0x2013 Gain Scheduling

Depending on the application, the “optimal” tuning for the cascaded PID controller may differ between different operating points. If there is only one tuning available, it has to be a compromise not using the full potential of the hardware.

This feature allows the user to apply controller gains which will change dynamically regarding the current speed. This technique can be used within the cascaded position controller to compensate for nonlinear effects, especially stiction/friction in the mechanics. image/svg+xml

For velocities (in rpm) below a user-defined value, a set of PID values determined best for slow motion is used. Likewise, for velocities (in rpm) above a user-defined value, a set of PID values determined best for fast motion is used.

The PID values between these values are interpolated linearly.

 

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Name Index:Sub Type Bit Size Options Unit Access PDO Mapping
Enabled 0x2013:1 BOOL 1
Disabled 0
Enabled 1
readwrite

Enables or disables the gain scheduling feature.

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Threshold Velocity 0 0x2013:2 UDINT 32 0 0 readwrite

Velocity that determines the lower threshold. Underneath this value, controller gains set 0 is used. Beyond it, linear interpolation begins.

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Position Loop Kp 0 0x2013:3 REAL 32 0 0 readwrite

The P-gain of the Position Control Loop of area 0 (low velocity, below threshold velocity 0) [rpm/inc]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Position Loop Ki 0 0x2013:4 REAL 32 0 0 readwrite

The I-gain of the Position Control Loop of area 0 (low velocity, below threshold velocity 0) [rpm/(inc*s)]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Position Loop Kd 0 0x2013:5 REAL 32 0 0 readwrite

The D-gain of the Position Control Loop of area 0 (low velocity, below threshold velocity 0) [rpm*s/inc]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Position Loop Integral Limit 0 0x2013:6 UDINT 32 0 readwrite

The integrator limit of the Position Control Loop of area 0 (low velocity, below threshold velocity 0). The technique used for preventing the windup is clamping and it prevents the integral term from accumulating above or below pre-determined bounds. The limit should always be set in the driving shaft units, this is especially important when a gearbox is used in the setup.

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Velocity Loop Kp 0 0x2013:7 REAL 32 0 0 readwrite

The P-gain of the Velocity Control Loop of area 0 (low velocity, below threshold velocity 0) [mNm/rpm]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Velocity Loop Ki 0 0x2013:8 REAL 32 0 0 readwrite

The I-gain of the Velocity Control Loop of area 0 (low velocity, below threshold velocity 0) [mNm/(rpm*s)]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Velocity Loop Kd 0 0x2013:9 REAL 32 0 0 readwrite

The D-gain of the Velocity Control Loop of area 0 (low velocity, below threshold velocity 0) [rpm*s/inc]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Velocity Loop Integral Limit 0 0x2013:10 UDINT 32 0 readwrite

The integrator limit of the Velocity Control Loop of area 0 (low velocity, below threshold velocity 0). The technique used for preventing the windup is clamping and it prevents the integral term from accumulating above or below pre-determined bounds.

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Threshold Velocity 1 0x2013:11 UDINT 32 0 0 readwrite

Velocity that determines the upper threshold. Above this value, controller gains set 1 is used. Up to this velocity linear interpolation is performed.

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Position Loop Kp 1 0x2013:12 REAL 32 0 0 readwrite

The P-gain of the Position Control Loop of area 1 (high velocity, above threshold velocity 1) [rpm/inc]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Position Loop Ki 1 0x2013:13 REAL 32 0 0 readwrite

The I-gain of the Position Control Loop of area 1 (high velocity, above threshold velocity 1) [rpm/(inc*s)]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Position Loop Kd 1 0x2013:14 REAL 32 0 0 readwrite

The D-gain of the Position Control Loop of area 1 (high velocity, above threshold velocity 1) [rpm*s/inc]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Position Loop Integral Limit 1 0x2013:15 UDINT 32 0 readwrite

The integrator limit of the Position Control Loop of area 1 (high velocity, above threshold velocity 1). The technique used for preventing the windup is clamping and it prevents the integral term from accumulating above or below pre-determined bounds. The limit should always be set in the driving shaft units, this is especially important when a gearbox is used in the setup.

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Velocity Loop Kp 1 0x2013:16 REAL 32 0 0 readwrite

The P-gain of the Velocity Control Loop of area 1 (high velocity, above threshold velocity 1) [mNm/rpm]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Velocity Loop Ki 1 0x2013:17 REAL 32 0 0 readwrite

The I-gain of the Velocity Control Loop of area 1 (high velocity, above threshold velocity 1) [mNm/(rpm*s)]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Velocity Loop Kd 1 0x2013:18 REAL 32 0 0 readwrite

The D-gain of the Velocity Control Loop of area 1 (high velocity, above threshold velocity 1) [rpm*s/inc]

Name Index:Sub Type Bit Size Min Data Max Data Default Data Unit Access PDO Mapping
Velocity Loop Integral Limit 1 0x2013:19 UDINT 32 0 readwrite

The integrator limit of the Velocity Control Loop of area 1 (high velocity, above threshold velocity 1). The technique used for preventing the windup is clamping and it prevents the integral term from accumulating above or below pre-determined bounds.