GB820189A - Control system for earth moving machine - Google Patents

Abstract

820,189. Automatic position control systems. COLLINS RADIO CO. June 18, 1957 [Nov. 27, 1956], No. 19193/57. Drawings to Specification. Class 38 (4). The cutting blade of an earth-moving machine is maintained at a predetermined height above a reference plane by computing the position of the blade and generating an electrical signal which then controls the blade in an undisclosed manner. It is shown that the height of the blade is equal to H + R sin (# + #) and that H= # sin f(#)dL, where H is the height of the machine itself above the reference plane, R is the distance from the cutting edge of the blade to its pivot point on the machine, # is the angle between the vertical axis of the machine and a plane perpendicular to the reference plane, # is the angle of elevation of the cutting blade with respect to the machine, and L is the horizontal distance travelled by the machine. To solve the equation for H, the angle # is measured by a vertical gyro (not shown) having a synchro take-off, Fig. 2 (not shown), which rotates the disc of a pin and slotted disc sine generator, Fig. 3 (not shown). Movement of the pin of the generator (sin #) adjusts the position of the ball-cage of a ball and disc integrator, the disc of which is rotated in proportion to L, the distance travelled, as measured by a " fifth wheel " or by movement of the machine drive. Rotation of the output roller of the integrator adjusts the slider of a potentiometer to produce an A.C. signal proportional to H. This signal is added in an undisclosed circuit to the signal proportional to R sin (#+#) to produce the blade position control voltage. The signal proportional to R sin (#+#) is generated, Fig. 4 (not shown), by connecting the synchro take-off of the vertical gyro (#) to a differential synchro, the rotor of which is moved in accordance with the blade angle (#), and passing the #+# signal to a synchro resolver from which the sine of the angle is obtained.