https://eishya-jin.link/2014/12/16/3-axis-brushless-gimbal%e3%81%ae%e4%bd%bf%e3%81%84%e6%89%8beiji%e3%81%95%e3%82%93%e3%81%ae%e5%8b%95%e7%94%bb%e7%b4%b9%e4%bb%8b/