Troubleshooting

The Force Sensor is not recognized

Refer to the following section and check the wiring.
Hardware Connection Example

Pay particular attention to the following items.

  • Force Sensor Cable
  • Force Sensor M/I Cable
    Check the hardware connections and then refer to the following section and enable the Force Sensor.
    Software Checking the Connection

The output value of the Force Sensor differs from the actual force direction

Refer to the following section and check the coordinate system.
Installation Robot local

All of the following items impact the Force coordinate system.

  • Settings of the Base, Local, and Tool coordinates
  • Setting of FlangeOffset
  • Setting of the force coordinate object (FCS#)

The output value of the Force Sensor differs from the actual force

The output of the force and torque when the Force Sensor is reset is set as "0" for the Force Sensor. Therefore, if an external force is being applied when the Force Sensor is reset, the Force Sensor detects a force even if no force is actually applied after the external force is removed. To avoid this, reset the Force Sensor when no external force is being applied. Also, weight of the Force Sensor is applied depending of the robot posture since the detection position is located at the center of the Force Sensor structure.

Furthermore, if the posture of the Force Sensor changes from that when the Force Sensor is reset, the output value of the Force Sensor also changes due to the effect of gravity. If the posture of the Force Sensor does not change in the operation using the force functions (force control, force trigger, and force monitor), reset the Force Sensor immediately before using the force functions.

If the posture changes during executing of the force functions, the effect of gravity can be reduced by using gravity compensation. For the details, refer to the following section.
Software Gravity Compensation

The output value of the Force Sensor changes over time.

Epson Force Sensor has drift characteristics. If the change is within the range of the time drift described in the following section, it is normal.
Hardware Specification
To avoid the effect of the time drift, reset the Force Sensor immediately before using the force functions. Use the force functions within 10 minutes after resetting the Force Sensor.

Abnormality occurs on the Force Sensor

If an error regarding the Force Sensor occurs, refer to the following manual and take measures against the error.
"Epson RC+ 8.0 SPEL+ Language Reference" - SPEL+ Error Messages

If the Force Sensor is used for a long time without being reset, an error accumulates due to the drift. This may result in an element error of the Force Sensor. If the error occurs, executes the Reboot property of the force sensor object.

Furthermore, accuracy abnormality of the Force Sensor may occur when the Force Sensor is hit against the peripherals or when an error occurs on the Force Sensor. In this case, check that the Force Sensor is working properly. For the details, refer to the following section.
Software Checking the Accuracy of the Force Sensor

You cannot perform the intended motion by the force guide object(s)

For the motions by the force guide object(s), if you cannot perform the intended motions (e.g. larger force than expected is applied), refer to the following section and adjust properties.

An error 5546 occurs

An error 5546 may occur when executing the Reset property while vibrations from an external device are applied to the Force Sensor. If the vibration is intermittent, this error can be avoided by specifying "FG_RESET_WAIT_VIBRATION" in the Reset property.
In addition to receiving an error 5546, environments where a continuous vibration is applied may also adversely impact the accuracy of the force control function. Place a rubber sheet on the legs of the system to eliminate any external vibrations the robot may be subjected to.

The robot moves in the opposite direction to the intended direction

Epson's Force Sensor is a sensor that senses the application of force. Note that the direction between the robot motion direction and the pressing force/detection force to be set are always opposite.
For example, if you specify Press+ (pressing to the positive direction) in Fx_ControlMode of the Press object, you need to set a negative value to Fx_PressForce. The force recorded as the motion result will also be a negative value.
This also applies for the force control function using a ForceControl object. To move and press the robot in the +Fx direction, you will need to set a negative value to Fx_TargetForce.

Contact takes too long

The robot's speed of motion needs to be reduced to keep within overshoot limits when making contact. This may result in worse cycle times.
If this happens, set the approach point for commencing the contact motion close to the contact point to reduce contact times. However, it is important to set a point that avoids collisions while traveling to the approach point, considering variations in the workpieces used.
When executing the contact motion using Till FT, this issue can be improved by setting FG_SOFT_STOP in TillStopMode.

The robot does not reach the destination

When executing Move or another operation command with the force control function enabled for a specific direction only, the axis may not be able to reach its destination if the force control function is disabled for the axis. This occurs when the LimitSpeedSRJ property and the LimitAccelSRJ property in the force control object restricts the speed and acceleration required for movement.

You can check speed and acceleration restrictions with the MotionLimited status.
If restrictions apply, increase the LimitSpeedSRJ property and the LimitAccelSRJ property to ensure unrestricted movement, and allow the axis to reach its destination. Note, however, that the force control function increases the speed and acceleration in proportion with the force applied. Make sure to adjust these settings within the tolerable range.
If this cannot be adjusted using the LimitSpeedSRJ property and the LimitAccelSRJ property, reduce the SpeedS and AccelS properties specified for Move or another operation command, to ensure unrestricted movement, and allow the axis to reach its destination.

Low power restrictions will automatically limit the LimitSpeedSRJ property and the LimitAccelSRJ property when in low power mode. If increasing the LimitSpeedSRJ property and the LimitAccelSRJ property settings will have no effect, check whether the system is in low power mode.

The robot bounces excessively when pressing

If the LimitSpeedSRJ property and the LimitAccelSRJ property values are small, the speed and acceleration required will be limited, and the robot may bounce excessively when moving in reaction to the force applied.
If this happens, increase the LimitSpeedSRJ property and the LimitAccelSRJ property settings.
Low power restrictions will automatically limit the LimitSpeedSRJ property and the LimitAccelSRJ property when in low power mode. If increasing the LimitSpeedSRJ property and the LimitAccelSRJ property settings will have no effect, check whether the system is in low power mode.

Certain properties do not appear

Properties not supported by the version of the controller firmware in use will not appear. Try updating your controller firmware.

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