A DEVICE THAT CONTROLS THE AZIMUTH ANDELEVATION OF A TOWED OBJECT RELATIVE TO THETOWING OBJECTThis invention relates to objects, hereafter referred to as drones, that may be towed on a flexible towline and are normally supported, in common with the tractor and towline, by the fluid medium through which they are travelling.
Drones are towed through air or water for purposes such as: being a moving target to be tracked or shot at; or perhaps for calibrating measuring equipment, by providing a known radar or optical cross-section at given distances from the measurer.
Generally, drones are supported and controlled simply by towline tension acting against fluid medium drag and gravity.
The present invention measures and resolves towline azimuth and elevation relative to the drone. These data are used, in real time, to control a pair of vanes, hereafter referred to as wings, that are attached to the drone. These controlled wings afford the operator significantly more control over the position of the drone, both vertically and horizontally, relative to the towline and tractor. Consequently the controlled flight envelope of the drone is considerably enlargened by this invention.
Furthermore, the improved control that is afforded to the drone enables a peculiar construction method to be employed which reduces bearing loads. This construction method also improves access to, and simplifies construction of, the apparatus inside the drone.
There are two aspects to the controlled flight that is afforded to the operator by thisinvention.
Firstly in elevation. (Primary method of control)A universal-shackle, linking the towline to the drone, makes an angle with the longitudinal axis of the drone. This elevation angle is continuously measured by the control-unit. The control-unit is able to drive the elevation actuator which, by means of a mechanism, moves the wings, or lift devices, to increase [or decrease] the amount of lift generated by the wings. This causes the drone to climb [or descend] as the wings bear more [or less] of the weight of the drone that was hitherto supported by the towline [or the wings].
The operator can program the control-unit to control the drone to fly at any universal-shackle elevation relative to the drone, thereby controlling the altitude of the drone relative to the towline.
The control-unit accomplishes this task by means of a feed-back loop which continuously compares the actual elevation of the universal-shackle against the required elevation of the universal-shackle. If there is a discrepancy the control-unit drives the elevation actuator to move the wings, or lift devices, to alter the lift to adjust the drones altitude relative to the towline, thereby correcting the discrepancy.
Secondly in azimuth. (Primary method of control)The universal-shackle, which links the towline to the drone, also makes an angle with the lateral axis of the drone. This azimuth angle is continuously measured by the control-unit. The control-unit is able to drive the azimuth actuator which, by means of a mechanism, moves the ailerons, or lift devices, which shifts the centre of pressure to port or starboard. This alters the rolling moment about the drones longitudinal axis and causes the drone to move laterally in the direction of the roll until there is equilibrium in that couple which exists between the moment of roll caused by the wings, or lift devices, and the moment of roll caused by any lateral component in the force exerted on the drone by the towline.
The operator can program the control-unit to control the drone to fly at any universal-shackle azimuth relative to the drone, thereby controlling the lateral displacement of the drone relative to the towline.
The control-unit accomplishes this task by means of a feed-back loop which continuously compares the actual azimuth of the universal-shackle against the required azimuth of the universal-shackle. If there is a discrepancy the control-unit drives the azimuth actuator to move the ailerons, or lift devices, which alters the rolling moment to adjust the drones lateral displacement relative to the towline, thereby correcting the discrepancy.
This controlled flight can be achieved by an alternative method.
Firstly in elevation. (Alternative method of control)The universal-shackle, which links the towline to the drone, makes an angle with the longitudinal axis of the drone. This elevation angle is continuously measured by the control-unit. The control-unit is able to drive the actuators which, by means of their respective mechanisms, move the wings, or lift devices, symmetrically, to increase [or decrease] the angle of attack and, therefore, the lift generated by the wings. This causes the drone to climb [or descend] as the wings bear more [or less] of the weight of the drone that was hitherto supported by the towline [or the wings].
The operator can program the control-unit to control the drone to fly at any universal-shackle elevation relative to the drone, thereby controlling the altitude of the drone relative to the towline.
The control-unit accomplishes this task by means of a feed-back loop which continuously compares the actual elevation of the universal-shackle against the required elevation of the universal-shackle. If there is a discrepancy the control-unit drives the actuators to move the wings, or lift devices, which alters the lift to adjust the drones altitude relative to the towline, thereby correcting the discrepancy.
Secondly in azimuth. (Alternative method of control)The universal-shackle, which links the towline to the drone, also makes an angle with the lateral axis of the drone. This azimuth angle is continuously measured by the control-unit. The control-unit is able to drive the actuators which, by means of their respective mechanisms, move the wings, or lift devices, asymmetrically, to shift the centre of pressure to port or starboard. This alters the rolling moment about the drones longitudinal axis and causes the drone to move laterally in the direction of the roll until there is equilibrium in that couple which exists between the moment of roll caused by the wings, or lift devices, and the moment of roll caused by any lateral component in the force exerted on the drone by the towline.
