直达滑模控制

Direct reaching sliding mode control

用传统到达条件综合而成的滑模控制系统不能保证所有出发于滑动模态邻域的相轨线都能直接到达邻近的滑动模态分支,导致状态转移过程超调,这对于某些控制工程是不允许的.为使滑模控制过程单向收敛,提出了直达滑模控制方法.通过对传统到达条件表述中的不足的分析,介绍了直达函数的定义和直达条件的建立.直达条件是用直达滑模控制法综合滑模控制系统的依据.直达滑模控制系统由指令模态及开关型直达滑模控制组成.与传统到达条件不同,满足直达条件的控制,可保证所有出发于滑动模态邻域的相轨线都能直接到达邻近的滑动模态分支,沿滑动模态趋向零态,状态转移过程快速而无超调.将直达滑模控制应用于示例系统并进行仿真,仿真结果符合对直达滑模控制性能的预期.

Sliding mode control（SMC） system synthesized by traditional reaching condition can not grantee all phase trajectories from the neighborhood of the sliding mode to direct reach the nearby sliding mode branch.It will cause the state transition to be slow and overshooting which are not allowed in some engineering.In order to make the dynamic procedure of a SMC system unidirectional convergent,the direct-reaching SMC（DRSMC） was presented.By analyzing the shortcomings in the expression of traditional reaching condition,the definition of direct-reaching function and the establishment of direct-reaching condition were introduced.Direct-reaching condition（DRC） is the basis of using DRSMC to synthesize a SMC system.A DRSMC system is composed of a command mode model and an on-off type DRSMC model.Different from the traditional reaching condition,the control which satisfies the DRC can guarantee all phase trajectories from the neighborhood of sliding mode to direct reach the nearby branch of the sliding mode and then go to zero state.Therefore the state transition process will be fast and monotonous.The DRSMC was applied to an example system and was simulated.The simulation result accords with the performance expectation of DRSMC.