Patent GB-428533-A (GB)
Title: Improvements in and relating to automatic steering
IPC: G05D1/02
Filed: 1933-11-10
Abstract: 428,533. Automatic control of ships &c. HENDERSON, SIR J. B., 38, Blackheath Park, Blackheath, London. Nov. 10, 1933, Nos. 31377/33 and 6738/34. [Classes 113 (i) and 114] [See also Groups XIX and XX] A relay mechanism for restoring an axis fixed in a body to its original position after deviation at a rate proportional to the amount of deviation #, the angular velocity of deviation #, and the angular acceleration of deviation ##, comprises a constrained gyroscope for measuring the angular velocity and actuating a continuously variable speed gear for deriving the angular acceleration. The relay may be used for controlling the steering, pitching, and rolling of ships, submarines, or aircraft. In the form shown in Figs. 1 and 2, the rotor 1, mounted on the hollow spherical bearing 2 and driven by motor 4 through the flexible coupling 5, is constrained by the bell-crank lever 6 which is mounted on a pivot pin 7 carried by a bracket 8 and engages an extension of the rotor 1 by means of a spherical joint 9. The lower end 12 of the lever 6 has a restricted movement between two contacts 10, 11, controlling a motor 13 geared at 14, 15 to the pivot pin 7. A flat spring 16 fixed to the pin 7 engages between a fork 17 fixed to the lever 6. Closure of one of the contacts 10, 11, 12 due to precession of the gyro upon turning of the craft causes the motor 13 to rotate until the tension of the spring 16 overcomes the precessional force and breaks the contact. The number of revolutions made by the spindle 19 of the motor 13 is then proportional to ##, the velocity of displacement of the craft. The spindle 19 is geared to a shaft 25 having a screw 22 adapted to move a box c carrying rollers a, b over a friction disc 20 driven at constant speed from the motor 4 through gearing 21, 27' and shaft 18. The rollers a, b are interconnected by a differential gear so that the number of revolutions of the epicyclic member and the shaft 24 connected to it is proportional to 6, the angle of displacement. A second screw 32 on the shaft 25 traverses a second box c carrying rollers a, b resting on a friction disc 30 similar to the disc 20. These rollers a, b are interconnected by a differential gear, the epicyclic member of which is geared through pinions 35, 36 to a nut 33 rotatably mounted on a housing 38 integral with the box c. The latter is moved across the friction disc 30 until the speed of rotation of the nut 33 equals that of the screw 25, i.e. is proportional to 6. Since the speed of the nut 33 is proportional to the displacement of the box c over the disc 30, ## is proportional to this displacement, viz. the difference between the number of revolutions of the shaft 25 and nut 33. The revolutions of the shafts 24 and 25 and the difference between the revolutions of shaft 25 and nut 33 are added up in the required proportions along the shafts 41, 44, 46, 50. A hand adjustment may be given to the shaft 41 by the worm gear 40. The 6 term is then added by a differential gear 42, the epicyclic member of which is driven from shaft 24 through gearing 26, 27. The # term and the revolutions of the shaft 25 required for the ## term are then added to the revolutions of the shaft 44 by differential gear 45 and gearing 39. The revolutions of the nut 33 are then subtracted from the revolutions of the shaft 46 by differential gear 47 and gearing 37, 48 and the sum ##+ 2A## + (A<2> + B<2>)# + hand adjustment is obtained on shaft 50. If the rudder &c. is to be controlled on a displacement basis, a contact arm 51 on the shaft 50 co-operates with a twopart commutator 52 on a worm wheel 53 to actuate a motor 55 which drives the steering gear and causes the wheel 53 to follow the motion of shaft 50. Alternatively, the rudder &c. may be controlled on a velocity basis by using the revolutions of the shaft 50 to vary the transmission ratio of a continuously variable speed gear 56, the output of which drives the steering gear through a sprocket 62. In a modification the contacts 10, 11, 12 control a motor driving a screw adapted to traverse the rollers a, b over the friction disc 30. The epicyclic member driven by the rollers a, b is geared to the shaft 25 and in turn to the shaft 19 geared to the spring 16. The motor therefore runs until the number of revolutions of the shaft 25 is proportional to ##. Accordingly the number of revolutions of the traversing screw is proportional to 6. A variable speed gear similar to 20 and controlled by a screw on the shaft 25 provides a member whose revolutions are proportional to #. The revolutions of the different members are added as in Fig. 2. In this modification as in the one described below, the mechanism determining the acceleration ## is the first to be put into motion upon precession of the gyro, thereby applying that part of the control depending on # at the earliest possible moment. Fig. 4 shows an alternative device for measuring ## and ##. A gyro 80 pivoting on trunnions 81 in a frame 82 and constrained by a spring 83 has a contact arm 87 co-operating with a two-part commutator 88 attached by a stiff spring 89 to a follower 85 pivoted on trunnion 84. The follower 85 is driven through gearing 95, 96, 97 by the variable speed shaft 91 of a continuously variable speed gear 92, the disc being driven by a separate motor 93. The variation of speed of the shaft 91 is controlled through screw 98 and gearing 101 by a motor 100 actuated by contacts 87, 88. Since the arrangement causes the follower 85 to follow the contact 87 as the gyro precesses through an angle proportional to 6 the speed of the shaft 91 and therefore the angular displacement of the screw 98 or shaft of the motor 100 is proportional to ##. The angular displacement of the shaft 91 is proportional to ##. To reduce hunting, the outer casing 102 of a viscous or eddy current brake on the spindle of motor 100 is connected by an arm 103 to the top of the spring 89 carrying the contacts 88. Specification 247,633, [Class 114], is referred to.