are collapsed 332 advantageously embodiments of the present disclosure may provide a drilling apparatus capable of adapting to real time information provided by the weight sensors as to the hardness of the formation as previously described prior art cutter blocks require that formation intervals with a particularly increased hardness be identified before beginning the drilling operation this can be characterized as an u201c open loop u201d system because the initial formation data is the only information available once drilling starts open loop systems are hindered by a change in plans i e drilling in a direction not previously foreseen and are unable to adapt on the fly these limitations add considerable cost to the operation both in prep work prior to drilling and in contingency costs if the drilling operation deviates from the original plan in contrast the embodiments disclosed herein provide a closed loop system that continuously receives feedback on the current properties of the formation i e the formation hardness as drilling progresses this eliminates the need for a preliminary u201c mapping u201d operation to find intervals with increased hardness additionally a deviation in the drilling operation is easily accommodated because of the closed loop system 39 s ability to provide feedback on the most current formation conditions costs may be drastically reduced and conveyed to the customer further embodiments disclosed herein provide a drilling apparatus capable of maintaining a more constant rate of penetration u201c rop u201d regardless of the hardness of the material through which the drilling apparatus is passing with only one set of cutter blocks often the rop must be decreased in harder material to reduce premature wear of the cutters.