Patent GB-583839-A (GB)
Title: Improvements in control systems for power-driven objects
IPC: G05D3/12
Filed: 1941-12-01
Abstract: 583,839. Positional control systems. TUSTIN, A., WELLS, D. W., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Dec. 1, 1941, No. 15479. [Class 40 (i)] In a positional control system for a powerdriven object such as guns, rudders, fluid valves moved by electric, hydraulic or other motors, the motor is controlled by (1) means causing it to apply a torque component dependent upon the displacement between the object and a control member (2) means responsive to resistance to rotation of a shaft loaded in accordance with its velocity which is dependent wholly or in part on the velocity of the control member to cause the application of a corresponding torque component which aids the abovementioned component, and (3) means respon- .sive to the velocity of the driven object to apply a component in opposition to the abovementioned components. The arrangement shown in Fig. 1 is a modification of Fig. 1 of Specification 583,836 in which the loading of supplementary shaft 10 by coupling 27, 28 is dependent on the velocity of the control member 3 instead of the relative velocity between the member 3 and driven shaft 4. Other means are provided for introducing a component of torque. dependent on the velocity of the driven shaft, such as an auxiliary exciter winding (Fig. 2, not shown) for a control metadyne, the winding being controlled by voltage across the armature of the driving motor controlled by - the metadyne. Limit switches and resistances may be used to control the voltage applied to the auxiliary winding. Alternatively, a tachometer generator may be used to provide this component. In Fig. 1, casirig 1 contains a twopart variable resistance controller (Specification 577,312, [Group XXXVII]) over which torque is applied from shaft 3 to shaft 10 which is coupled by spring devices 31-33 (Specifications 577,489, [Group XXIV], and 583,838) to casing 5 rigid with shaft 4 so that shaft 10 is loaded in accordance with displacement between 3 and 4 and reacts on the resistance controller. The part 27 of the coupling is' fixed in space in the present case instead of being carried by casing 5. The driving system may be of the Ward-Leonard type, and shaft 10 may be loaded to introduce acceleration and friction components. The motive equipment may also be controlled by a moving coil relay particularly when it comprises a variable velocity ratio hydraulic transmission system. The invention is also applicable to other arrangements described in Specification 583,836. A further arrangement (Fig. 3, not shown) comprises a modification of Fig. 1 of Specification 583,835 in which the planet gear of a differential is driven by the control member, one sun pinion being connected to the supplementary shaft loaded to introduce various components and the other sun pinion being connected through a variable resistance controller to the driven member. In the present case, the velocity loading of the supplementary shaft comprises a coupling between the shaft and a member fixed in space and although the shaft derives movement from both the control member and the driven object, it provides, owing to the arrangement of the differential gear, a component dependent on the velocity of control member alone in addition to a relative velocity component. An additional component dependent on the velocity of the. driven object is introduced as previously described, together with components depending on acceleration and friction.