反作用环

It is proved through the experimentation that adopting these technique can obviously improve the control precision of the reaction wheel's velocity and obviously minish the angle momentum output of the two-axis gimbals mechanism on the satellite.

结合反作用轮的控制模型，在双闭环控制结构上，加入了前馈控制和死区电压补偿。通过实验证明，采用这些技术，可以显著提高反作用轮转速的控制精度，大幅度减少星载二维转台的角动量输出。

On the basis of general double closed-loops PID position tracking design of theodilite, the step-by-step integral separate PID control method is introduced, the calculation shows that it can effectively restrain overshoot, track position smoothly, and is helpful to reaction wheel control.

在通常的经纬仪双闭环PID位置跟踪设计基础上，在位置环引入步进式积分分离PID控制策略，计算表明，其可以有效抑制超调，较为平缓的实现位置跟踪，利于反作用轮的角动量平衡作用。

Firstly, the control of reentry phase and the model of RCS jets are presented. Then the flight control system is divided into two subsystems based on the time-scale separation principle. The fast states subsystem corresponds to the three body-axis angular rates, the slow states subsystem controls the angle-of-attack, sideslip angle and the rate of the bank angle about the velocity vector. Lastly, the proportional-plus-integral feedback is designed to increase the system robustness.

首先，分析了SRLV再入段的数学模型，并给出了反作用推力控制系统的控制模型；其次，将非线性动态逆方法与时标分离原则相结合，考虑飞行器姿态控制系统的外环角回路的慢变特性和内环角速度回路的快变特性，独立设计了两个回路的控制律；最后，为了增强系统的鲁棒性，分别在两个回路中引入了比例－积分反馈，有效地抑制了干扰力、力矩和非线性对消带来的逆误差。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。