Selecting a servo to move back and forth by 10deg at 10 Hz


I have very limited experience with servos in general, so I am going to post a question that perhaps is quite obvious for many of you, but I do appreciate your help.

I need to select a servo that can travel 10 deg at 10 Hz back and forth for quite a long time. If I select from specs a servo that has a certain max speed for a full revolution can I assume that, without any load, that would be the max speed to travel only 10 deg continuously back and forth? Obviously, I have to consider the load and its inertia, but is there anything else I should keep in mind?
At the moment, I am looking at the DYNAMIXEL with embedded Encoder and I have a Dynamixel XH430-W210-R, which probably is not fast enough for my application (50rev/min at 12 V) but that I am testing using Labview. So far, using position control I managed to operate back and forth 10 deg at a maximum frequency of 2Hz.

Also, when looking at specs, what is the difference between rpm in Continuous Operation or Performance Characteristics?

Many thanks in advance for the help!

  1. Yes, you can assume (given tolerance for load and inertia) that the servo will move at it’s maximum rated speed within your 10 degree arc. A point of concern related to the inertia is that rapid directional changes place high instantaneous loads on the gear train, so wear and tear will be higher than expected and especially rapid or high inertia changes may trip safety overload sensors.
  2. DYNAMIXEL X servos have their maximum RPM and load rated according to their stall output. Long term operation at this maximum output will reduce the service life of the actuator significantly, ROBOTIS recommends that the majority of the actuator’s usage cycle should be under about 20% of the rated stall torque for maximum expected lifespan.

Hello there,

As you mentioned, the load and its inertia will significantly impact the performance of the servo. Make sure to calculate the total load on the servo and consider the torque requirements for your application.

Also in my opinion you should consider the ability of the servo to accelerate and decelerate quickly is crucial for achieving the desired frequency and motion profile. Check the servo’s acceleration and deceleration capabilities in the specifications.

Hope this will be helpful.