2-Axis System specification

[IRQ7]

I am creating the control system for a 2 axis system. The first axis is to travel 6 meters horizontally. It will carry the 2 axis a horizontal axis that will travel 3 meters. Overall the system should be able to cover a plane of 6x3 meter.

My idea is to use screw driven linear motion system for both axis. The axis system should be capable of carrying a 20kg load at about 1-1.5 m/sec.

I would like to use stepper motor to drive the linear motion systems but I have not dealt with such a big system that I am not sure how much load to expect.

So to my questions:

1. Is a screw driven/ball guided vertical axis linear motion system a good solution? Any specifics on what to watch for?
2. Is the vertical axis screw driven/ball guided the best solution as well.
3. What are the advantages of using say a belt drive system?
4. Are stepper motors ok or would it be best to use DC motors?

Thank you in advance on all the tips or advice you can provide.

 

[MintJulep]

1. If it meets all of your unidentified requirements yes.
2. If no other system is better suited to meet your unidentified requirements then yes.
3. A belt would likely be less expensive.
4. Stepper motors are generally DC.

 

[MikeHalloran]

That's pretty fast for a screw drive.
That's a very long screw; you would need to stabilize it at some intermediate points; see 'critical speed'.
It will require a big stepper; they get expensive with size.


How good do you need the positioning to be?
I'm thinking DC drives, steel cables, and some kind of position transducer to close the loop. Timing belts could work, but I don't think they come big enough to do the job without splices. Roller chains would be my second choice, at lower speeds; at the quoted speed, they'll need guidance and/or high tension.








Mike Halloran
Pembroke Pines, FL, USA

 

[IRQ7]

Mike thanks for the input,

The positioning is not that important, as it will be used in a similar fashion as a car wash system. It just needs to go back and forward up and down.

While the stepper motor is easy to control, I have not ruled out a regular geared DC motor. Nevertheless I am not sure how big will big be for such system in terms of say oz-in.

I was thinking on using a Thomson Linear system so I would not have to worry about stabilization.

Any links or recommendations for a steel cable type of solution?

 

[tygerdawg]

Your specification is missing the single most important piece of information: how fast do you need to accelerate those loads. THAT will determine how much torque you require, and that determines your motor choice. A fast accel/decel will require higher torque/larger motor.

You might be able to use a stepper, and integrating it would certainly be simpler. Another choice would be servos, but servos are typically pointed at higher-performance systems & applications. So the solutions are usually more pricey than simple steppers. But you can use the servo controller to do your control programming in many cases.

You certainly could use timing belts...if the environment wouldn't harm them. You can get endless belts or thermally spliced, no problem. And then you have the flexibility of putting in tensioners and also easy maintenance & repair.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[Occupant]

You could use Hybrid Stepping Motors. They are AC and relatively easy to control, but the resolution is maybe 200 steps (1.8 degrees) per rev. Is that acceptable?

 

[zekeman]

Rack and pinion drive with DC motor control
;motors mounted on mass.

However my first choice is belt dive with DC servomotor control.