Notes for Safe Operation

Error detecting functions

When force is limited using the compliance function, the robot may move toward the force limiting direction due to external force. The robot may also move due to the component force in a force limiting direction of an external force applied in a direction other than the force limiting direction. The following functions have been added to detect any abnormality/error for the safety in adjusting the robot.

1. Force control, arm end deviation error (8320152E)
   This error occurs when the position deviation of the robot tool tip exceeds the allowed value. The initial values for allowed deviation is 100 (mm) along and 10 (deg) about the X, Y, and Z axes. "ForceParam" command can be used to change the allowable deviation.

   Setting a large value for allowable deviation may prevent errors from being detected. Therefore, do not set excessive limits.

2. Force control, command value error (8320152F)
   This error occurs when excessive force is detected at the robot tool tip. It occurs when the robot performs a push motion towards the direction in which a high force limiting rate is set. If this error occurs, make sure that the force limiting direction and force limiting parameters are set properly.

3. Force control, exceeding speed limit (83201530)
   High speed motion cannot be performed while compliance function is enabled. This error occurs if a motion command is executed when the product of the external speed and internal speed exceeds 50%. If this error occurs, reduce the internal speed setting.

4. Cannot restart motion while force control enabled. (83201533)
   This error occurs if you start the continue motion or restart in the resuming pass mode while compliance function is enabled.

For safety during adjustments

To secure the safety of personnel and machinery during adjustment tasks, do not set any excessive values for the allowable position deviation and allowable axis deviation. Also, before you perform any adjustment, use the "ForceParam" command to set values that are smaller than the initial values (10 (mm) along and 5 (degrees) about the X, Y and Z axes) for allowable deviations in all directions except the force limiting direction.

Adjusting parameters for the compliance function

Adjust the limiting force used while compliance function is enabled to a value based on the force limiting rate. Note that the relationship between the force limiting value and force limiting rate will vary according to the posture and direction of the robot. Adjust the parameters for each force limiting posture and direction.
The robot's motion will be affected by and follow the direction of force when the joint torque due to external force becomes larger than the static friction of the joint. On the other hand, if the static friction is larger than the joint torque due to external force, the robot stays in equilibrium.
The robot may move toward the force limiting direction (direction specified by the command value) if the equilibrium between the friction and limiting force changes as the result of friction change due to posture alteration during robot operation while compliance function is enabled. Pay attention to the robot's motion toward the force limiting direction when operating the robot while compliance function is enabled.

Position teaching

Use the function for setting position into variables to teach the position of the robot. The position set into the variable is the current command position of the robot. When you directly push the robot to move and set positions (direct teaching) with the force limiting function, there will be some misalignment between the teaching position and actual position. This is because the robot's command position differs from the actual position. Follow the procedure below to teach positions using the force limiting function.

1. Decide an I type variable to use as the teaching number. "I0" is used in this example.
2. Create the following program.

• To use P type variables for teaching:
  Specifiy "DirectTeach.pcs" as the file name for this example.

Sub Main
    P(I0) = Destpos
End Sub

• To use J type variables for teaching:

Sub Main
    J(I0) = Destjnt
End Sub

3. Assign "I0" as the position teaching number, move the robot to the teaching position, and then execute "DirectTeach."

Setting tool and work coordinates

You cannot change tool coordinates and work coordinates when the Compliance Function with Force Sensor is performed.

Robot motion accuracy while compliance function enabled

When a motion command is executed while compliance function is enabled, accuracy of the motion path of the robot decreases. The position in the force limiting direction may present a large deviation. If accurate motion is required, disable the compliance function.
The stop accuracy of the robot decreases while compliance function is enabled.
If the encoder value check motion (refer to "Encoder value check motion") is performed while compliance function is enabled, the robot may stop for a longer period, or the error "8320403* Encoder value check motion timeout" may occur. If accurate stop motion is required, disable the compliance function.