Vehicle/vessel/airplane with a rotatable antenna

Abstract

A vehicle, vessel or airplane having an antenna and a motor rotating the antenna, a rotation encoder outputting information relating to the rotation and outputting the information to two controllers of which one controls the motor. The other controller receives the rotation information and information relating to a position/direction/axis in relation to the vehicle/vessel/airplane and outputting a second signal based thereon. The output of the second controller may be used for controlling the motor to have the antenna directed toward e.g. a satellite irrespective of the motion of the vehicle/airplane/vessel.

Claims

1. A vehicle, vessel or airplane, comprising: a radiation emitting/receiving element mounted on the vehicle, vessel, or airplane so as to be rotatable around a predetermined axis in relation to the vehicle, vessel, or airplane, an electric motor configured to rotate the radiation emitting/receiving element around the predetermined axis, the electric motor is a stepper motor comprising a static part and a rotating part comprising a first shaft and being rotatable in relation to the static part, an encoder configured to output first information relating to a rotation or rotational angle of the first shaft in relation to the static part, a first controller configured to generate a first signal to control the electric motor, and a second controller configured to receive both the first information from the encoder and second information relating to a position, direction, or axis in relation to the vehicle, vessel, or airplane, determine, based on the first information and the second information, a difference between a direction in which the radiation emitting/receiving element is presently directed and a direction or axis of the vehicle, vessel, or airplane, and a direction from the vehicle, vessel, or airplane toward the position, direction, or axis, and generate, based on the determined difference and direction from the vehicle, vessel, or airplane toward the position, direction, or axis, a second signal relating to an overall angle/direction or an angular difference or correction, around the predetermined axis, to rotate the radiation emitting/receiving element to point in or toward the position, direction, or axis, wherein the first controller is configured to receive both the first information from the encoder and the second signal from the second controller, and generate the first signal based on both the first information from the encoder and the second signal from the second controller to operate the stepper motor in a torque mode to rotate the radiation emitting/receiving element around the predetermined axis to point in or toward the position, direction, or axis, wherein the stepper motor operates in the torque mode at a desired torque regardless of speed and in which a field vector in the stepper motor is controlled to be leading or lagging a rotor of the stepper motor, such that the stepper motor operating in the torque mode causes the radiation emitting/receiving element to rotate in a continuous movement at the desired torque regardless of rotational velocity of rotation of the radiation emitting/receiving element.

2. The vehicle, vessel, or airplane according to claim 1, further comprising a second shaft extending along the predetermined axis, the radiation emitting/receiving element being connected to the second shaft, the electric motor being configured to rotate the second shaft.

3. The vehicle, vessel, or airplane according to claim 2, where one of the static part and the rotating part directly connected to the second shaft.

4. The vehicle, vessel, or airplane according to claim 2, where one of the static part and the rotating part is connected to the second shaft via a gear.

5. The vehicle, vessel, or airplane according to claim 1, wherein the second controller is configured to receive third information relating to a position, direction, or axis of the vehicle, vessel, or airplane, and generate the second signal based on the first information, the second information, and the third information.

6. The vehicle, vessel, or airplane according to claim 1, wherein the first controller is configured to operate the electric motor in the torque mode wherein the electric motor operates with the desired torque independently of both rotational speed and rotational position and in which the field vector in the electric motor is controlled to be leading or lagging the rotor of the electric motor.

7. The vehicle, vessel, or airplane according to claim 1, wherein the static part or the rotating part comprises one or more phases, one of the static part and the rotating part of the electric motor comprises a first number of phases and another of the rotating part and the static part has a second number of poles, and the first number multiplied with the second number is a pole*phase product that is at least 48.

8. The vehicle, vessel, or airplane according to claim 7, wherein the encoder has a resolution of at least 10 times the pole*phase product.

9. The vehicle, vessel, or airplane according to claim 1, wherein the first controller is configured to generate the first signal based on both the first information from the encoder and the second signal from the second controller to operate the stepper motor in the torque mode to rotate the radiation emitting/receiving element around the predetermined axis to track the position, direction, or axis as the position, direction, or axis moves in relation to the radiation emitting/receiving element, such that the stepper motor operating in the torque mode causes the radiation emitting/receiving element to track the position, direction, or axis via continuous movement at the desired torque regardless of rotational velocity of rotation of the radiation emitting/receiving element.

