X20 system modules • Motor controllers • X20SM1436
2050
X20 system User's Manual 3.10
Mixed decay threshold
By default, mixed decay is always enabled (mixed decay threshold = 15).
A self-stabilizing control loop in the current controller results in an optimal, sinusoidal current flow. This ensures a
high level of positioning precision and low motor resonance, especially at low speeds.
Mixed decay interferes with reliable stall detection. If stall detection is used (e.g. during homing), mixed decay
should be disabled (mixed decay threshold = 0).
Relationship between stall detection and mixed decay
Depending on the application and the motor used, satisfactorily smooth operation can be achieved while using
stall detection by setting the mixed decay threshold to a value between 1 and 14. This is a compromise between
smooth operation and stall detection quality and must be fine tuned during commissioning.
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Mixed decay threshold
Mixed decay
Stall detection
Stall threshold
The SM module features integrated sensorless load measurement for the motor axis. This is especially useful for
detecting a "stall condition" (e.g. if the motor moves to the end point during a homing procedure). It cannot be used
for torque monitoring during dynamic movements.
The "stall threshold" (bits 4 to 6 of this register) can be used to define a threshold value for each axis individually
according to the motor load, beyond which the motor will detect a stall condition.
This threshold value must be determined on a case-by-case basis, since the results of load measurement are
influenced by a variety of factors.
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Motor speed: A higher speed results in higher measurement values
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Speeds that cause motor resonances (which interfere with load measurement) are to be avoided
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Motor accelerations that create a dynamic load (and also affect the measurement) should also be avoided
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It is especially important to be aware that mixed decay mode must be disabled or optimized for reliable
stall detection
The higher the load measurement value, the lower the load. That means: A stall condition is detected if the load
measurement value drops below the trigger threshold for stall detection.
Summary of Contents for X20 System
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