Patent GB-1052174-A (GB)
IPC: G09B9/46
Abstract: 1,052,174. Training apparatus for aircraft and ships. OTIS ELEVATOR CO. March 13, 1964 [March 18, 1963], No. 10798/64. Headings B7V and B7W. Apparatus for simulating the control of a vehicle, e.g. a helicopter, by presenting to a trainee a representation on a cathode-ray tube an indication of desired and actual conditions or positions of the helicopter comprises an oscillator 13 which supplies sine wave oscillations through transformer TR1 and phase shifter C1, RE2 to amplifiers A1 and A2, the outputs of which pass through contacts 40, 42 of commutating switch 20 to the deflection circuits of an oscilloscope 12 to provide a visual indication of a condition that a trainee has to maintain or attain. If motion has to be imparted to the image presented by the oscilloscope a synchronous motor 14 drives through gearing 15 a disc 16 having light-transmitting properties that vary with angular displacement whereby a pair of lamps L1, L2 energize through the disc photo-electric cells PC1, PC2 connected to a D.C. supply through isolating resistors R1, R2. The cells, in conjunction with resistors RE4 and RE5 form voltage dividers. the varying outputs of which are connected over lines 18, 19 to the inputs of amplifiers A1 and A2 through resistors R3, R4, thereby altering the position of the image on oscilloscope 12. Signals representative of the location of the simulated vehicle are derived in summing amplifiers SA1, SA2 (Fig. 3) and applied from leads X and Y, contacts 7, 8 and 44, 46. Switch 20 constantly switches from contacts 40, 42 to contacts 44, 46 so that indications of both actual and desired operating conditions are displayed on the oscilloscope. Fig. 2 shows apparatus for deriving signals representative of movement of a trainee's control stick 11 wherein D.C. voltage is supplied through reversing switches PS1, PS2 to potentiometers POT1, POT2, the pick-off of each of which is adjusted by control stick 11 to provide outputs corresponding to the X and Y axes. For the X axis, the output from POT1 is supplied through adjustable resistor RE6 to D.C. amplifier INT1, arranged as an integrator by feed-back capacitor C4, the integrated output being applied to a voltage divider comprising resistors R5, R6 which with inversion amplifier INV1 result in 180 degrees phase shift of the applied signal. An adjustable feedback resistor RE12 is switched at SS1 to supply positive and negative feedback to the input of amplifier INT1. The signal from amplifier INV1 is supplied through resistor RE8 to integrating amplifier INT3 and inversion amplifier INV3 whereby it is again integrated and inverted, a positive or negative feedback loop to INT1 being provided by resistor RE13. A third stage of integration may be provided by integrator INT5 and inverter INV5, and the outputs from the three circuits are taken to a manually operated Integration Selection Switch ISS whereby simulation of first, second or third order control may be selected, the appropriate order output appearing on leads X11, Y11; X22, Y22 and X33, Y33 respectively. Terminals 21-24 and, for the Y circuit, terminals 25-28 may be used to crossconnect the two branches to simulate crosscoupling along two axes, e.g. to simulate the loss of altitude that tends to accompany a turn of an aircraft. The outputs on Y11 Y22, Y33 from Fig. 2 are fed respectively to the bottom, middle and top of potentiometers POT11, POT10 and POT9, Fig. 3. The outputs from X11, X22 and X33 are fed respectively to the bottom, middle and top of potentiometers POT8, POT7 and POT6. The wipers of all the potentiometers are actuated by a reversible electric motor 29 through a reduction gear 32 and the outputs from potentiometers 9-11 and 13 are fed into the Y circuit and those from potentiometers 6-8 and 12 into the X circuit. As motor 29 progressively lowers the movable contacts the inputs to summing amplifiers SA1 and SA2 change progressively from a pure third order function to mixed third and second order functions which in turn gradually changes to the second order and then to the first order. Potentiometers 12 and 13, with rheostats RE16 and RE17, provide feedback loops to the amplifiers, to increase the amplification factor to assist the trainee. The outputs from the amplifiers pass over leads X and Y to contacts 8 and 7 respectively of switch CPS, Fig. 1, for application to the deflection circuits of oscilloscope 12. The apparatus has the characteristic of reducing its order of control, reducing the degree of movement imparted to the " target " image and increasing the gain of summing amplifiers SA1, SA2 in conformity with the degree of error. When this error exceeds a predetermined value the effect is to simplify the trainee's task and to achieve this it is desirable to change the positive and negative error signals (X-X<SP>1</SP> and Y-Y<SP>1</SP>) from' amplifiers SA3, SA4 into absolute values of negative polarity and this is done in amplifiers AV1 and AV2, the resulting X and Y axes error signals being combined in summing amplifier SA5, the output of which gives the instantaneous difference between the required and achieved performance of the trainee. Fluctuations in the. output from amplifier SA5 are smoothed by capacitors C10-C13, selected by switch EAS and the smoothed signal is amplified at A3 and fed through a switch OP and an interrupter 33 to secondary winding of transformer TR2 to produce an alternating potential that is 180 degrees out of phase with an alternating potential taken from POT3 through resistor R40, the two out-of-phase signals being combined in amplifier 31 and applied to phase winding PW2 of motor 29. The switch OP is opened to permit the setting of a stable condition of the apparatus preparatory to a trainee assuming control. In operation, and to simulate a helicopter, the various controls are adjusted until the " feel " response of the control stick 11 appears correct to an operator experienced in that particular helicopter. Switch OP (Fig. 3) is opened and switch ISS (Fig. 2) is set on position 3 so that motor 29 drives all the potentiometers POT3 to POT13 to their uppermost positions. Each input resistor RE6, RE8 &c. (Fig. 2) is adjusted to produce a customary time lag between control actuation and aircraft response and feedback switches SS1, SS2 &c. are adjusted for positive or negative feedback and resistors in the feedback loops are adjusted to simulate the stability of the craft, and the degree of response to control actuation is adjusted by resistors RE16 and RE17 in the feedback loops to amplifiers SA1 and SA2 (Fig. 3). The drive to the desired set of operating conditions is controlled by varying the output from photo-cells PC1, PC2 by adjustment of resistors RE4, RE5. Switch CPS (Fig. 1) will be set to the right-hand set of contacts if the trainee's object is to maintain a visual representation of the simulated helicopter in registration with a simulated desired position of the helicopter. For a training session switch OP is closed and a trainee attempts to maintain registration between the images on the oscilloscope. Any signals representing error are summed in amplifiers SA1 and SA2 and returned over leads X and Y to switch CPS for operation of the deflection circuits of oscilloscope 12. Simultaneously signals from photo-cells PC1, PC2 are supplied through switch CPS and switch 20 to the deflection circuits and over leads X<SP>1</SP> and Y<SP>1</SP> to the inputs of summing amplifiers SA3 and SA4, where they are combined with the integrated signals resulting from the control actuations to produce more or less constantly varying values indicative of the deviation that the trainee achieves from a desired position.