabilization have been implemented to achieve attosecond timing control between pump and probe pulses with excellent stability. This is achieved with an actively phase-stabilized double-layer Mach-Zehnder interferometer system capable of continuous time-delay scans over a range of 200 fs with a root-mean-square timing jitter of only 13 as over a few seconds and ~80 as of peak-to-peak drift over several hours.