The operator can program the control-unit to control the drone to fly at any universal-shackle azimuth relative to the drone, thereby controlling the lateral displacement of the drone relative to the towline.
The control-unit accomplishes this task by means of a feed-back loop which continuously compares the actual azimuth of the universal-shackle against the required azimuth of the universal-shackle. If there is a discrepancy the control-unit drives the actuators to move the wings, or lift devices, which alters the rolling moment to adjust the drones lateral displacement relative to the towline, thereby correcting the discrepancy.
The reasons for, and a description of, the peculiar construction method will now beset out. Note, this applies to the alternative method of control.
The number of moving parts, and therefore the degree of complication of construction, can be reduced if the wings are fixed to their respective spars and these spars are acted upon respectively by mechanisms which rotate the spars about the lateral axis to alter the wings angle of attack. If these spars occupy the same axis through the drone, and do not overlap, then, if they are the same lateral length, they will meet at the mid-point.
A method of construction which enables the spars to occupy different axes through the drone would, consequently, enable both spars to be longer, by, for example, half the width of the drone; assuming that both spars are supported across the entire width of the drone.
There are two advantages, and one disadvantage, to a construction method that enables the spars to occupy different axes:Advantage 1The couple, about the bearings that support the spar, which occurs as a result of the forces acting on the wing, will be reduced by, for example, half; therefore the loads exerted on the bearings will be reduced by a similar amount.
Advantage 2The manufacturer will enjoy improved access to apparatus that secures the spars laterally; and to that which acts upon the spars to rotate them, about their lateral axes.
DisadvantageThe movement of the pair of wings attached to the drone by this means will not be symmetrical at all times as the wings move to alter angle of attack. The effect of this asymmetry should not be noticed by the operator, as the control afforded by the whole invention shall more than compensate.
Three specific embodiments of this invention will now be described by way of example with reference to the accompanying drawings. Example 1 is an embodiment of the primary method of control. Example 2 is an embodiment of the alternative method of control, with spars occupying the same axis. Example 3 is an embodiment of the alternative method of control, with spars occupying different axes.
Figure 1. Shows parts that are common to all examples.
Fixed inside the Chassis 1, (shown with a section cut away) is theFulcrum-Bar 2. In this drawing the Fulcrum-Bar 2, has one spar-axis; in figure VI, theFulcrum-Bar 22, has two spar-axes. The Universal-Shackle 10, is free to describe arcs about a lateral axis and an axis that is perpendicular to a line that is perpendicular to that lateral axis; these two arcs are indicated by arrows. The movement about these axes is measured by sensing equipment (not shown) and these measurements are used by the Control-Unit (not shown) to ascertain the elevation and azimuth of the towline relative to the drone. The Universal-Shackle 10, may be mounted on theFulcrum-Bar 2, as shown, or it may be mounted directly onto the Chassis 1, or onto the drone itself. Furthermore, the Universal-Shackle may be mounted in such a way as to describe pairs of arcs about the following axes:- A longitudinal, or a normal, axis and an axis that is perpendicular to a line that is perpendicular to the aforementioned axis. Or: A lateral, or a longitudinal, or a normal, axis and an axis that is perpendicular to this aforementioned axis.
The drone into which this invention is incorporated is attached to the outside of the Chassis 1.
Figure II. Example 1The Elevation Actuator 4, acts upon the Wings 7A, and 7B, by means of theLever 5, acting upon the Spar 6. The Azimuth Actuator 3, acts upon the Ailerons 8A, and 8B, by means of Bowden Cables 9A, and 9B.
Figure III. Example 1Shows a cut-away drawing of an assembly which incorporates the primary method of control.
Figure IV. Example 2The Port Actuator 4P, acts upon the Port Wing 7P, by means of the PortLever 5P, acting upon the Port Spar 6P. The Starboard Actuator 4S, acts upon theStarboard Wing 7S, by a similar mechanism.
Figure V. Example 2Shows a cut-away drawing of an assembly which incorporates the alternative method of control.
Figure VI. Example 3The Spars 26P, and 26S, may both be supported across the full lateral dimension of the Fulcrum-Bar 22. The Port Actuator 4P, acts upon the Port Wing 7P, by means of the Port Lever 5P, acting upon the Port Spar 26P. The StarboardActuator 4S, acts upon the Starboard Wing 7S, by a similar mechanism.