Robust singularity avoidance in satellite attitude control

• US 6,039,290 A
• Filed: 03/16/1998
• Issued: 03/21/2000
• Est. Priority Date: 03/16/1998
• Status: Expired due to Fees

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Wie, Bong, Heiberg, Christopher J., Bailey, David A.
• Primary Examiner(s): Poon, Peter M.
• Assistant Examiner(s): Dinh, Tian
• Application Number:
  US09/039,959
• Time in Patent Office: 736 Days
• Field of Search: 244/165, 244/171, 244/164
• US Class Current: 244/165
• CPC Class Codes: B25J 9/1607 Calculation of inertia, jacobian matrixes and inverses
• CPC Class Codes: B64G 1/286 using control momentum gyroscopes (CMGs)
• CPC Class Codes: B64G 1/36 using sensors, e.g. sun-sensors, horizon sensors

Abstract

Control moment gyros in an array are rotated to reorient a satellite. A pseudo inverse control is employed that adds a term to a Moore-Penrose pseudo inverse to prevent a singularity.

Claims

1. A satellite attitude control comprising a plurality of control moment gyros in an array and a controller for changing a gimbal angle on each gyro, characterized in that the controller comprises signal processing means comprising:

means for receiving a desired satellite attitude signal;

means for producing an actual satellite attitude signal;

means for producing an attitude error signal from desired satellite attitude signal and the actual satellite attitude signal;

means for producing a torque command signal in response to the attitude error signal;

means for producing an angular rate signal for each gyro using a pseudo inverse control law that uses said torque command signal and a Jacobean value for the angle of the a gyro, said pseudo inverse including a term that prevents a singularity in the angular rate signal; and

means for rotating a gyro in the array in response to the angular rate signal.

2. The satellite control described in claim 1, further characterized in that:

the term prevents the pseudo inverse from being indeterminant.

3. The satellite control described in claim 1, further characterized in that:

said pseudo inverse is A^T (PAA^T +kI)^-1 P, where A is the Jacobean value of the CMG array.

5. The system described in claim 1, further characterized in that:

the term prevents the pseudo inverse from being indeterminant.

6. The system described in claim 1, further characterized in that:

said pseudo inverse is A^T (PAA^T +kI)^-1 P, where A is the Jacobean value.

4. A robotic system characterized by a plurality of actuators controlled by a signal processor according to a control law to control an element, characterized in that the signal process comprises:

means for producing an error signal representing the difference between a desired and actual position for the element;

means for producing a rate signal manifesting a desired rate of change in the position of the actuators in response to said error signal;

means for producing a signal that controls the rate of actuator movement by each actuator using a pseudo inverse control law that uses said torque command signal and a Jacobean value for the angle of the actuator, said pseudo inverse including a term that prevents a singularity in the angular rate signal.