# US 10,455,158 B2 · Stabilized gimbal system with unlimited field of regard > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,455,158 B2 - Document ID: US10455158B2 - Status: Granted - Kind: B2 - Application number: 15/268,635 - Filed: 2016-09-19 - Published: 2018-09-06 - Granted: 2019-10-22 - Earliest claimed: 2015-09-17 - Assignees: IJK Controls LLC - Applicants: IJK Controls LLC - Inventors: Gunnar G. Ristroph; Jason M. Raycroft - Web page: https://patentgrep.com/patent/US10455158B2 ## CPC - G02B 27/644: {compensating for large deviations, e.g. maintaining a fixed line of sight while a vehicle on which the system is mounted changes course} - H04N 23/69: Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming - G02B 27/64: Imaging systems using optical elements for stabilisation of the lateral and angular position of the image - H04N 23/54: Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils - H04N 23/55: Optical parts specially adapted for electronic image sensors; Mounting thereof - H04N 23/58: Means for changing the camera field of view without moving the camera body, e.g. nutating or panning of optics or image sensors - H04N 23/6812: {based on additional sensors, e.g. acceleration sensors} - H04N 23/685: {performed by mechanical compensation} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract The disclosed embodiments provide a system for controlling orientation of a payload. The system includes a gimbal structure with four or more axes. The system also includes a control system that controls the gimbal structure to provide unrestricted orientation and rotational motion of the payload mounted to an axis in the four or more axes, independently of an orientation of a base of the gimbal structure. ## Claims ### Claim 1 A gimbal system, comprising: a gimbal structure with four or more axes; and a control system comprising: one or more processors; and memory storing instructions that, when executed by the one or more processors, cause the control system to: read inputs from a set of encoders on the four or more axes and a set of inertial sensors mounted to the gimbal structure; read command input comprising a desired inertial rate for the gimbal structure; compute a set of motor commands with a first feedback control loop to achieve the desired inertial rate; and update the set of motor commands with a second feedback control loop to prevent the gimbal structure from: obscuring a line-of-sight of a payload mounted to the gimbal structure; and entering a gimbal lock configuration. ### Claim 2 (depends on 1) The gimbal system of claim 1, further comprising: a rotating joint fitted to one or more axes of the gimbal system. ### Claim 3 (depends on 1) The gimbal system of claim 1, further comprising: one or more inertial sensors that provide inertial angular rate measurements for stabilization of the payload by the gimbal structure and the control system. ### Claim 4 (depends on 3) The gimbal system of claim 3, wherein the memory further stores instructions that, when executed by the one or more processors, cause the control system to: use the inertial angular rate measurements to estimate a horizon and control a roll of the payload relative to the horizon. ### Claim 5 (depends on 3) The gimbal system of claim 3, wherein the memory further stores instructions that, when executed by the one or more processors, cause the control system to: use the inertial angular rate measurements to estimate the attitude of the payload and point the payload relative to a coordinate system. ### Claim 6 (depends on 1) The gimbal system of claim 1, wherein the payload comprises a camera. ### Claim 7 (depends on 1) The gimbal system of claim 1, wherein the four or more axes comprise: a first axis; a second axis that is perpendicular to the first axis; a third axis that is perpendicular to the second axis; and a fourth axis that is perpendicular to the third axis. ### Claim 8 (depends on 7) The gimbal system of claim 7, wherein the fourth axis comprises a large-diameter hollow mechanism within which the payload is mounted, and wherein the third axis has limited rotation. ### Claim 9 (depends on 7) The gimbal system of claim 7, wherein the third axis has a large-diameter hollow mechanism, and wherein the fourth axis has limited rotation. ### Claim 10 (depends on 7) The gimbal system of claim 7, wherein the gimbal structure further comprises: one or more additional axes of rotation fitted within or outside the first, second, third, and fourth axes of the gimbal structure. ### Claim 11 (depends on 1) The gimbal system of claim 1, wherein the control system further comprising: a relative rate feedback filter that generates commands to one or more motors coupled to the four or more axes through an inverse dynamics transform. ### Claim 12 (depends on 1) The gimbal system of claim 1, wherein the memory further stores instructions that, when executed by the one or more processors, cause the control system to: stabilize the gimbal system based on inertial rates from one or more inertial measurement units coupled to the gimbal system. ### Claim 13 (depends on 1) The gimbal system of claim 1, wherein the updating the set of motor commands with the second feedback control loop comprises: centering an axis of the gimbal system to prevent the gimbal lock configuration in the gimbal system and obscuration of the line-of-sight of the payload by the gimbal system. ### Claim 14 A method for controlling a gimbal structure with four or more axes, comprising: reading inputs from a set of encoders on the four or more axes and a set of inertial sensors mounted to the gimbal structure; reading command input comprising a desired inertial rate for the gimbal structure; computing, by a processor, a set of motor commands with a first feedback control loop to achieve the desired inertial rate; and updating the set of motor commands with a second feedback control loop to prevent the gimbal structure from: obscuring a line-of-sight of a payload mounted to the gimbal structure; and entering a gimbal lock configuration. ### Claim 15 (depends on 14) The method of claim 14, further comprising: inputting an estimated attitude of the gimbal structure into the second feedback control loop prior to updating the set of motor commands with the second feedback control loop. ### Claim 16 (depends on 14) The method of claim 14, wherein the inputs comprise: a relative angular rate measurement from the set of encoders; and an inertial rate measurement from the set of inertial sensors. ### Claim 17 (depends on 16) The method of claim 16, wherein computing the set of motor commands to achieve the desired inertial rate comprises: applying an inverse dynamics transform to the relative angular rate measurement to produce a motor torque for achieving an angular acceleration of an axis in the four or more axes. ### Claim 18 A non-transitory computer-readable storage medium containing instructions embodied therein for causing a computer system to perform a method for controlling a gimbal structure with four or more axes, the method comprising: reading inputs from a set of encoders on the four or more axes and a set of inertial sensors mounted to the gimbal structure; reading command input comprising a desired inertial rate for the gimbal structure; computing, by a processor, a set of motor commands with a first feedback control loop to achieve the desired inertial rate; and updating the set of motor commands with a second feedback control loop to prevent the gimbal structure from: obscuring a line-of-sight of a payload mounted to the gimbal structure; and entering a gimbal lock configuration. ### Claim 19 (depends on 18) The non-transitory computer-readable storage medium of claim 18, the method further comprising: inputting an estimated attitude of the gimbal structure into the second feedback control loop prior to updating the set of motor commands with the second feedback control loop.