# Measurement Method of Whole Mechanical Automatic Vertical Drilling Tools
## 2 Methods
### Measuring Object
The angular placement of the limiting slot is illustrated in Figure 3C-C. Lastly, Figure 3D-D displays the position diagram of both the upper and lower plate valves. The bias blocks can be classified according to different motion states. When the biased block is completely stable at a certain position, the state is recorded as State 1. When the biased block is not completely stable but always moves within a certain range and does not affect the normal operation of the drill, the state is recorded as State 2. When the partial block is completely unstable, or cannot be stabilized within a certain range, it is denoted as State 3. In State 3, the drill tool cannot be calibrated normally and \(\varphi\) continues to change irregularly. The angle of the final stable position of the eccentric block can be expressed as \(\varphi_{s}\), which is called the critical deflection angle. Because of the structure of the drill, \(\varphi_{s}\) cannot be eliminated, it can only be reduced. When the heavy block appears in State 1 or State 2, the LSR hardly pushes out, their \(F_{i}\) values appear periodically, and each \(F_{L}\) is very similar. The difference is that in State 1, the USR is pushed out almost continuously and the \(F\) of the USR appears periodically similar to \(F_{H}\). The TID consists of an eccentric block and an adjusting device, resulting in the N-MVDT having two eccentric blocks--the upper and lower eccentric blocks (the lower eccentric block is equivalent to the single eccentric block in the O-MVDT). For simplicity, we refer to the (lower) eccentric block as EB 1 and the upper eccentric block as EB 2. Moreover, the adjusting device mainly includes an internal cylinder valve, an external cylinder valve, and a turbine. EB 1 is fixedly connected to the upper plate valve; they continuously rotate when the wellbore is tilted and finally stop at a certain position. EB 2 exists in the low-resistance oil chamber, so its instantaneous position is very close to the theoretical lower side of the wellbore. When EB 1 and EB 2 rotate simultaneously, the angle between them is \(\varphi\). When they stop simultaneously, the angle between them is \(\varphi_{s}\). The TID can generate an additional torque to EB 1 in real time and in a closed loop by monitoring the change in \(\varphi\). This additional torque balances the resistance from the upper plate valve and ultimately reduces \(\varphi_{s}\). Afterward, EB 1 outputs more accurate inclination information to improve the inclination accuracy of the N-MVDT. Furthermore, EB 2 is attached to the internal cylinder valve, whereas EB 1 is securely fastened to the external cylinder valve. Consequently, \(\varphi\) represents the instantaneous angular deviation between these two valves. Both the internal and external cylinder valves incorporate numerous upper and lower orifices, designed strategically. As \(\varphi\) undergoes variation, it triggers an inverse adjustment in the flow areas of the upper and lower orifices. The upper orifices' flow area expands while the lower orifices' flow area contracts,  
Figure 3: Working principle of TID. (**A**-**A**) Detailed profile of the relative position of the upper orifice. (**B**-**B**) Detailed profile of the relative position of the lower orifice. (**C**-**C**) Angular placement of limiting slot. (**D**-**D**) Position diagram of the upper and lower plate valves. and the opposite holds true. The turbine, firmly affixed to the external cylinder valve, harnesses the torque it generates and transfers it to EB 1, thereby balancing the frictional torque effectively. When \(\varphi\) increases clockwise, the flux area of the upper orifices becomes larger and the flux area of the lower orifices becomes smaller. As a result, the drilling fluid flows more easily from the upper orifices, which then impacts the turbine to generate the adjusting torque [27]. After the adjusting torque is generated, it balances the friction torque on EB 1, causing \(\varphi\) to decrease.