View Full Version : Servo Stats Confusing

03-01-2007, 11:10 PM
Dear Trossen Folk,

I'm interested in getting the PhidgetServo 4-Motor, and so I was reading the stats for the Hitec Servo HS322, which comes with the full kit. Unfortunately, many of the stats don't make any sense to me. For example:

Operating Angle: 40 Deg. one side pulse traveling 400usec
Direction: Clockwise/Pulse Traveling 1500 to 1900usec

I'm afraid I can't tell from this what the actual rotational range of these servos are. Could you please help translate for a neophyte?

Also, if I want the servo to rotate very slowly -- say, 6rpm or so -- does it work to simply send a series of slightly different position settings slowly over time? Or would that result in jerky movement of the servo?

Thanks very much for your help!

03-08-2007, 03:39 PM
Hey Clavis,

Depending on which servo, generally speaking servos have a range around 180°, meaning they continuously turn. The HS322 in particular has a range of around 210°.

If you want continuous:

However, then you lose positioning. You can't have both.

04-23-2007, 11:02 AM
I had a long conversation about this with someone at Trossen last week. My understanding is that if you want a motor that can do 360 and you want control over its positioning you have to buy a motor and then an encoder that track the motors rotation and tells the computer how far it has turned.

The hardware I was recommended was the following (prices approximate)

- Phidgets Servo 1 motor [$29]
- Banebotts DC controller (to run the motor) [$30]
- Banebots motor (in the robotics section) [~$30]
NOTE: make sure to get a motor that matches your controller specs. Also note that the motors are not plug and play like the phidgets gear. REead the info sheet to figure out what other stuff you will need. Also note that the motor appears to require a slight modification to prevent interference with electronics if this is an issue for you.

- Phidgets High speed encoder [$55]
- Banebots encoder [$38]

Total cost is about $200 for all these parts

How it works (as far as I understand it) -- the encoder reads the motion of the motor and reports it via the phidgets encoder to the computer. The phidgets servo controller runs the motor and turns it on long enough to move it the amount you want.

Disclaimer -- I'm only reporting what I was told by the guy on the phone, so I can't vouch for the accuracy of all this. For instance I don't know how precisely the Phidgets servo controller can control the turning of the motor. The person I spoke to recommended that I speak with Dave if I wanted more info on the motors.

Good luck -- if anyone figures out a good solution to this please post!


06-22-2007, 04:27 PM
With the stats given is there any way we can calculate the rotational range of other servos? I tried to conjure 210 degrees from the HS322 stats but had no luck. I also looked on the HiTec website but couldn't find much for stats at all.

If the answer is no then I'd like to know what the rotational range of the HS5645 is, please.

Thanks! :)

06-26-2007, 09:31 AM
Sorry for taking so long Bill. I answered your question here:


Unfortunately, with the stats given there isn't any way that I'm aware of that allows us to calculate the range. We usually just eyeball them.

06-26-2007, 10:31 AM
No need to apologize. :) Thanks for the info.