Downhole tools and methods of controlling downhole tools

Abstract

A downhole tool that has a plurality of arm assemblies. Each of the arm assemblies has an arm configured to expand and retract and an actuator. A hydraulic bus in fluid communication with the plurality of arm assemblies. A plurality of flow control devices. The flow control devices are configured to selectively isolate one or more arm assemblies of the plurality of arm assemblies from the hydraulic bus while maintaining the other arm assemblies of the plurality of arm assemblies in communication with the hydraulic bus.

What is claimed is: 
     
         1 . A downhole tool comprising:
 a plurality of arm assemblies, wherein each of the arm assemblies comprises an arm configured to expand and retract and an actuator, and wherein the arm assemblies are configured to be independently actuated.   
     
     
         2 . The downhole tool of  claim 1 , wherein the plurality of arm assemblies comprises a first arm assembly and a second arm assembly. 
     
     
         3 . The downhole tool of  claim 2 , wherein the first arm assembly comprises a first arm and a first actuator, and wherein the second arm assembly comprises a second arm and a second actuator. 
     
     
         4 . The downhole tool of  claim 3 , wherein a plurality of flow control devices comprises a first flow control device located between a hydraulic bus and the first actuator and a second flow control device between the hydraulic bus and the second actuator. 
     
     
         5 . The downhole tool of  claim 4 , further comprising a control module in communication with the plurality of flow control devices and at least one sensor. 
     
     
         6 . The downhole tool of  claim 1 , further comprising a control module in communication with a plurality of flow control devices and at least one sensor, wherein the control module is configured to control the plurality of flow control devices to selectively isolate the plurality of arm assemblies from the hydraulic bus based on data acquired by the at least one sensor. 
     
     
         7 . The downhole tool of  claim 1 , wherein each of the arm assemblies of the plurality of arm assemblies comprises a constant force actuator connected with the actuator. 
     
     
         8 . A method of controlling arm activation of a downhole tool, wherein the method comprises:
 providing fluid to a hydraulic bus in fluid communication with a plurality of arm assemblies; and   isolating one or more arm assemblies of the plurality of arm assemblies from the hydraulic bus while maintaining the other arm assemblies of the plurality of arm assemblies in communication with the hydraulic bus.   
     
     
         9 . The method of  claim 8 , wherein isolating comprises closing one or more flow control devices. 
     
     
         10 . The method of  claim 8 , wherein the one or more arm assemblies of the plurality of arm assemblies are isolated from the hydraulic bus in response to data acquired by a sensor in communication with a control module. 
     
     
         11 . A downhole tool comprising:
 a plurality of arm assemblies, wherein each of the arm assemblies comprises an arm configured to expand and retract and an actuator, and wherein the arm assemblies are configured to be independently actuated;   a control module for selectively actuating the plurality of arm assemblies; and   a sensor in communication with the control module.   
     
     
         12 . The downhole tool of  claim 11 , wherein the plurality of arm assemblies comprises a first arm assembly and a second arm assembly. 
     
     
         13 . The downhole tool of  claim 12 , wherein the first arm assembly comprises a first arm and a first actuator, and wherein the second arm assembly comprises a second arm and a second actuator. 
     
     
         14 . The downhole tool of  claim 13 , wherein a plurality of flow control devices comprises a first flow control device located between a hydraulic bus and the first actuator and a second flow control device between the hydraulic bus and the second actuator. 
     
     
         15 . The downhole tool of  claim 14 , wherein each of the actuator is a constant force actuator. 
     
     
         16 . The downhole tool of  claim 15 , wherein the constant force actuator comprises an arm, a fixed support, and a slider. 
     
     
         17 . The downhole tool  claim 11 , wherein a constant force actuator is connected with the downhole tool, and wherein the constant force actuator comprises: a plurality of arms, a slider, a plurality of movable supports, and a fixed support. 
     
     
         18 . The downhole tool of  claim 17 , wherein the constant force actuator comprises a bar connecting a first arm of the plurality of arms with a second arm of the plurality of arms. 
     
     
         19 . The downhole tool of  claim 17 , wherein the constant force actuator is a centralizer, caliper, or anchor.