Hi Michael,
Max Error = clamp the error at this value. So for example with a Max Error of 100 counts if the error somehow becomes a large value such as 10,000 counts the servo will respond as if the error was only 100 counts. This can be useful in abnormal cases for example if the axis is manually forced far off position and released. Rather than reacting violently and saturating the amplifier in a way that would likely grossly overshoot the target, the servo can be made to respond more reasonably until the error reduces to a small value.
Max Following Error = disables the axis if the error (difference between commanded and actual positions) ever exceeds this value.
Note that when a small Max Following Error is used the Max Error parameter is unlikely to ever come into play as the axis will be disabled beforehand.
See here for exactly how Max Error, Max Integrator, and Max Output are implemented:
Regards
TK
| Group: DynoMotion |
Message: 4632 |
From: Tom Kerekes |
Date: 4/23/2012 |
| Subject: Re: Weird axis counting |
Hi Michael,
It is important to understand the there are two different types of motion they are referred to as independent and coordinated. Independent motions are when each axis moves on an independent trajectory (even though multiple axes may be moving at the same time). Rapid moves (G0), Jogging, Step Response Moves, and homing moves (C program moves) are independent motions that use the settings in KFLOP (set by the Init.c) file. These are 3rd order motions that are smooth in the sense that Jerk is limited so that Acceleration (=torque=force=current) is applied gradually rather than instantly applied creating a large shock. Coordinated motions are used for GCode paths defined with G1,G2, G3 commands. The trajectory planner is only capable of
planning 2nd order motion which involves limiting Acceleration and Velocity (Jerk is infinite). The settings in the Trajectory Planner Screen are for the Coordinated motion. To make things more confusing KFLOP doesn't know about the system resolution so its parameters are in counts or steps. The Trajectory Planner knows about the system resolution so its parameters are in inches. The max Acceleration and max Velocity settings for each type of motion are not necessarily the same. It is common to be able to do higher acceleration and velocity when Jerk is limited. To test infinite Jerk type of motion using KMotion's Step Response Screen temporarily set the Jerk to infinity (1000X of the Acceleration).
Regards
TK
| Group: DynoMotion |
Message: 4634 |
From: Michael Rosenfield |
Date: 4/23/2012 |
| Subject: Re: Weird axis counting |
Yup, you were 100% correct! I had good settings for short moves KFlop, but not good settings for KMotionCNC and TP. Plus, the axis moves so slowly that the error was building up over long moves. I couldn't see this in the Step/Move screen because it move took about 4.5 seconds. All fixed now! Many Thanks! Michael | | | |
