2.PMAC Hardware-an example of a motion control system

There are many ways to make a motion control system, you can use embedded system, Special Motion Control PLC, Industrial computer + motion control card, special CNC device and so on. PMAC control is generally used in Industrial computer + motion Control Card (IPC) way, so that there are more flexible building systems, strong scalability and other advantages.

The following is a complete PMAC motion control System hardware composition and wiring and signal transmission .

The entire motion control system is based on the signal flow sequence and is composed of a motion module (limit sensor), Motor drive (encoder), motor driver----Pc->pmac card->PMAC Card Adapter plate . The red line in the figure is the signal transmission.

For a control system, there are two ways of driving circuit and control circuit .

In the figure, the driving circuit is mainly used to power the driver, after the output motor drive power to the motor to work properly, here the different drive requirements are not the same (220V or 380V), here in order to simply use 220V.

In the diagram, the control circuit mainly controls the entire system:

1. AC CONTACTOR control the main drive circuit through-off (can be used DC CONTACTOR 24V or AC contactor 220V, here with 220V)

2. Motor driver control circuit power supply (different drive requirements are not the same, DC 24V or AC 220V, here for simple use of 220V)

3. The adapter Board is powered (the transfer board is to divert the PMAC signal, can use the official adapter board or a self-designed adapter board, 220V output 15V to the adapter board power supply)

4. The limit sensor in the figure is powered, and the output 24V is supplied to the adapter board after 220V variable voltage. (This is only indicative, the actual signal line and the power supply line are from the adapter board line)

is a more figurative description of the entire system's composition:

The positive and negative limits in the figure are protected, and the 0 limit is used for the Encoder + lead screw module to find the origin point (because the encoder is generally incremental encoder, do not know their current position), if the grating ruler feedback can also use the mark origin of zero-back.

Note the motion module in the diagram, where the servo motor + encoder + Ball Screw module is used to form a semi-closed-loop system, or a linear motor + grating ruler (or servo motor + encoder + Ball Screw module + Grating ruler ) to form a fully closed-loop system.

If the ball screw module, need to understand the concept of lead , that is, the screw rotation of the module forward the distance, the common lead is 10mm,20mm.

If you are using a grating ruler for feedback, you need to understand the concept of grating scale resolution . The resolution of the grating ruler refers to the minimum length change which can be read and output by the grating ruler, the corresponding parameters are as follows: Grating number per millimeter, number of pulses, subdivision, etc. At present domestic grating scale resolution generally has 5μm, 1μm, 0.5μm, 0.2μm, 0.1μm. For example, 50-wire grating per millimeter, after 4 subdivision, can get a very simple 5μm resolution, as for the high-resolution grating ruler, it is necessary to use electronic subdivision technology.

Furthermore, the positioning accuracy and the repeatability of the whole module are simply the deviation range between the motion measurement results and the actual target instruction distance in the first position measurement, and the repeated positioning accuracy is the deviation range between the motion measurement results in the multiple position measurement.

The positioning accuracy and repeatability of the whole module are the factors we must consider when designing a motion control system, which is affected by many factors and must be considered carefully. such as optical parts, mechanical parts, electrical parts and so on.

Here is a common problem to be emphasized, the positioning accuracy and repeatability of the entire module is determined by the actual measurement elements and moving elements , if only to improve the encoder, grating ruler and other measuring elements of precision, for moving parts (motor, module) accuracy is not enough, Then the positioning accuracy of the entire module and repeat positioning accuracy is still not up, to give a simple example, now at 100mm, want to move to 100.1mm, grating ruler, encoder precision can be accurate to 0.1um, but the motor + module accuracy is limited, a pulse ran 1mm, Then it is not possible to run to 100.1mm at all. It is often said that my measurement accuracy is enough, why not to the precise movement ah, this is likely to be related to your sports part.

At this point, we understand the structure of the entire motion control system of PMAC, and we can begin to use it. This tutorial is mainly for the people of the PMAC software development, if the design of the entire control system designers need to further understand all aspects of knowledge.

Original, reprint please indicate from http://blog.csdn.net/wenzhou1219

2.PMAC Hardware-an example of a motion control system