Gimbal having parallel stability mechanism

Abstract

A gimbal mechanism includes a first actuator configured to provide rotation about a central actuator axis at a first actuator speed, a second actuator co-axial with the first actuator and configured to provide rotation about the central actuator axis at a second actuator speed, and a differential member including a differential gear operatively coupled to the first actuator and the second actuator and a shaft extending between the first actuator and the second actuator. The shaft has an input end coupled to the differential gear and an output end coupled to the payload. The differential member is configured to rotate freely about a differential member axis extending along a length of the shaft. The first actuator and the second actuator are configured to cause the payload to rotate about the central actuator axis, the differential member axis, or both, based on the first actuator speed and the second actuator speed.

What is claimed is: 
     
         1 . A gimbal mechanism for providing movement of a payload about at least two degrees of freedom, the gimbal mechanism comprising:
 a first actuator configured to provide rotation about a central actuator axis at a first actuator speed;   a second actuator co-axial with the first actuator and configured to provide rotation about the central actuator axis at a second actuator speed; and   a differential member comprising:
 a differential gear operatively coupled to the first actuator and the second actuator; and 
 a shaft extending between the first actuator and the second actuator, the shaft having an input end coupled to the differential gear and an output end coupled to the payload; 
   wherein:
 the differential member is configured to rotate freely about a differential member axis, the differential member axis extending along a length of the shaft; and 
 the first actuator and the second actuator are configured to cause the payload to rotate about the central actuator axis, the differential member axis, or both, based on the first actuator speed and the second actuator speed. 
   
     
     
         2 . The gimbal mechanism of  claim 1 , wherein the shaft traverses the central actuator axis. 
     
     
         3 . The gimbal mechanism of  claim 1 , wherein the gimbal mechanism is configured to provide a full rotation of the payload about the central actuator axis. 
     
     
         4 . The gimbal mechanism of  claim 1 , wherein the gimbal mechanism is configured to provide a full rotation of the payload about the differential member axis. 
     
     
         5 . The gimbal mechanism of  claim 1 , wherein an angular speed of rotation of the differential member about the differential member axis is linearly related to a difference between the first actuator speed and the second actuator speed. 
     
     
         6 . The gimbal mechanism of  claim 1 , wherein the central actuator axis and the differential member axis are positioned at a non-zero angle relative to one another. 
     
     
         7 . The gimbal mechanism of  claim 6 , wherein the non-zero angle is  90  degrees. 
     
     
         8 . The gimbal mechanism of  claim 1 , wherein:
 the first actuator and the second actuator are configured to be actuated independently; or   the first actuator and the second actuator are fixed in position and orientation relative to one another.   
     
     
         9 . The gimbal mechanism of  claim 1 , further comprising:
 a central frame configured to support the first actuator, the second actuator, and the differential member.   
     
     
         10 . The gimbal mechanism of  claim 9 , wherein a longitudinal axis of the central frame is co-axial with the central actuator axis. 
     
     
         11 . The gimbal mechanism of  claim 9 , wherein the central frame comprises a central joint member comprising:
 an actuator joint component configured to provide free rotation about the central actuator axis; and   a differential joint component configured to provide free rotation about the differential member axis.   
     
     
         12 . The gimbal mechanism of  claim 11 , wherein the actuator joint component and the differential joint component are orthogonal to one another. 
     
     
         13 . The gimbal mechanism of  claim 1 , wherein each of the first actuator and the second actuator comprises a rotor fixedly coupled to an engagement mechanism configured to engage the differential gear. 
     
     
         14 . The gimbal mechanism of  claim 13 , wherein the engagement mechanism comprises an actuator gear or a friction wheel. 
     
     
         15 . The gimbal mechanism of  claim 13 , wherein the engagement mechanism is tapered. 
     
     
         16 . The gimbal mechanism of  claim 1 , wherein the first actuator and the second actuator are configured to cause the payload to rotate about only one of the central actuator axis and the differential member axis if the first actuator speed and the second actuator speed are identical. 
     
     
         17 . The gimbal mechanism of  claim 1 , wherein the first actuator and the second actuator are configured to cause the payload to rotate about both the central actuator axis and the differential member axis if the first actuator speed and the second actuator speed are different. 
     
     
         18 . The gimbal mechanism of  claim 1 , further comprising:
 a third actuator configured to provide rotation about a third-actuator axis different from the central actuator axis and the differential member axis.   
     
     
         19 . The gimbal mechanism of  claim 18 , wherein the third actuator is coupled to the output end of the shaft. 
     
     
         20 . The gimbal mechanism of  claim 18 , wherein the third-actuator axis is orthogonal to both the central actuator axis and the differential member axis.