Patent GB-1240896-A (GB)
Title: An analogue-programmed device for excavator control
IPC: G06G7/64
Filed: 1968-09-16
Abstract: 1,240,896. Analogue computer for excavator control. UNICOVSKE STROJIRNY, NARODNI PODNIK. 16 Sept., 1968 [14 Sept., 1967], No. 43979/68. Heading G4G. In analogue control of a rotary excavator having a rotor carried by a jib the rotor position is represented by co-ordinates #x, #z referred to vertical and horizontal axes z, x and angle # of the projection of x referred to the line of advances of the excavator through the origin in a horizontal plane. Jib DJ (Figs. 1, 3) of length 1 is articulated at J and angled α to a plane a parallel to the plane of advancement, while it is movable along I G of length 2h angled # to plane b also parallel to the plane of advancement. A selsyn energized by voltage proportional to 1 is positioned at J and produces voltages (l sin a, l cos α) representing the projections of the jib, and a double potentiometer driven by the displacement of point J along IG produces voltages representing the projections of h (= GJ). A further voltage represents the height d of G above the plane of advancement and by summation of voltages, signals x 2  and z 2  are produced proportional to #x and #y the co-ordinates of D referred to axes z, x. In a computer (Fig. 2) signal #x is applied to servomultiplier N and to first adder S 1  feeding first amplifier A. Signal z is applied to third adder S 3  feeding second amplifier B. The amplifier outputs are gated at H 2 , H 4  to control drives F, E for x and y displacement of the rotor, with corresponding changes of inputs of pickups U, T responding to co-ordinates x, z. Selsyn analyser pickups M responsive to angle # of the excavator swing motion and selsyn analyser pick-up R responsive to the inclination 8 of the excavator feed three inputs of servomultiplier N. Pick-up R is displaced as a whole by deflection # and comprises a selsyn, whose rotor is held in constant position by an oil damped eccentric weight, while its stator is rotated by the inclination 8 # tan 8 (Fig. 5) of the excavator displacement plane to the horizontal. The outputs x 2  cos # and x 2  sin # of servo multiplier N are connected to adder S 8  over potentiometers O, P multiplying by constants k 1 , k 2  representing manually selectable gradient values. The output of S 8  is gated at H 8  to adder S 7  also receiving over gate H 9  the output x 2  tan 8 from servomultiplier N. The input of S 3  is derived from the output of S 4  together with signal z 2  from T, and the output of S 7 , while S 4  also receives the output of potentiometer P 5  (manually preset to z 0  for depth of cut) over gate H 10  and that of P 2  direct. Potentiometer Q adjustable manually to determine excavation gradient multiplies Z 1  by constant k 1  and is energized from the output of S 4  and energizes adders S 2 , S 6 ; adder S 1  being energized from the output of S 2 , which also receives input over gate 11 from potentiometer P 4  (manually set to introduce constant x 0  for thickness of cut) and from potentiometer P 1  direct, together with the output of adder S 5  over gate H 7 . Potentiometer P 1  is adjusted to x 1  over gate H 1  in response to the output of amplifier A. Adder S 5  is energized by the output of adder S 6 , over gate H 6 , and its output energizes amplifier C which adjusts potentiometer P 3  to x 1  over gate H 5  to supply feedback to adder S 5 . Amplifier C also energizes swing motion drive V of the excavator to vary angle #, in turn varying the output of selsyn pick-up M. Potentiometers P 1 , P 2 , P 3  controlled by gates H 1 , H 3 , H 5  are mechanically varied in response to the outputs of amplifiers A, B, C and develops auxiliary values x 1 , z 1 , x1 1  fed into the system. According to the settings of gates H 6  to H 11  the sums of the several voltages are derived by adders S 1  to S 8  and are transferred from adders S 1 , S 3 , S 5  to amplifiers A, B, C which according to the settings of gates H 1  to H 5  operate to reset potentiometers P 1 , P 2 , P 3  and develop auxiliary voltages x 1 , z 1 , x 1 1 or control drives E, F, V to develop new output values of x, z, e. The manually selected programme controls the sequence of operations of the excavator as to frontal and lateral slope, plane of excavation and depth of cut by automatically, sequentially and selectively operating gates H 1  to H 11 . Several programmes for different operating sequences are described in the mathematical analyses.