要求：a、试确定一个状态反馈阵K，使相对于单位阶跃参考输入的输出过渡过程，满足如下的期望指标：超调量σ< 20 ,峰值时间t_p< 0.4s。

b、如果系统的状态变量在实际上无法测量，试确定一个状态观测器（全维），使得通过基于状态观测器的状态反馈，满足上述期望的性能指标。

-Requirements: a, a test to determine the state feedback matrix K, for the output of the phase transition process unit step reference input, to meet the expectations of the following indicators: overshoot σ <　 20 , peak time t_p <　 0.4s. b, if in fact the system state variables can not be measured, determine a state observer (full-dimensional), so that by the state observer based state feedback, satisfying the above desired performance metrics.