Patent ID: 7182154

Claim:
A directional borehole drilling system, comprising: a controllable drill bit, comprising: a plurality of leg assemblies mounted about a central axis, each of which includes a cone which rotates about a respective axle and thereby drills a borehole when said bit is driven to rotate about said central axis, each leg assembly attached to a common frame, at least one of said leg assemblies comprising: an upper leg which is mounted to a bit frame, a lower leg which is coupled to said upper leg, and a mechanism which, when actuated in response to a respective command signal, causes said lower leg to be translated with respect to said upper leg, thereby enabling said drill bit to preferentially bore in a desired direction, and instrumentation located near said bit which determines the error between the bit's present position and a desired trajectory and provides said command signals to said controllable drill bit such that said drill bit bores in the direction necessary to reduce said error.