Multi-gimbaled borehole navigation system

An omnidirectional borehole navigation system comprising:

• a housing for traversing a borehole;
• at least one outer gimbal connected to said housing and at least two stacked inner gimbals that are nested in and connected to said outer gimbal, said inner gimbals each having an axis parallel to one another and perpendicular to an axis of the outer gimbal;
• at least one inertial sensor located on each inner gimbal, the at least one inertial sensor including at least one gyro or accelerometer, the gyros having input axes that span three dimensional space and the accelerometers having input axes that span three dimensional space;
• an outer gimbal drive system;
• an inner gimbal drive system including an inner gimbal drive motor, a rotary-to-linear gear connected to the inner gimbal drive motor, a rack connected to the rotary-to-linear gear and a plurality of pinions each engaging the rack, each pinion connected to an inner gimbal for maintaining the gyro input axes at substantially an orthogonal triad and the accelerometer input axes at substantially an orthogonal triad;
• one or more gyro circuits within the housing and responsive to the at least one gyro to produce the inertial angular rate about each gyro input axis;
• one or more accelerometer circuits within the housing and responsive to the at least one accelerometer to produce the non-gravitational acceleration along each accelerometer input axis;
• and
• a processor responsive to said gyro logic circuits and said accelerometer logic circuits for determining the attitude and the position of said housing in its borehole.

An omnidirectional borehole navigation system comprising:

• a housing for traversing a borehole;
• at least one outer gimbal connected to said housing and three stacked inner gimbals that are nested in and connected to said outer gimbal, said inner gimbals each having an axis parallel to one another and perpendicular to an axis of the outer gimbal;
• one MEMS gyro and one MEMS accelerometer located in each inner gimbal, the gyros having input axes substantially forming an orthogonal triad and the accelerometers having input axes substantially forming an orthogonal triad at each position of the inner gimbals;
• an outer gimbal drive system coupled to the at least one outer gimbal;
• an inner gimbal drive system including an inner gimbal drive motor, a rotary-to-linear gear connected to the inner gimbal drive motor, a rack connected to the rotary-to-linear gear and a plurality of pinions each engaging the rack, each pinion connected to an inner gimbal for maintaining the gyro input axes at substantially an orthogonal triad and the accelerometer input axes at substantially an orthogonal triad;
• one or more gyro circuits within the housing and responsive to the at least one gyro to produce the inertial angular rate about each gyro input axis;
• one or more accelerometer circuits within the housing and responsive to the at least one accelerometer to produce the non-gravitational acceleration along each accelerometer input axis;
• and
• a processor responsive to said gyro logic circuits and said accelerometer logic circuits for determining the attitude and the position of said housing in its borehole.