How many inventions does a patent involve? How to write a claim

In your case, my preliminary understanding is that the measuring mechanism you invented can cooperate with other actuators, and the actuator you invented can also be measured by other measuring mechanisms. In this case, you have to apply for two patents, one for protection measuring mechanism and the other for protection executing mechanism, and the whole device is generally unnecessary. If you think it is important, there are two ways to deal with it. One way is to protect in the above two patents, that is, to protect the measuring mechanism and its integral device, and to protect the actuator and its integral device, and the other way is to write a patent separately.