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I want to control a servo motor using Arduino and sensors. But all the example schemes or tutorials so far I found are for motors used in toys, low power applications. My task is to control a servo motor which can drive higher torques and lifts up to 100 kg. My concerns:

  1. Is the schematics and circuitry same with the RC motor examples or one should use extra circuitry such as power amplifiers for big motors?
  2. How to choose the proper type of motor for my task?
  3. Is there any reference to learn more about Arduino control of motors used in industry or more powerful applications?
m.Alin
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user16307
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    The principle for small or large motors is the same the difference is that large motors use higher lvls of voltages and currents so you will need power transistors. – Alberto Bonsanto Nov 25 '12 at 12:02
  • which kind of control? you need to control speed or just on/off? – Felice Pollano Nov 26 '12 at 11:19
  • i want to control the height of a weight from a sensor. for example if the temp is 20 C it will be at 50 cm and if it is 25 C it will be at 60 cm. – user16307 Nov 26 '12 at 12:42
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    Industrial motor controls / servo mechanisms bear very little user-level similarity to RC "servos" - they are both closed loop systems but that's about all the similarity there is. – Chris Stratton Nov 26 '12 at 12:51

2 Answers2

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For industrial grade applications, a more typical arrangement than the conventional servomotor, is a suitably geared down 3 phase motor, with either end-stop detection, or some form of position encoding, controlled by a HVAC (or main line voltage) control circuit, either switched or PID based.

For instance, in railway locomotives, while the pantograph seems an ideal candidate for a big servomotor, that is rarely if ever the mechanism used for extension and retraction. Note also that pantographs are not always two-position, some designs have fairly sophisticated sensing mechanisms and fine position and pressure control.

Another typical actuation mechanism for the kind of motion you are describing is the use of pneumatics or hydraulics - you can see this in the lift arms of fire trucks, for instance, or as the actuators for garbage trucks. This prevalence of liquid / gas drives instead of electric motors is for at least a couple of reasons: Safety (electrical failures and fail-safe modes) and flexibility of power routing. It is easy to have a compressor far removed from the moving parts, and just use piping down to the actuator.

Again, there are a number of sensors involved, to ensure precise positioning with such actuators. This is either in position steps, or fully analog sensing. There are also usually independent channel end-stop sensors to account for catastrophic failures by engaging some sort of fail-safe. The positioning, either way, is via external feedback channels rather than the integrated model used in hobby servomotors.

Seemingly So
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  • While not so much applicable to lifting applications, there are however plenty of direct driver servomotor applications; especially things which require precise bidirectional positioning and so can't tolerate the backlash of most gear drives (though toothed belts sometimes are a tolerable form of reduction). Automated machine tools would be the classic example. Some of these do have screw-driven vertical axis. – Chris Stratton Nov 29 '12 at 22:28
  • Both of your "pneumatic" examples use hydraulics, not pneumatics. – markrages Nov 30 '12 at 21:17
  • @markrages Yes, you are right. – Seemingly So Dec 01 '12 at 05:48
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If you mean using on a real world industrial application you should read this question Reliability of the Arduino platform for industrial use. Otherwise driving a big engine is just a matter of designing the power stage of the driver. This is difficult "per-se" independently if you are using Arduino or something else.

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Felice Pollano
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