说明：  函数再现机构设计 试设计一曲柄摇杆机构，再现函数 要求： 输入构件的转角范围180°，输出构件摆角范围30°，即： 当输入构件从a转至a+90时，输出构件从b转至b+30 当输入构件从a+90转至a+180时，输出构件从b+30转至b
(Function reproduce the design of mechanism design test one crank-rocker mechanism, reproduction function requirements: the corner of the scope of the importation of component 180 °, the output component swinging angle range 30 °, namely: When the input from a component to a+ 90, the output components from the b Go to b+ 30, when the importation of components from a+ 90 to a+ 180, the output component from b+ 30 to b)