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Instantaneous mode switching may help clean transitions between totally different servo motor management modes in advanced movement functions.
In closed-loop servo management programs, there are three important management modes, torque, pace, and place. Every of those parameters could 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 throughout the identical movement operation.
In most conventional servo management programs, 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 problems for designs that require utilizing a number of management modes with out interruption.
Instantaneous mode switching
One resolution 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 handbook mode and computerized mode in proportional integral spinoff (PID) management, it may be used equally in servo motor management.
The suggestions of all management alerts is continually monitored to develop the nested loop management construction of most of these servo motors and controllers. Usually, solely one of many three management loops is related to the output sign; nonetheless, unconnected management loops also can 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 gives benefits which might be extremely related in numerous functions, notably in fields that contain industrial automation, management programs, 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 total motion-related course of effectivity.
The advantages of instantaneous mode switching embody:
- 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 further flexibility and performance to deploy superior management algorithms for functions.
- Helpful in haptic power suggestions management schemes.
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Connotations and comparability metrics
The present in motor windings is usually accountable 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 accountable for torque technology. The maximized Q-axis present (IQ) is perpendicular to the rotor pole axis and is accountable for torque technology within the motor.
FOC with triple cascade loop management is the muse for seamless mode switching in motor management. In a triple cascade loop configuration, every loop is accountable for regulating totally different elements of the system corresponding to present, pace, and place. The output of 1 loop is used because the setpoint for one more 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 help consider the motor’s seamless mode-switching efficiency.
With instantaneous mode switching, the motor begins in pace management mode with a goal pace 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 pace at 1,000 rpm. After a couple 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 pace of three,000 rpm.
As Determine 2 exhibits, there aren’t any bumps and spikes noticed within the IQ sign throughout mode switching, and the respective management output alerts are appropriately managed to the reference alerts after switching. Because of instantaneous mode switching, the motor is bodily steady with no shaking or bouncing behaviors noticed. As 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 utility examples
A couple 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 power. In most of these functions, the servo can function in place management mode to align the half, then change to torque mode to use the suitable mechanical insertion power. 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 utility, 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 power.
Automated centrifuge programs
Centrifuge programs use centrifugal power to separate liquid, gasoline, and strong substances based mostly on their density. Automated centrifuge functions work together with pick-and-place machines, requiring exact pace management throughout the centrifuge course of and correct place management to cease. Throughout the centrifuge separation course of, the rotor holding the samples spins at a set pace 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) programs for wafers
Spin rinse dryers (SRDs) clear and dry semiconductor wafers in a collection of cycles that embody 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 accountable for the spinning movement within the wafer cleansing course of. The rinse, purge, and dry cycles are pushed in pace 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 pace and place management modes to realize the SRD course of in a single-motion operation.
Editor’s Observe: This text was syndicated from our sister web site Movement Management Suggestions.
