Pipe traversing apparatus, sensing, and controls

Abstract

A system for detecting radial movement of a robotic apparatus on a pipe, comprising distance sensors configured to measure a distance between their respective fixed positions and a surface of the pipe, and a processor configured to detect a change and determine whether the change is indicative of radial movement. A system for tracking a position of a robotic apparatus on a pipe, comprising mirrored, freely-rotating mecanum wheels, a sensor(s) configured to measure rotation of the mecanum wheels, and a processor configured to calculate a linear displacement of each mecanum wheel and resulting axial and circumferential positions of the robotic apparatus. A method for navigating a bend or curve of a pipe, comprising generating computer models of the robotic apparatus and the pipe, performing a computer simulation to identify a combination of wheel speeds that keeps the wheels in constant contact with the pipe, and operating the wheels accordingly.

What is claimed is: 
     
         1 . A system for tracking a position of a robotic apparatus on a pipe, comprising:
 a robotic apparatus;   at least one optical flow sensor mounted on the robotic apparatus and configured to measure axial and circumferential translation of the robotic apparatus on the pipe; and   a processor configured to determine, based on the measured axial and circumferential translation, an axial and circumferential position of the robotic apparatus on the pipe.   
     
     
         2 . The system of  claim 1 , wherein the at least one optical flow sensor is configured to measure an apparent motion of a surface of the pipe within a field of view of the optical flow sensor. 
     
     
         3 . The system of  claim 2 , wherein measuring the apparent motion of the surface of the pipe is based on a distance between the optical flow sensor and the surface of the pipe, dimensions of the field of view of the optical flow sensor, and pixel displacement in the field of view of the optical flow sensor. 
     
     
         4 . The system of  claim 1 , wherein the at least one optical flow sensor is mounted on the robotic apparatus such that it remains at a fixed distance from the surface of the pipe. 
     
     
         5 . The system of  claim 1 ,
 wherein the at least one optical flow sensor is mounted at a first fixed position on the robotic apparatus, and   further comprising at least one distance sensor mounted at a second fixed position on the robotic apparatus and configured to measure a distance between the second fixed position and a surface of the pipe.   
     
     
         6 . The system of  claim 1 , wherein the axial translation and circumferential translation of the robotic apparatus on the pipe is determined as equal in magnitude and opposite in direction of the measured apparent motion of the surface of the pipe. 
     
     
         7 . The system of  claim 1 , wherein the processor is further configured to calculate, based on the axial translation and the circumferential translation of the robotic apparatus along the pipe and a diameter of the pipe, a relative position of the robotic apparatus on the pipe. 
     
     
         8 . The system of  claim 7 , wherein, in calculating the relative position of the robotic apparatus on the pipe, the processor uses the pipe diameter to convert the circumferential translation to angular position of the robotic apparatus on the pipe. 
     
     
         9 . The system of  claim 7 , further comprising at least one sensor configured to measure the diameter of the pipe, and wherein the processor uses the measured diameter of the pipe in calculating the relative position of the robotic apparatus on the pipe. 
     
     
         10 . The system of  claim 7 , wherein the diameter of the pipe is predetermined and stored in a memory accessed by the processor. 
     
     
         11 . The system of  claim 7 , wherein the processor is further configured to calculate an absolute position of the robotic apparatus on the pipe based on an absolute starting position from which the robotic apparatus began traversing the pipe, the relative position of the robotic apparatus on the pipe, and an absolute orientation of the pipe. 
     
     
         12 . A system for measuring a diameter of a pipe traversed by a robotic apparatus, comprising:
 a robotic apparatus;   a sensor coupled to the robotic apparatus at a fixed position and orientation and configured to measure a distance between the fixed position and a surface of the pipe when the robotic apparatus is coupled to the pipe; and   a processor configured to:
 calculate, based on a known geometry of the robotic apparatus, an expected vector between the sensor and the centerline of the pipe and an expected distance between the sensor and a centerline of the pipe; and 
 calculate a diameter of the pipe based on the measured distance, the expected vector, and the expected distance. 
   
     
     
         13 . The system of  claim 12 , wherein the sensor comprises a time-of-flight sensor. 
     
     
         14 . The system of  claim 12 , wherein the sensor comprises a capacitive displacement sensor. 
     
     
         15 . The system of  claim 12 , wherein the sensor is configured to measure a position of a contact member configured to physically contact the surface of the pipe relative to the fixed position. 
     
     
         16 . The system of  claim 15 ,
 wherein the contact member has a first end rotationally coupled to the robotic apparatus and a second end biased towards the surface of the pipe,   wherein the sensor is configured to measure a rotation angle of the contact member for use in calculating the distance between the fixed position and the surface of the pipe based on the measured rotation angle and a known length of the contact member.   
     
     
         17 . The system of  claim 15 ,
 wherein the sensor is oriented on the robotic apparatus to measure the distance between the fixed position and a surface of the pipe along the expected vector, and   wherein calculating the diameter of the pipe comprises subtracting the measured distance from the expected distance.   
     
     
         18 . A system for measuring a diameter of a pipe traversed by a robotic apparatus, comprising:
 a robotic apparatus comprising a first wheel configured for positioning on a first side of a pipe, a second wheel configured for positioning on a second, opposing side of the pipe, and a clamping member coupling the first wheel and the second wheel;   a sensor configured to measure a rotation of at least one element of the clamping member; and   a processor configured to calculate a diameter of the pipe based on the measured rotation and a known geometry of the robotic apparatus.   
     
     
         19 . The system of  claim 18 , wherein the sensor comprises a rotary encoder. 
     
     
         20 . The system of  claim 18 ,
 wherein the clamping member comprises an arm having a first end rotationally coupled to the first wheel and a second end rotationally coupled to the second wheel;   wherein the sensor is configured to measure the rotation of at least one of the first end and the second end; and   wherein calculating the diameter of the pipe is based on the measured rotation of the first end and/or second end and a length of the arm.