说明：  用simulink中的SimMechanics模块搭建两关节机械臂模型，并用S-function函数编写控制程序，采用的是计算力矩法跟踪参考信号。
(SimMechanics module structures in simulink model of two-joint robot arm, and write control program, a function of the S-function is computed torque method tracks the reference signal.)