Category:Servo Motors

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What is on this page

On this page it is described how a servo motor was modified to suit our purpose.


Servo Motor

On this wiki we will be using a AC servo motor, rated 2.8Kw. Although it is over rated for the Argon, it will be a good test to show how the Argon can behave in the control of such big motor. Motor is 13.9 Kg! Very high quality made by Siemens.


Servo original.JPG


Since the motor came with a non standard shaft termination, and it was required a shaft end with 14mm, so that it could be directly connected to the Alpha planetary reducer, the motor was fully disassembled so that we could get access to the rotor.


Disassemble of motor back (resolver)

This particular motor is fitted with a high quality resolver, as it can be seen on the following picture.

Servo resolver 1.jpg


and both the stator and rotor parts disassembled...


Servo resolver 2.jpg

Rotor before being machined

After fully disassembled, the rotor is fully shown. This servo also have a 24VDC brake, that can be clearly observed on the picture:

Servo motor rotor.jpg


Carefully, the rotor was protected with paper and tape, so that the rotor could be safely machining without chips getting into the magnets. After machined we tested it so see how did it fitted on the planetary reducer.


Rotor after being machined

After the shaft was machined:

Servo machined shaft.JPG


And testing on the planetary reducer before final set up.

Servo fit test planetary.JPG

Fully assembled motor

Finally the servo motor assembled:

Servo after shaft machined.JPG


Connecting the servo motor to the planetary reducer

Now it is time to create the flange between the motor and the planetary reducer. For this we have the help of the CAD, so time to draw.


Cad time.png


After, machining it (aluminium 15mm)

Milling servos adapters.jpg


After fully machined,

Servo adapters finished.JPG


They were mounted on the servo motor:

Servo with planetary 1.JPG

Servo with planetary 2.JPG


As a important side note, this motor, have a larger torque than the planetary reducer can handle. Since the torque that we will take from the motor can be controlled in the servo drive (and the servo drive cannot output the full 2.8Kw that the motor was designed for), the oversize motor will not damage the planetary reducer.

Servo motor fixing apparatus

A support needed to be produced, so that the motor+reducer can be correctly fixed to the remaining axis. This was made in such a way that both the motor body and the reducer are fixed as one, providing the best possible rigidity. The following images describe the work done.

Motor support milling.jpg

Finished motor support 1.jpg

Finished motor support 2.jpg

Finished motor and support.jpg


Mounted finished servo motor

And finally mounted on the axis:

Yaxis with motor 1.jpg

Yaxis with motor detail.jpg


Servo motor power plug

The servo motor plug contains the 3 phases (U,V,W) plus the brake connectors (24 VDC +,-) and finally a ground cable. All 6 cables are connected in the same servo power connector.

Servo power connector 1.JPG


After assembled and fitted to the motor plug:

Servo power connector 2.JPG


Servo motor resolver plug

The servo resolver plug have 12 connections. The following table shows the connections for the plug number, cable color and the connection on the Argon resolver.

Pin on plug# Description Cable color Argon resolver
1 Stator 2 + Yellow C+
2 Stator 2 - Green C-
3 Not used Not used -
4 Not used (reserved) white -
5 Not used (reserved) pink -
6 Not used Not used -
7 Rotor - Blue A-
8 Not used Not used -
9 Not used Not used -
10 Rotor + Red A+
11 Stator 1 + Gray B+
12 Stator 1 - Brown B-

Plug before fully enclosed (cable shield is wrapped around the back of the connector):

Servo resolver connector.JPG

Resolver and power connected

Servo power resolver connected.jpg

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