启用校正模式
应用中CORRECTING和REPOSITION模式下默认动作可以按以下某一个值设定STCORRECT参数来配置：
•STCORRECT=-1（约束）（缺省）
当应用处于TEST或TEST-NOPULSE模式时不会自动调用CORRECTING或REPOSITION模式。
与多测试(Multi-Test)模式一样，当CV违反约束后，必要的违反约束校正动作将会自动进行。然而，TEST或TESTNOPULSE将继续。
•STCORRECT=0（复位）
当CV违反约束时应用将调用复位(REPOSITION)模式。
•STCORRECT= 1（校正）
当CV违反约束时应用将调用校正(CORRECTING)模式。如果违反约束持续一定时间，即使运行在校正模式后，它也会重新进入复位模式。

概要
CORRECTING模式用于驱动过程在约束范围内，使得阶跃测试可能得到恢复。在TEST, TEST-NOPULSE或SUSPEND模式下，当CV违反约束且最大数量校正动作（STCMFLAG）已经应用后其将触发。当CORRECTING模式被触发时，当前的MV阶跃测试将被中断，测试组的独立DMCplus控制动作将被激活。在CORRECTING模式时，MVs通过类阶跃动作将违反约束CVs带回测试边界限。系统将尝试保持阶跃状态MV，使得即使有类似中断当前阶跃依旧可以计数。对于斜坡CV，它将尝试在最接近极限的里面，而不是测试极限中间返回一个测试裕度。测试组的CORRECTING模式将至少持续STREPOMIN × SSMINS分钟。但如果处于CORRECTING模式长于STREPOMAX× SSMINS而CVs依然处于违反约束状态，则系统将激活REPOSITION模式（使用连续控制动作）。
CORRECTING模式遵循以下规则：
•当CV超过测试限（STCVMIN和STCVMAX）外STCVDELTA时应用将触发CORRECTING模式。
•至少经过指定的STREPOMAX× SSMINS时间后应用才将触发CORRECTING模式。在STREPOMIN× SSMINS时间后如果所有的CVs都距测试限内至少1/2STCVDELTA则该组将恢复测试。
•在STREPOMAX× SSMINS时间后，如果所有的CVs都在测试限内，则该组将继续测试。对于斜坡CV，除了在测试限之内，斜率也必须小于STRAMPRT。如果CVs不在测试限内，或斜坡变量不满足斜率准则，则将触发REPOSITION模式。
当处于CORRECTING模式时，离散动作解决方案是基于相关CV测试裕度（STCVDELTA）和模型增益（测试裕度越大，解决方案动作越大）计算。

避免CORRECTING和REPOSITION模式
尽管一些CORRECTING, REPOSTION和CONTROL模式的数据也可用于模型识别，测试过程中一个主要目标是限制应用处于CORRECTING或REPOSITION模式的时间。在不违反最大MV阶跃大小和CV测试限的前提下，智能向导引擎所使用的阶跃大小算法将尽可能尝试最大的阶跃输出。鉴于各种不确定性，若CV违反约束，测试人员依然可以进入CORRECTING或REPOSITION模式。测试人员是不断将过程推向测试限的，但由于可能使用较差的模型，它会经常对限制响应过量或不足。

整定以避免CORRECTING或REPOSITION模式包括以下内容：
•设置适当的测试限(STCVMIN和STCVMAX)。限制应设置成假设它们很可能被侵犯。
•CV安全裕度(STCVDELTA)是一个指示触发REPOSITION模式前超出限制容忍量的整定参数。
•在测试模式中，STSTEPFRAC是一个影响所有MV阶跃大小的全局参数。它反映了你对模型的信心，以及可以用来避免过多的违反约束。
在测试中一个好的策略是将界限和安全裕度设置在合理的值，然后使用STSTEPFRAC参数尽快动作。随着新的，改进的模型被投用，测试中可以通过增加STSTEPFRAC来最大化阶跃尺度。