10. A method of operating a vehicle, vessel or airplane including a radiation emitting/receiving element and an electric motor, the radiation emitting/receiving element mounted on the vehicle, vessel, or airplane so as to be rotatable around a predetermined axis in relation to the vehicle, vessel, or airplane, the electric motor configured to rotate the radiation emitting/receiving element around the predetermined axis, the electric motor is a stepper motor comprising a static part and a rotating part comprising a first shaft and being rotatable in relation to the static part, the method comprising the steps of: I. causing an encoder to output first information relating to a rotation or rotational angle of the first shaft in relation to the static part, II. causing a first controller to receive the first information from the encoder, III. causing a second controller to receive both the first information from the encoder as well as second information relating to a position, direction, or axis in relation to vehicle, vessel, or airplane, determine, based on the first information and the second information, a difference between a direction in which the radiation emitting/receiving element is presently directed and a direction or axis of the vehicle, vessel, or airplane, and a direction from the vehicle, vessel, or airplane toward the position, direction, or axis, and generate, based on the determined difference and direction from the vehicle, vessel, or airplane toward the position, direction, or axis, a second signal relating to an overall angle/direction or an angular difference or correction, around the predetermined axis, to rotate the radiation emitting/receiving element to point in or toward the position, direction, or axis, and IV. causing the first controller to generate a first signal based on both the first information from the encoder and the second signal from the second controller to receive both the first information from the encoder and the second signal from the second controller, and generate the first signal based on both the first information from the encoder and the second signal from the second controller to operate the stepper motor in a torque mode to rotate the radiation emitting/receiving element around the predetermined axis to point in or toward the position, direction, or axis, wherein the stepper motor operates in the torque mode at a desired torque regardless of speed and in which a field vector in the stepper motor is controlled to be leading or lagging a rotor of the stepper motor, such that the stepper motor operating in the torque mode causes the radiation emitting/receiving element to rotate in a continuous movement at the desired torque regardless of rotational velocity of rotation of the radiation emitting/receiving element.

11. The method according to claim 10, wherein the first controller generates the first signal based on both the first information from the encoder and the second signal from the second controller to operate the stepper motor in the torque mode to rotate the radiation emitting/receiving element around the predetermined axis to track the position, direction, or axis as the position, direction, or axis moves in relation to the radiation emitting/receiving element, such that the stepper motor operating in the torque mode causes the radiation emitting/receiving element to track the position, direction, or axis via continuous movement at the desired torque regardless of rotational velocity of rotation of the radiation emitting/receiving element.

12. The method according to claim 10, wherein the vehicle, vessel, or airplane further comprises a second shaft extending along the predetermined axis, the radiation emitting/receiving element being connected to the second shaft, and step IV. comprises the electric motor rotating the second shaft.

13. The method according to claim 12, wherein step IV, comprises the electric motor directly rotating the second shaft.

14. The method according to claim 13, wherein step IV, comprises the electric motor rotating the second shaft via a gear.

15. The method according to claim 10, wherein step III. comprises causing the second controller to receive third information relating to a position, direction, or axis of the vehicle, vessel, or airplane, and generate the second signal based on the first information, the second information, and the third information the third information.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, preferred embodiments of the invention are described with reference to the drawing, wherein:

(2) FIG. 1 illustrates a functional block diagram of a motor control system, together with an encoder, navigation block, and control board.

(3) FIG. 2 illustrates different manners of connecting an electric motor to a radiation emitting/receiving element.

DESCRIPTION OF PREFERRED EMBODIMENTS

(4) In FIG. 1, a vessel 80 is illustrated having a radiation emitting/receiving element, such as an antenna, 50 mounted on the vessel 80. In other embodiments, the vessel can be replaced by any non-stationary system such as a vehicle or an airplane. The radiation emitting/receiving element 50 is mounted on the vehicle/vessel/airplane so as to be rotatable around a predetermined axis in relation to the vehicle/vessel/airplane. Often, antennas are rotatable around two or more axes. Each axis may be treated the same or differently, and below the rotation around only a single axis is described. The skilled person will know how to increase the number of axes/dimensions.

(5) An electric motor 10 facilitates rotation of the radiation emitting/receiving element 50 around the predetermined axis. The electric motor 10 comprises a static part and a rotating part 12. Usually, the static part has a housing 13 (see FIG. 2) and the rotating part a shaft. Usually, the motor has one or more phases 16 and one or more magnets/poles 11. In the present embodiment, 6 phases 16 are illustrated fixed to the housing, where the magnets are fixed to the shaft. In an alternative, the phases may be attached to the shaft (brushed motor) and the magnets to the housing.

