Coil actuator
An actuator is introduced that utilizes the forces that result from placing a current carrying coil in a magnetic field to rotate a connected object about at least one axis. In some embodiments, the introduced coil actuator includes a coil of conductor coupled to an arm or other type of structural element that extends radially from an axis of rotation. The introduced coil actuator can be utilized to provide motion control in a variety of different applications such as gimbal mechanisms. In some embodiments, the introduced coil actuator can be implemented in a gimbal mechanism for adjusting an orientation of a device such as a camera relative to a connected platform such as the body of an aerial vehicle.
1. An actuator device comprising:
a first structural element including a magnet assembly; and
a second structural element rotatably coupled to the first structural element, the second structural element including a coil arranged relative to the magnet assembly such that, current applied to the coil causes the second structural element to rotate about a rotation axis relative to a first structural element,
wherein one of the first structural element or the second structural element is statically coupled to a body of an aerial vehicle.
2. The actuator device of claim 1 , wherein the coil is a voice-coil.
3. The actuator device of claim 1 , wherein the first structural element and the second structural element are coupled via a hinge joint arranged at the rotation axis.
4. The actuator device of claim 1 , wherein one of the first structural element or the second structural element is part of a mechanical linkage in a multi-axis gimbal mechanism.
5. The actuator device of claim 1 , further comprising:
a position sensor for sensing a relative angular position of the first structural element and/or the second structural element.
6. The actuator device of claim 1 , wherein the magnet assembly includes an arc-shaped magnet that extends along a path of motion of the coil.
7. The actuator device of claim 1 , wherein the first structural element includes a flux guide having a top interior surface arranged substantially above the second structural element and a bottom interior surface arranged substantially below the second structural element, and wherein the magnet assembly comprises a first magnet coupled to the top interior surface and a second magnet coupled to the bottom interior surface.
8. The actuator device of claim 1 , wherein the magnet assembly includes one or more of a plurality of discrete magnets or an electromagnet.
9. The actuator device of claim 1 , wherein the coil is part of a flexible circuit or a rigid printed circuit board assembly (PCBA) that is coupled to the second structural element.
10. The actuator device of claim 1 , wherein the coil is arranged perpendicular to the path of motion of the arm of the second structural element.
11. An aerial vehicle comprising:
a body;
a payload; and
a gimbal mechanism coupling the payload to the body, the gimbal mechanism including:
a coil actuator for rotating the payload about a first axis relative to the body,
wherein the coil actuator includes:
a first structural element including a magnet assembly; and
a second structural element rotatably coupled to the first structural element, the second structural element including a coil arranged relative to the magnet assembly such that, current applied to the coil causes the second structural element to rotate about a rotation axis relative to a first structural element,
wherein one of the first structural element or the second structural element is statically coupled to a body of an aerial vehicle.
12. The aerial vehicle of claim 11 , wherein the gimbal mechanism further includes:
a rotary motor for rotating the payload about a second axis relative to the body, wherein the second axis is a roll axis or a pitch axis, and the first axis is a yaw axis.
13. The aerial vehicle of claim 12 , wherein the rotary motor is at least one of electrically coupled to the controller via a half bridge, and wherein the coil actuator is electrically coupled to the rotary motor or a 3-phase brushless direct current electric motor.
14. The aerial vehicle of claim 11 , wherein the coil actuator includes:
a first link arm;
a second link arm rotatably coupled to the first link arm;
a magnet coupled to the first link arm; and
a coil coupled to the second link arm, the coil arranged within a magnetic field of the magnet such that, when in use, the current applied to the coil the second link arm to rotate relative to the first link arm.
15. The aerial vehicle of claim 14 , wherein the magnet is shaped as an arc that extends along a path of motion of the coil.
16. The aerial vehicle of claim 14 , wherein the coil actuator further includes a flux guide configured to direct the magnetic field of the magnet.
17. The aerial vehicle of claim 11 , wherein the payload is a camera.
18. An aerial vehicle comprising:
a body;
a camera; and
a gimbal mechanism coupling the camera to the body, the gimbal mechanism including:
a coil actuator for rotating the camera about a first axis relative to the body, the coil actuator comprising:
a first structural element including a magnet assembly; and
a second structural element rotatably coupled to the first structural element, the second structural element including a coil arranged relative to the magnet assembly such that, current applied to the coil causes the second structural element to rotate about a rotation axis relative to a first structural element,
wherein one of the first structural element or the second structural element is statically coupled to a body of an aerial vehicle; and
a controller configured adjust the orientation of the camera relative to the body by varying a current applied at any one or more of a rotary motor or the coil actuator.
19. The aerial vehicle of claim 18 , wherein the gimbal mechanism further includes:
a rotary motor for rotating the camera about a second axis relative to the body.
20. The aerial vehicle of claim 18 , wherein the first structural element and the second structural element are coupled via a hinge joint arranged at the rotation axis.