However, when the motor servo gearhead inertia is larger than the load inertia, the engine will require more power than is otherwise essential for this application. This improves costs because it requires spending more for a engine that’s larger than necessary, and because the increased power usage requires higher working costs. The solution is by using a gearhead to complement the inertia of the electric motor to the inertia of the load.
Recall that inertia is a measure of an object’s resistance to improve in its movement and is a function of the object’s mass and form. The greater an object’s inertia, the more torque is needed to accelerate or decelerate the object. This means that when the load inertia is much bigger than the electric motor inertia, sometimes it could cause extreme overshoot or increase settling times. Both circumstances can decrease production line throughput.
Inertia Matching: Today’s servo motors are producing more torque relative to frame size. That’s because of dense copper windings, light-weight materials, and high-energy magnets. This creates better inertial mismatches between servo motors and the loads they want to move. Utilizing a gearhead to better match the inertia of the motor to the inertia of the load allows for utilizing a smaller electric motor and outcomes in a far more responsive system that’s easier to tune. Again, this is accomplished through the gearhead’s ratio, where the reflected inertia of the load to the engine is decreased by 1/ratio^2.
As servo technology has evolved, with manufacturers producing smaller, yet better motors, gearheads have become increasingly essential companions in motion control. Locating the optimum pairing must take into account many engineering considerations.
So how will a gearhead start providing the power required by today’s more demanding applications? Well, that all goes back to the fundamentals of gears and their capability to alter the magnitude or path of an applied force.
The gears and number of teeth on each gear create a ratio. If a engine can generate 20 in-lbs. of torque, and a 10:1 ratio gearhead is attached to its result, the resulting torque can be close to 200 in-pounds. With the ongoing focus on developing smaller sized footprints for motors and the gear that they drive, the capability to pair a smaller electric motor with a gearhead to achieve the desired torque output is invaluable.
A motor could be rated at 2,000 rpm, but your application may only require 50 rpm. Attempting to run the motor at 50 rpm might not be optimal based on the following;
If you are operating at a very low acceleration, such as for example 50 rpm, as well as your motor feedback resolution isn’t high enough, the update rate of the electronic drive could cause a velocity ripple in the application. For instance, with a motor feedback resolution of 1 1,000 counts/rev you possess a measurable count at every 0.357 amount of shaft rotation. If the electronic drive you are using to control the motor includes a velocity loop of 0.125 milliseconds, it’ll look for that measurable count at every 0.0375 degree of shaft rotation at 50 rpm (300 deg/sec). When it generally does not see that count it will speed up the engine rotation to find it. At the quickness that it finds another measurable count the rpm will end up being too fast for the application form and the drive will slower the electric motor rpm back off to 50 rpm and then the complete process starts yet again. This constant increase and reduction in rpm is exactly what will trigger velocity ripple in an application.
A servo motor working at low rpm operates inefficiently. Eddy currents are loops of electrical current that are induced within the motor during procedure. The eddy currents in fact produce a drag force within the electric motor and will have a larger negative impact on motor performance at lower rpms.
An off-the-shelf motor’s parameters might not be ideally suitable for run at a minimal rpm. When a credit card applicatoin runs the aforementioned motor at 50 rpm, essentially it is not using most of its available rpm. As the voltage constant (V/Krpm) of the engine is set for an increased rpm, the torque constant (Nm/amp), which is certainly directly linked to it-can be lower than it needs to be. As a result the application needs more current to drive it than if the application had a motor particularly created for 50 rpm.
A gearheads ratio reduces the engine rpm, which explains why gearheads are occasionally called gear reducers. Using a gearhead with a 40:1 ratio, the engine rpm at the insight of the gearhead will be 2,000 rpm and the rpm at the result of the gearhead will be 50 rpm. Working the motor at the higher rpm will permit you to prevent the worries mentioned in bullets 1 and 2. For bullet 3, it allows the design to use less torque and current from the motor based on the mechanical benefit of the gearhead.