(6) Naturally, any number of phases In the present embodiment only 6 phases are illustrated, but any number thereof may be used. The more phases, the higher the torque is possible at a lower RPM. Usually, the desired quantification is the multiplum of the number of phases and the number of poles. Phases*poles preferably exceeds 48. The presently preferred type of motor is one typically used as a stepper motor. Such motors have a much larger number of stators/phases than the motors typically used as brushless motors, and they usually provide a better torque/weight and torque/power ratio and a lower operating RPM

(7) A rotational/positioning encoder 20 is fixed to the first shaft 12 and outputs an output relating or corresponding to a rotation of the first shaft 12. This output may relate to an angle of rotation, an angular velocity of the rotation, a direction of rotation or the like in relation to the static part. Rotational/positioning encoders may be based on a number of technologies. In one embodiment, the rotational/positioning encoder has a disc 22 having a plurality of openings or holes 24 through which radiation may pass from a light emitter to a light receiver (not shown in the drawing) positioned on opposite sides of the disc. In another embodiment, the plurality of openings can be replaced with reflective elements, where the emitter/receiver may be on the same side of the disc. Multiple openings may be positioned at different radii of the disc and may be angularly displaced so that a direction of rotation may be inferred from an order of detection of radiation of two detectors detecting openings at different angular positions. Other types of encoders may be based on inductive elements or capacitive elements. Encoders can in general determine an incremental or an absolute rotation or angle. The rotational/positioning encoder 20 provides, to the first controller 18, information relating to a rotation or rotational angle of the first shaft 12, such as over time and/or in relation to the static part. The first controller 18 uses this information to generate a signal to drive each phase 16 of the motor 16.

(8) Operating the electric motor 10 as a stepper motor comprises feeding square-wave or micro stepping signals to the phases 16 in a manner so that the first shaft 12 rotates to a next position, where the magnetic fields of the phases will keep the shaft 12 stationary until the signals fed to the phases 16 change. This, however, may give a jerky movement.

(9) Preferably, however, the motor is operated as a brushless motor where the signal from the first controller 18 fed to each individual phase 16 producing a torque with the magnetic field vector leading or lagging the rotor, producing a controllable torque not depending on the rotation angle of the motor , so that the rotation of the first shaft 12 is more smooth than when using stepper motors. In this manner, and depending on the number of poles*phases, a high torque may be provided together with a low number of revolutions per minute as well as a smooth control.

(10) The operation of the motor 10, especially when operated with the continuous signal shapes used in torque mode, preferably is performed using the angle information derived from the encoder 20. When operating a motor as a brushless motor, the angular position between the shaft/magnet in relation to the phase 16 is desired in order to feed the correct signals to the poles so that the desired torque is produced. The same type of operation may, however, be obtained using also a brushed motor.

(11) In FIG. 2 different connections between the motor 10 and the radiation emitting/receiving element 50 are illustrated.

(12) In the left illustrations, the static part is fixed to the structure/vessel 80 and the antenna 50 is rotated by the shaft 12,

(13) In the right illustrations, the opposite is the case: the static part 13 is fixed to the antenna 50 and the rotation of the shaft 12 brings about the rotation.

(14) In the lower illustrations, the motor housing 13 is directly connected to the antenna 50 and the structure 80 whereas in the upper illustrations, the rotation takes place via a gear 200. In the present embodiments, the gear 200 is provided with two wheels 202 and 204 driving a belt 206 and where the antenna 50 is rotated around a bearing 208 via which it is attached to the structure 80. In the upper illustrations, the antenna 50 is rotated around the shaft 210 which may or may not be parallel to the shaft 12. In the lower illustrations, the antenna 50 is rotated around the shaft 12.

(15) In a preferred embodiment, the motor can rotate a payload of up to 100 kg, such as up to 1000 kg at a maximum speed of 30°/s, such as up to 360°/s.

(16) In operation, the first controller 18 may control the direction of the emitting/receiving element 50 for one of a number of reasons. In one situation, the direction of the emitting/receiving element 50 may be desired scanned along a desired path. In another situation, the direction of the emitting/receiving element 50 may be desired maintained toward a desired direction or target (such as an antenna or e.g. a satellite) irrespective of the movement of the vessel. During movement of the vessel, it may rotate, roll, pitch and yaw, where the first controller 18 may adapt the signals fed to the motor to keep the direction of the emitting/receiving element as desired. This controlling may be made on the basis of a number of types of information, such as accelerometers, signal strength gauges or the like, as is known in the art.

(17) When the antenna or radiation emitting/receiving element 50 is desired directed to e.g. a predetermined object, such as another antenna, which may be provided on e.g. a satellite, the position of the vessel is desired known in relation to e.g. a fixed coordinate system (such as the GPS coordinates) as well as the direction or heading 52 of the vessel, so that the relative angle between the vessel and emitting/receiving element 50 may be adapted accordingly.

(18) This relative angle may be derived from the output of the encoder 20, as well as output of other encoders if the emitting/receiving element 50 may be rotated around additional axes. Thus, a second controller 120 may be provided which also receives the output of the encoder 20 and into which more information is fed, such as the position/heading of the vessel, the position/ID of the antenna/satellite or the like, for the second controller to be able to e.g.

(19) output information to the motor 10 or the first controller 18 information relating to a desired relative angle or direction of the emitting/receiving element 50 in relation to the vessel, or a desired angle around the predetermined axis which the emitting/receiving element should be rotated in order to point toward the antenna/satellite desired.