Introduction

The SMOOTH function helps the robot to move smoother and reduces vibrations, by changing the motion filter ratio. The SMOOTH function is available on controller software YAS4.19-00 or later or YBS2.49-00 or later.

Overview

The SMOOTH function is ideal in a palletizing application. When the robot picks up a case and travels from the infeed station to the build station at high speeds, the robot might experience vibrations that may cause the case or product to drop, when using a vacuum gripper. Applying the SMOOTH function will alleviate some of the vibrations and make the motion path smoother and prevent the case from dropping.

Below is a video of an HC30PL YRC1000micro with Collaborative Operations disabled, moving a fully loaded case with a Schmalz Dual Vacuum gripper, at 100% Joint Move. In the first clip the robot is running without the SMOOTH function. Then in the second clip the robot runs with the SMOOTH Function. In both instances the robot is running the same job.

Video of this function:

This function is useful as well for HC robots to reduce the margin of error in the estimated external forces that can be caused by the robot's motion or vibrations.

Setup

Set parameter S2C1596 = 1 and S1C1520-1529 to the desired manipulator motion filter ratio for each axis on the robot, which the value can be set from 0 to 300. If the robot is a 6-axis robot, the manipulator motion filter can only be set to S2C1520-1525.

Figure 1: S2C1596 set to 1.

Figure 2: S1C1G1520-1525 set to 300, which is 300% the max motion filter ratio.

Then in the job, the function can be found by pressing the "INFORM LIST" key and in "OTHER" section, the SMOOTH inform command should be available.

Figure 3: Where the SMOOTH function is located.

Then in Figure 4, it explains how to setup the SMOOTH function when creating a job.

Figure 4: How to setup the SMOOTH function in a JOB.

Important Notes

• The SMOOTH function cannot be applied to jobs with multiple control groups.
• The SMOOTH instruction is executed consecutively, meaning that the last SMOOTH instruction will set the manipulator motion filter. This is described below if the job is run from the top:

SMOOTH ADDRATIO=100

SMOOTH ADDRATIO=70

SMOOTH ADDRATIO=60

MOVL V=* ← This instruction operates with a 60% manipulator motion filter.

• When the SMOOTH instruction is executed, the manipulator momentarily stops.
• When a job is stopped after executing the SMOOTH function, the manipulator motion filter that was set is disabled when the job is restarted.
• Depending on the application when running the SMOOTH function, the function will increase the inward-turning motion, meaning that it will cause the motion path to curve more. The motion will be similar as setting a Position Distance tag (reference manual 178645-1CD) in a MOVL position, which is shown below:

Figure 5: An example on how to set a PD tag and how it affects the motion path.

Figure 6: Another example of the PD tag and how the SMOOTH function will behave similarly to a PD tag.

Results

Trying to understand how the SMOOTH function affects the speed, acceleration, torque, and cycle time of the robot with different manipulator motion filter ratios, different tests were conducted on the HC30PL. Below are traces of the TCP Speed & Torque Spec from the controller oscilloscope with different motion filter ratios.

The job that was created to produce these graphs, moved the robot's S-Axis to about 90° and L & U axis about 15°-25°, basically making a simple sweep. All the point were taught using Joint Moves and the speed was set to 60% of the max speed, which was about 600mm/sec.

From reviewing the graphs, the SMOOTH function does affect the acceleration and the torque of the robot. Each manipulator motion filter ratio allows the robot to reach it's taught max speed of 600mm/sec, but at different times. Basically, each manipulator motion filter were milliseconds from each other to reach the max speed.

With the torque traces, the SMOOTH function does affect the torque, causing the S-Axis to experience a smaller torque when a higher manipulator motion filter ratio was used.

From the TCP Speed curves, the SMOOTH function does affect the cycle time. When using a smaller manipulator motion filter ratio, the TCP reached its max speed sooner.

Figure 7: Overall TCP Speed when the job ran for 5 seconds.

Figure 8: TCP Speed in the first 1.1 seconds of the job running.

Figure 9: Torque values of the S-Axis when a job ran.

Figure 10: Torque values of the S-Axis in the first 1.5 seconds.

Conclusion

When setting up the SMOOTH Functions, start by setting the manipulator motion filter ratio to the max, which is 300%. Then test to see if using a lower motion filter ratio will still improve the overall motion of the application. Using the SMOOTH function will affect the cycle time, but it will be a small change that it might not affect the overall cycle time, depending on the application. For additional information on the SMOOTH function, read section 6.27 Manipulator Motion Filter Setting Function on the YRC1000 General Operator's Manual (178645-1CD.pdf), section 6.26 Manipulator Motion Filter Setting Function on the YRC1000micro General Operator's Manual (181257-1CD), or 14.1 Manipulator Motion Filter Setting Function on the YRC1000/YRC1000micro Collaborative Operation Instructions (181437-1CD).