invalid use of non-static member function

## Problem description 
I used thread to separate  reading **imu** from **spinOnce**, but i met the compilation that
```
invalid use of non-static member function
```

## Solution 
write the code like this to initiate thread and it will work
```c++
std::thread t(&IOManager3::readIMU,this);//this line is in the IOManager3.cpp, readIMU is a member function of IOManager3
```