System and method for controlling a drilling machine

Abstract

A system and method for drilling a borehole using a drilling rig having a rotary drill bit includes monitoring one or more drilling parameters; determining whether the one or more monitored drilling parameters are within predetermined specifications for one or more of the monitored drill parameters; and, executing an exception control procedure for control of a drilling parameter. The exception control procedure receives an input sensor value associated with a drilling parameter and applies feedback control to establish a scaled error value that is used to compute a setting value for the drilling parameter. The drilling parameters controlled may include the rotation speed of the drill bit, the feed rate of the drill bit, the weight-on-bit, or rotation torque during retraction of the drill bit. A computer-readable database of specifications of drill bits may be provided as a part of the system.

I claim: 
     
         1 . A method for drilling a borehole using a drilling rig having at least one rotary drill bit, and a hoist actuator, the method comprising:
 executing a procedure to regulate the feed rate of the drill bit, the procedure comprising:
 executing a feed-rate regulation procedure; the feed-rate regulation procedure receiving a first input sensor value representing a currently-measured feed rate;
 the feed-rate regulation procedure further receiving target feed rate; 
 the feed-rate regulation procedure having an output; 
 scaling the output of the feed-rate regulation procedure by dividing the output of the feed-rate regulation procedure by the maximum feed-rate value for the drilling rig; and, 
 outputting the scaled value of the feed-rate regulation procedure as a command to the hoist actuator of the drilling rig. 
 
   
     
     
         2 . The method of  claim 1 , where the procedure to regulate the feed rate of the drill bit further comprises:
 executing an air-pressure exception control procedure and outputting from the air-pressure exception control procedure a command to reduce the drill bit feed-down rate when a predetermined jam prevention threshold is crossed; and,   executing an torque-retract exception control procedure and outputting from the torque-retract exception control procedure a command to reduce the drill bit feed-up rate when a predetermined jam prevention threshold is crossed.