7th Axis Gravity Settings
Gravity setting when accelerating/decelerating a 7th axis
Example is valid for:
CB2 Software version: All
CB3 Software version: All
e-Series Software version: All
Note that older or newer software versions may behave differently.
When a robot is mounted on a slide(7th axis) that is moving the robot from station to station, external forces are applied to the robot that easily can cause the robots own mass to cause a protective stop or perhaps cause a wrong mounting fault.
These external forces can be represented as additional gravitational forces using the command:
set_gravity(gx,gy,gz)
With no external forces applied to a robot mounted in a base down orientation, the command that is issued internally as part of the installation file is:
set_gravity(0.0,0.0,9.82) because 1g of gravity = 9.82 m/s^2.
When accelerating the same robot in the x direction with an acceleration rate of ax = 0.5 g or 4.91 m/s^2 the command looks like this:
set_gravity(4.91,0.0,9.82)
When moving at a constant velocity in the x direction back to the original setting:
set_gravity(0.0,0.0,9.82)
When decelerating while moving in the same direction:
set_gravity(-4.91,0.0,9.82)
It is good practice to keep the robot joints stationary while the linear stage is in motion, especially when accelerating and decelerating.