Strange behaviour of axis 4 and missing 90 degrees of axis 5
Hey,
I am struggling with a few of my problems:
The robot is AR3 modified to AR4 (teensy 4.1, teensy4.1 program with cui encoders, plus endstops I modified for inductive sensors).
The encoders in these videos are disabled.
In the program I changed the lines through the inductive sensors (to align the axes.)::
//degrees from limit switch to offset calibration
float J1calBaseOff = -1;
float J2calBaseOff = -13.1;
float J3calBaseOff = 10.4;
float J4calBaseOff = -1.5;
float J5calBaseOff = 87;
float J6calBaseOff = 17;
float TRcalBaseOff = 0;My problems are the strange behaviour of axis 4 when driving axis X. Is this rotation normal?
The second problem is that the gripper is not kept parallel to the base. Additionally, axis 5 after axis calibration has an angle of 0 degrees. When I go to 90 degrees (as in the video) it has about 92~3 degrees. Is the value of steps per degreee incorrect?
And how can it be calculated? The controller's microstep settings are as in the manual.
Third problem is this humming sound of axis 4 stepper motor. After connecting it to another controller (TMC2208, TMC2209, DRV8825) it does not make this sound. (But this is the smallest problem).
Chris Annin
I believe the rotation of axis 4 you are seeing is wrist singularity and that is normal for a 6 axis robot. It happens when axis 4 and 6 are aligned and the robot tcp is moving in a direction where axis 4 or 6 need to rotate a significant amount to resolve the wrist orientation. Here is a video that illustrates wrist singularity.