Rookie study four Axis Controller 6: Tool RADIUS compensation algorithm

Why should I have tool compensation?

Imagine that if our tool can be ideal to a radius of infinity, but we do not need to consider the radius of compensation, but in fact, we use the edge of the tool to carve objects, such as:

In simple terms, it seems that the direct parallel to the contour of the movement can be, in fact, a single line of the carving is parallel, but straight and straight lines, lines and arcs, arcs and arcs are different, and! The tool compensation of straight line and straight line is also divided into three kinds of case analysis. In theory, there are two ways to compensate.

Wait, also divided into three steps, the first step is to establish compensation, the second step to compensate, the third step to cancel compensation.

The two methods were:

1, B Tool RADIUS compensation

2, c tool RADIUS compensation

In accordance with past practice, it is clear that the first method is simple and crude and effective. The second is a bit more complicated, but more precise.

A single line and arc of the tool offset, very simple to calculate the line and arc of the tool compensation formula is as follows:

The formula is very simple, in fact, and interpolation algorithm combined together, it is more complex, the typical method has R2 method, polar coordinate method and vector discriminant method, if you want to know the principle of specific methods, you can refer to the following links:

http://jpkc.nwpu.edu.cn/jpkc2005/34/dianzikejian/

It is important to note that in the case of B-tool radius compensation, such as line and arc connections, an excessive algorithm is required, or the tool is discontinuous and produces errors. Over time we use to compensate for a tangent arc, and in the B-tool compensation, there is a sharp angle of the problem to be dealt with, so in the numerical control system, specifically added a G39 compensation instructions.

C Tool Compensation Method:

This compensation method used to 4 cache, in order to be called Bs,cs,as,os, in short, the interpolation of the line segment instruction first into the BS, the first, continue to pass to CS, continue to load the second instruction to BS, this time to judge what the BS and CS need to do the tool compensation, this is the key to the problem, After the processing is completed, the compensation is fed into the as,as for operation and sent to the OS for pulse output.

When the instruction passes in the next buffer, that is, after the last buffer completes a pass, continue to remove an instruction.

There are three types of situations where compensation is required:

Straight and Straight lines

Lines and arcs

Arcs and arcs

In line and straight line of the transfer, according to the angle of the two straight lines, can be divided into the following five kinds of situations.

Overall, it is shortened type, insertion type and elongation type.

The other two cases are similar to these five cases.

The calculation flow for arcs is as follows:

Summing up, the algorithm of tool radius compensation is an algorithm of bridge between ideal and reality, it is not difficult to understand, but it is not an easy thing to judge, calculate and execute every possibility.

Problem: MCX314 and PCL6045 This special chip, it should use the tool compensation algorithm, such as interpolation algorithm with the comparison of the original DDA algorithm, and tool compensation is the C tool compensation method.

Rookie study four Axis Controller 6: Tool RADIUS compensation algorithm