| 摘要 |
A virbometer 16 has a mass 50 suspended for vertical movement by a light spring 82 so that the mass tends to stay at a constant height reardless of angulations in the ground over which the vehicle carrying the system is travelling. The vibrometer provides one height signal by way of a potentiometer 46 and a second potentiometer 40 provides a second signal representing of the drivers seat 12. An error signal formed by a comparator 44 controls a hydraulic double acting actuator 18 so as to make the seat 12 follow the mass 50 and accordingly tend to maintain a constant height in absolute terms. In order to prevent the system becoming unstable when the ground is very rough, the mass opens limit switches 20, 22 at upper and lower limit positions and, when either switch is open, a relay 98 drops out and a solenoid valve 24 disables the actuator by connecting the two inlets 62, 64 of the actuator cylinder 60 together via a slow resistor. The relay is also deenergized when the ignition switch 26 is off. The potentiometers 46, 40 are connected between two circuit arms 36, 38 and a variable resistor 54 in the energising circuit provides gain control, ie sensitivity control. Ganged resistors 110, 112 in the two arms provide stiffness control and a resistor 116 solely in the arm 38 adjusts the main seat height. The relay 98 is of a latching relay which is reenergized by a reset switch 28. Operations of this switch sets the gain control resistor 54 to minimum gain. In a preferred construction of the vibrometer, the mass is suspended from the end of a lever arm projecting from one end of a torsion rod having the other end fixed. |
