I'm currently researching a way to build a punch imitation (for boxing training) and for this i need a simple, fast (if it can be configurable great) and long linear motion which can handle a resistance (if the punch land on someone's face).

The things that I found which are similar to what I'm looking for are: solenoid (which, from what I heard have limitation when it comes to size) and a linear actuator (which is kind of slow from what I saw in couple of videos).

I'm really inexperienced when it comes to physics and hardware, so I need some kind of advice on what tools to research (mechanic parts and hardware) and for what to look for in general. Any help will be appreciated!

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    \$\begingroup\$ This sounds much more like a mechanical problem than electroinc. A hydraulic or pneumatic cyclinder might work... \$\endgroup\$ – Peter Bennett Mar 27 '17 at 22:37
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    \$\begingroup\$ I'm voting to close this question as off-topic because it is not about electronic design. \$\endgroup\$ – Chris Stratton Mar 27 '17 at 22:56
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    \$\begingroup\$ Same, but yeah I would go pneumatic, it's faster than hydraulic and you can vary the speed and and force somewhat separately with some clever regulation. \$\endgroup\$ – TWiz Mar 27 '17 at 23:19
  • \$\begingroup\$ I don't think everything is off topic, cause it is still dark matter to me how to control it electronically (if it is even possible) and what piece of hardware I need. \$\endgroup\$ – antonionikolov Mar 28 '17 at 11:40

First, while a solenoid is fast, they only come in short stroke lengths (much shorter than 23") and can overheat if held under load for extended periods of time. Second, while motor-driven linear actuators do come in long lengths, they are (as you mentioned) fairly slow.

Thus, the best linear actuator for your situation would be a pneumatic cylinder. They come in long lengths and can be driven very fast. There is also no risk of overheating if held under load. By adjusting the air pressure used to actuate it, you could also modify its striking force. The supplier McMaster-Carr carries a wide variety of pneumatic devices and accessories (along with pretty much everything else you can think of).

Here are some 24" pneumatic cylinders: https://www.mcmaster.com/#standard-air-cylinders/=16y0mff

You will also need solenoid valves to allow air into and out of the cylinder, as well as relays to control the solenoids.

Obviously, you will also need an air compressor and pneumatic tubing, which are probably the easiest of these parts to find.

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  • \$\begingroup\$ Motor driving a rotating nut in a screw thread - effectively a rotary to linear gearbox. Stroke is as long as you make the threaded rod (within sensible limits). You don't say what mass to be driven, acceleration rate, peak velocity and more. If say 1 kg and accelerating over 500 mm and you want a velocity of say 10 m/s (36 kph) at the end: Energy = 0.5 x m x V^2 = 50 Joules. From these you can calculate peak drive power, time of travel ... \$\endgroup\$ – Russell McMahon Mar 28 '17 at 7:22

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