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Instantaneous mode switching may also help clean transitions between totally different servo motor management modes in advanced movement functions.
In closed-loop servo management techniques, there are three important management modes, torque, velocity, and place. Every of those parameters might be individually managed relying on the applying. Whereas a single management mode could also be sufficient for some functions, different extra superior functions might require a number of management modes inside the similar movement operation.
In most conventional servo management techniques, a given movement have to be accomplished earlier than switching between totally different management modes. In any other case, the drive sign might expertise a spike or important drop in winding present that may adversely have an effect on the efficiency of the movement profile. This creates issues for designs that require utilizing a number of management modes with out interruption.
Instantaneous mode switching
One answer to this problem is servo motors and controllers with instantaneous mode switching. These motors and controllers present instantaneous mode-switching functionality, enabling seamless switching between a number of management modes whereas the motor is in movement. Instantaneous mode switching may also be categorized as bumpless switching between servo management modes. Whereas bumpless switching usually applies to mode switching between guide mode and computerized mode in proportional integral spinoff (PID) management, it may be used equally in servo motor management.
The suggestions of all management indicators is continually monitored to develop the nested loop management construction of these kinds of servo motors and controllers. Sometimes, solely one of many three management loops is related to the output sign; nonetheless, unconnected management loops may develop as if they’re related to the output sign. Due to this fact, when switching between management modes, the motor can easily transition between totally different management loops with none jumps within the output management sign.
Benefits of instantaneous mode switching
Instantaneous mode switching offers benefits which might be extremely related in varied functions, significantly in fields that contain industrial automation, management techniques, and manufacturing. Sustaining steady and clean operation is significant for product high quality and consistency. These benefits assist keep away from disruptions that may have an effect on general motion-related course of effectivity.
The advantages of instantaneous mode switching embrace:
- Permitting for seamless transitions between all management modes.
- Preserving tuning and loop parameters throughout management mode switching.
- Offering excellent stability and efficiency throughout switching operations.
- Providing extra flexibility and performance to deploy superior management algorithms for functions.
- Helpful in haptic pressure suggestions management schemes.
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Connotations and comparability metrics
The present in motor windings is usually liable for torque technology and rotation. In three-phase field-oriented management (FOC), the three-phase motor system is simplified and reworked right into a two-axis direct-quadrature-zero (DQZ) transformation reference system. The minimized D-axis present (ID) is parallel to the rotor pole axis and isn’t liable for torque technology. The maximized Q-axis present (IQ) is perpendicular to the rotor pole axis and is liable for torque technology within the motor.
FOC with triple cascade loop management is the inspiration for seamless mode switching in motor management. In a triple cascade loop configuration, every loop is liable for regulating totally different features of the system equivalent to present, velocity, and place. The output of 1 loop is used because the setpoint for an additional loop, making a cascading impact.
IQ suggestions is a dependable indicator of the motor system’s efficiency and stability. Due to this fact, analyzing and evaluating IQ suggestions throughout mode switching may also help consider the motor’s seamless mode-switching efficiency.
With instantaneous mode switching, the motor begins in velocity management mode with a goal velocity of three,000 rpm and an acceleration of 10,000 rpm/sec. At 5 sec, the motor seamlessly switches to place management mode with the velocity at 1,000 rpm. After a number of seconds of working in place mode, the motor transitions to torque management mode with the goal torque set to twenty% of the motor’s nominal torque. Lastly, the motor switches again to hurry management mode with a goal velocity of three,000 rpm.
As Determine 2 exhibits, there are not any bumps and spikes noticed within the IQ sign throughout mode switching, and the respective management output indicators are appropriately managed to the reference indicators after switching. Because of instantaneous mode switching, the motor is bodily steady with no shaking or bouncing behaviors noticed. Compared, conventional motors that lack seamless mode switching capabilities shake or try to bounce off the bottom throughout precise operation mode switching. IQ spiking might set off a fault or safety, resulting in an abrupt pause in motor operation.
Some software examples
A number of examples illustrate how servo motors and controllers with instantaneous mode switching are utilized in functions requiring a couple of management mode.
Cobot with feeding or insertion functions
Feeding and insertion functions require a cobot to precisely place components and apply exact insertion pressure. In these kinds of functions, the servo can function in place management mode to align the half, then swap to torque mode to use the suitable mechanical insertion pressure. Seamless mode switching permits the cobot to easily transition between place and torque mode whereas sustaining stability and efficiency. For instance, take into account a plastic clip insertion software, the place the clip have to be seated at a set location and depth earlier than being pressed into the mating meeting with exact insertion pressure.
Automated centrifuge techniques
Centrifuge techniques use centrifugal pressure to separate liquid, fuel, and stable substances primarily based on their density. Automated centrifuge functions work together with pick-and-place machines, requiring exact velocity management through the centrifuge course of and correct place management to cease. In the course of the centrifuge separation course of, the rotor holding the samples spins at a set velocity for a given time, then seamlessly transitions to place mode. This stops the rotor on the goal place in a single-motion operation. The correct stopping place permits the pick-and-place robotic to load or switch samples to their designated areas.
Spin rinse dryer (SRD) techniques for wafers
Spin rinse dryers (SRDs) clear and dry semiconductor wafers in a sequence of cycles that embrace rinsing, purging, and drying the wafers. A cassette holding a rack of wafers is loaded into the rotor contained in the SRD chamber. This load-balanced rotor is liable for the spinning movement within the wafer cleansing course of. The rinse, purge, and dry cycles are pushed in velocity management mode for a set length at given speeds. After finishing all cycles, the rotor holding the wafers requires place management mode to cease in an upright place with out interruption. Instantaneous mode switching can allow seamless transition between velocity and place management modes to attain the SRD course of in a single-motion operation.
Editor’s Be aware: This text was syndicated from our sister website Movement Management Suggestions.