Directional drilling control devices and methods

1. A drill control system comprising:

an uphole control device; and

a downhole control device;

wherein the uphole control device is configured to:

transmit a reference trajectory to the downhole control device; and

receive information about an actual trajectory from the downhole control device; and

transmit control signals to the downhole device to control rotational speed of a drill bit based on information received from the downhole control device; and wherein the downhole control device is configured to:

receive the reference trajectory from the uphole control device;

calculate a confidence interval for the reference trajectory;

reject disturbances in the actual trajectory which are considered noise;

measure the actual trajectory;

correct deviations between the reference trajectory and the actual trajectory exceeding the confidence interval; and

transmit information about the actual trajectory to the uphole control device, wherein the uphole control device implements an uphole control loop and the downhole control device implements a downhole control loop, the uphole control loop having larger sampling intervals than the downhole control loop while monitoring the performance of the downhole control loop to facilitate drilling to a defined target.

2. The drill control system of claim 1 , wherein the downhole control device transmits drilling performance information to the uphole control device.

3. The drill control system of claim 2 , wherein the drilling performance information includes at least one selected from the group consisting of: rotational speed, rotational acceleration, orientation, inclination, azimuth, build rate, turn rate, and weight on bit.

4. The drill control system of claim 2 , wherein the reference trajectory is calculated and updated in response to the drilling performance information.

5. The drill control system of claim 1 , wherein the downhole control device transmits geological information to the uphole control device.

6. The drill control system of claim 5 , wherein the geological information includes at least one selected from the group consisting of: geological properties of formations in front of a bit, and geological properties of formations adjacent to the bit.

7. The drill control system of claim 5 , wherein the reference trajectory is calculated and updated in response to the geological information.

8. The drill control system of claim 1 , wherein the uphole control device and the downhole control device communicate with fluid pulses.

9. The drill control system of claim 1 , wherein the uphole control device and the downhole control device communicate with electrical signals.

10. The drill control system of claim 1 , wherein the uphole control device and the downhole control device communicate with radio signals.

11. The drill control system of claim 1 , wherein the downhole control device is in communication with one or more directional steering devices.

12. The drill control system of claim 1 , wherein the downhole control device corrects deviations between the reference trajectory and the actual trajectory more frequently than the downhole control device receives the reference trajectory from the uphole control device.

13. The drill control system of claim 1 , wherein the uphole control device is in communication with a remote location via satellite.