Optimizing controller parameters

It is advisable to optimize controller parameters with the maximum permissible load. Optimization with a smaller load may result in reduced cycle times. How-ever, no greater load can then be moved without first carrying out optimization again.

Detailed information about the oscilloscope is contained in the Oper-ating and Programming Instructions for System Integrators.

Step Optimization

1 $G_VEL_PTP, $G_VEL_CP

2 $I_VEL_PTP, $I_VEL_CP

3 $LG_PTP, $LG_CP

4 $RAISE_TIME

5 $RED_ACC_EMX

6 $DECEL_MB

7.4.2.1 Optimizing $G_VEL_PTP and $G_VEL_CP

Description The proportional component of the speed controller influences the dynamics of the velocity control.

 The higher the proportional component, the greater the reaction of the controller output to a new setpoint value.

 The higher the proportional component, the lower the following error.

 The higher the proportional component, the greater the current pulse height.

 If the control value is set too high, this causes the axis to overshoot and buzz.

 If the control value is set too low, this results in termination of the motion with an error message.

The aim of the optimization is to reduce the following error as far as possible without causing the axis to overshoot or buzz. The optimized value for

$G_VEL_PTP and $G_VEL_CP depends on the motor type, the size of the ki-nematic system and the maximum load to be moved.

Procedure 1. Set the integral component of the speed controller $I_VEL_PTP to a high value, e.g. 9,999, in order to deactivate its function.

2. Set the proportional component of the speed controller $G_VEL_PTP.

3. Increase or decrease $G_VEL_PTP in increments until dynamic control without current pulses and with a low following error is achieved.

4. Accept the optimized value for $G_VEL_CP.

Soft servo control

 Following error: 3.5 rad

 Current pulse height: 0.0 A

Suitable values for most kinematic systems range from 5 to 80. As a general rule, the values must be selected in the lower range for small motors and in the upper range for large motors. It is advisable to com-mence optimization with a medium start value.

Orientation value for the following error: approx. 1.0 rad

Fig. 7-2: $G_VEL_PTP=30

The value set for $G_VEL_PTP is too low. The following error is too great.

Hard servo control

 Following error: 0.9 rad

 Current pulse height: 10.0 A

The value set for $G_VEL_PTP is too great. The following error is low, but the current pulses are too strong.

Optimized servo control

 Following error: 1.3 rad

 Current pulse height: 4.0 A

7.4.2.2 Optimizing $I_VEL_PTP and $I_VEL_CP

Description The integral component of the speed controller influences the transient re-sponse of the axis to the nominal speed and stabilizes the control loop.

Fig. 7-3: $G_VEL_PTP=120

Fig. 7-4: $G_VEL_PTP=75

 The lower the integral component, the faster the reaction of the controller output to a new setpoint value.

 The higher the integral component, the greater the following error.

 The integral component has no effect on the current pulse height.

 If the control value is too low, this causes the axis to vibrate.

The aim of the optimization is to reduce the following error as far as possible without causing the axis to vibrate. The optimized value for $I_VEL_PTP and

$I_VEL_CP depends on the motor type, the size of the kinematic system and the maximum load to be moved.

Procedure 1. Set the integral component of the speed controller $I_VEL_PTP.

2. Increase or decrease $I_VEL_PTP in increments until fast servo control with a low following error is achieved and without the axis vibrating.

3. Accept the optimized value for $I_VEL_CP.

Slow servo control

 Following error: 1.7 rad

The value set for $I_VEL_PTP is too high. The following error is slightly too high and the servo control too slow.

Suitable values for most kinematic systems range from 40 to 800. As a general rule, the values must be selected in the lower range for small motors and in the upper range for large motors. It is advisable to commence optimization with a medium start value.

Orientation value for the following error: approx. 1.0 rad

Fig. 7-5: $I_VEL_PTP=999

Fast servo control

 Following error: 0.36 rad

The value set for $I_VEL_PTP is too low. The following error is low, but the servo control is too fast. The axis vibrates.

Optimized servo control

 Following error: 1.3 rad

7.4.2.3 Optimizing $LG_PTP and $LG_CP

Description The proportional component of the position controller influences the path-maintaining braking.

 The higher the proportional component, the greater the reaction of the controller output to a new setpoint value.

 The higher the proportional component, the lower the following error.

 The higher the proportional component, the greater the current pulse Fig. 7-6: $I_VEL_PTP=20

Fig. 7-7: $I_VEL_PTP=400

 If the control value is set too high, this causes the axis to overshoot and buzz.

The aim of the optimization is to reduce the following error as far as possible without causing the axis to overshoot or buzz. The optimized value for

$LG_PTP and $LG_CP depends on the motor type, the size of the kinematic system and the maximum load to be moved.

Procedure 1. Set the proportional component of the position controller $LG_PTP.

2. Increase or decrease $LG_PTP in increments until dynamic control with-out current pulses and with a low following error is achieved.

3. Accept the optimized value for $LG_CP.

Soft servo control

 Following error: 4.0 rad

 Current pulse height: 2.0 A

The value set for $LG_PTP is too low. The following error is too great.

Suitable values for most kinematic systems range from 0.2 to 0.8. As a general rule, the values must be selected in the upper range for small motors and in the lower range for large motors. It is advisable to commence optimization with a medium start value.

Orientation value for the following error: approx. 1.0 rad

Fig. 7-8: $LG_PTP=0.10

Hard servo control

 Following error: 0.9 rad

 Current pulse height: 10.0 A

The value set for $LG_PTP is too great. The following error is low, but the cur-rent pulses are too strong.

Optimized servo control

 Following error: 1.3 rad

 Current pulse height: 4.0 A