CNC Brain is ready! 6-axis Double Closed Loop Controller
Originally posted back in April asking if anyone was interested in a 6-axis Double Closed Loop Controller (we had been using the system privately since Summer 2007). The response was great!
We have been humbled by the wealth of knowledge and wisdom. "Kind Thanks" to everyone that has made this possible.
Many of you have asked privately when the CNC Brain would be available. So, "Now" is a good answer. :)
www.CNCBrain.com
CNC Brain - $499
- 6 axis Double Closed Loop
- Automatic Error Recovery
- Runs under Windows via USB
- Includes software w/SDK/Source Code
You can see the ad here on CNC Zone.
Machine Growth/Correction
**Khalid,
First, the CNC Brain can run in three different modes:
1) Open Loop - no sensors
2) Closed Loop - with a sensor on the axis or ball screw for feedback
3) Double-Closed Loop - axis sensor and motor sensor both.
You can mix and match modes on the same machine so it can grow as your machine does.
As for axis sensors, there are several options. I'll try to post to the Safeguard forum this weekend in building a low cost linear scale. And a rotary scale for adding a 4th/5th/6th axis.
**Ger,
The stepper question is a great one! The CNC Brain is always watching the axis comparing theory to reality. It isn't a pulsiting engine, it is a motion control system. It watches everything in parallel. Imagine over 140 MPP processors (non-Von Neumann) doing all the motion control math for every axis, where is it going, and where it has been, nearly every clock ... and most of the MPP do several things at the same time.
In Closed Loop, the Brain becomes aware of a problem as it begins from the axis sensor (for example, with 5 micron scales, it will start preparing for correction, in case an error were to occur, within 10 micron). It then has a host of options (often, it corrects without you even noticing ... ball screw error, belt slippage, etc.), including decelerating the other axis in sync, then reaccelerating after the path is corrected ... automatically.
In Double Closed Loop, there is a pre-error condition. In other words, it compares the postion of the encoder and the position of the motor (with all vibrations and slippage ... steppers are never where they are thought) to get an idea of the strain the motor is under. This let's the Brain decide what is going on and begin correcting before the motor reaches a "breaking point".
The nasties of machining ... harmonics and rough spots ... are always going to occur. For example, the center of your mill has/will have less backlash and can run faster than the outer edges from wear. For fun, check your backlash at different position along the axis. :eek:
**Ger
That also reminds me. Need to post the BitSaver video. In BitSaver mode, if the spindle slows down, the motion control will slow down with it. Saves the bit in many cases. I'm not a good machinist. I **NEED** the machine to make up for my lack of skill.
Great questions!
s/Bruce
Quote:
Originally Posted by
ger21
If you have a stepper powered machine, and it stalls or starts losing steps, how do you correct the position, since the stepper has already run out of power?