也可以看看
智能向导应用中的REPOSITION(复位)模式
智能向导应用中的校正动作
智能向导应用中的参数整定

附原文：
Enabling CORRECTING mode
The default CORRECTING and REPOSITION mode behavior for an application can be configured by setting the STCORRECT parameter to one of the following values:
•STCORRECT = – 1 (CONSTRAINT) (default)
No CORRECTING or REPOSITION mode will be invoked automatically when the application is in TEST or TEST-NOPULSE mode.
The necessary violation correction moves will be made automatically whenever CV violates, just like in Multi-Test mode. However, the TEST or TESTNOPULSE will continue on.
•STCORRECT = 0 (REPOSITION)
The application will invoke REPOSITION mode when CV violation happens.
•STCORRECT = 1 (CORRECTING)
The application will invoke CORRECTING mode when CV violation happens. If the violation persists for a certain time period, even after running in CORRECTING mode, it will fall into REPOSITION mode.

**Overview **
CORRECTING mode is used to drive the process within constraints so that step testing may resume. It is triggered from TEST, TEST-NOPULSE or SUSPEND modes when a CV violates the constraint and the maximum number of correcting moves (STCMFLAG) has already been applied. When CORRECTING mode is triggered, the current MV step test is interrupted, and a discrete DMCplus control action is activated for the test group. During CORRECTING mode, the MVs make step-like moves to bring violating CV(s) back one test margin inside the limits. An attempt is made to keep the stepping MV where it was, so the current step can still be counted even with this interruption. For a ramp CV, it attempts to return it one test margin inside the closest limit, instead of the middle of the test limits. A test group stays in CORRECTING mode for at least STREPOMIN × SSMINS minutes long. But if it is in CORRECTING mode longer than STREPOMAX × SSMINS with CV(s) still violating their constraints, then REPOSITION mode is activated (using continuous control action).

CORRECTING mode is governed by the following rules:
•CORRECTING mode is triggered by a CV that is more than STCVDELTA outside of its test limits (STCVMIN and STCVMAX).
•CORRECTING mode is triggered for a minimum of time specified by STREPOMAX×SSMINS. After STREPOMIN×SSMINS if all of the CVs are at least ½ STCVDELTA inside the test limits then the group will resume testing.
•After STREPOMAX×SSMINS, if all the CVs are inside the test limits then the group will resume testing. In addition to being inside test limits ramp CVs must have a ramp rate that is less than STRAMPRT. If the CVs are not inside the test limits or the ramps don’t satisfy the rate criteria then REPOSITION mode will be triggered.
When in CORRECTING mode, the discrete move resolution is calculated based on the associated CV test margin (STCVDELTA) and the model gains (the bigger the test margin, the bigger the move resolution).

Avoiding CORRECTING and REPOSITION mode
Although some CORRECTING, REPOSTION and CONTROL mode data can be used for identification, a major goal during testing is to limit the amount of time the application spends in CORRECTING or REPOSITION mode. The step size algorithms used by the SmartStep engine will try to make the largest step that does not violate either the maximum MV step size or any CV test limits. Because of various uncertainties, the tester may still enter CORRECTING or REPOSITION mode due to CV limit violations. The tester is constantly pushing the process toward test limits, but since it is using potentially poor models, it will frequently overshoot or undershoot the limits.

Tuning to avoid CORRECTING or REPOSITION mode includes the following:
•Setting the test limits appropriately (STCVMIN and STCVMAX). The limits should be set with the assumption that they will likely be violated.
•The CV Safety Margin (STCVDELTA) is the tuning parameter that indicates how much overshooting of the limits will be tolerated before triggering REPOSITION mode.
•STSTEPFRAC is the overall parameter that affects all MV step sizes in test mode. It reflects a confidence in your models, and it can be used to avoid excessive constraint violation.
A good strategy is to set the limits and the safety margins to reasonable values, and then use the STSTEPFRAC parameters to temper moves early in the test. As new, improved models are brought online, STSTEPFRAC can be increased to maximize the step size used during the test.

See Also
REPOSITION mode in a SmartStep application
Correcting moves in a SmartStep application
Tuning parameters in a SmartStep application

2015/10/27