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Servo motor Specification


I am designing a pan tilt system and i have torque and speed requirements for both pan and tilt motors. I am planing to use “FEETECH Ultra-High-Torque, High-Voltage Digital Giant Servo FT5335M” ( https://www.pololu.com/product/3429 servo) for both pan and tilt. Since pan tilt system will be used for tracking application, where can i find torque versus speed graph for same servo? So that i can match it with my required torque vs speed requirement for this pan tilt system.

Thank you.


Hello, Amaresh.

I moved your post to a more appropriate section of the forums.

We do not have a speed vs torque curve for those servos, but the slope of speed vs torque curve can be approximated as a linear relationship between zero torque at the no load speed and the peak stall torque at zero speed. So, you should be able to extrapolate to approximate the maximum speed at various loads. You can find those specifications in the datasheet for these servos under the Resources tab on the products web page.



Thank you DanM.
One more question, dont we have to match the inertia of load and motor? I saw posts over internet which mention to keep inertia ratio(Motor:load) within 1:5 for better performance. Here i dont find any servo specify the motor inertia.
Thank you.



I am not familiar with that rule of thumb (and I’m a little skeptical of it). Can you provide some links to those posts about it?

In general, hobby servo manufacturers do not provide detailed specifications like the inertia of the motor, and all of the information we have about that servo is in the datasheet. It seems like that rule might be intended to ensure quick servo movements. You could probably use the peak stall torque with the moment of inertia of your load to get a rough estimate of the peak angular acceleration of your load with the servo.



I was referring to this.


A servomotor is not the same thing as a servo; you can read more about that in this post on our blog. The most notable difference in reference to the article you link to is that our servos all come with gearboxes. Also, it seems like the systems they are referring to are way more powerful than our hobby RC servos and general guidelines like that might not still be applicable with a large change in scale.



Thank you Nathan.
My application does not need high torque,only 0.01N-m (1.5 Kg load). So is it too much for FEETECH FS90 Micro Servo?


The FEETECH FS90 servo would probably be fine for a load that only needed 0.01N-m, but 0.01N-m seems like a really low torque for rotating an object weighing 1.5kg.