Vacuum Large Gripper Kit (VLG)

This page provides a detailed overview about the Vacuum Large Gripper Kit (VLG). 

Contents

• Contents
• Overview
• Hardware
• Software
• Applications
• User Guide
• Technical Specifications
• Suction Cup Information
• Kit Components
• Technical Drawings

Overview

Assembling, configuring, and troubleshooting a ClickSmart gripper is easy once a few basic concepts are understood. The picture-based User Guides are meant as a quick easy reference to assemble the hardware. This document is meant to be a supplement to that and to explain the entire concept of how and why things work the way they do. There are two aspects of setting up a ClickSmart gripper; hardware and software, which are interrelated and play an important role in the operation of the gripper. Assembling, configuring, and troubleshooting a ClickSmart gripper is easy once a few basic concepts are understood. The picture-based User Guides are meant as a quick easy reference to assemble the hardware. This document is meant to be a supplement to that and to explain the entire concept of how and why things work the way they do. There are two aspects of setting up a ClickSmart gripper; hardware and software, which are interrelated and play an important role in the operation of the gripper.

Hardware

Air Valves

ClickSmart grippers use a 5/2-way (5 ports and 2 positions), single solenoid, pneumatic valve. The same valves are used for the parallel and vacuum grippers. The large grippers have one, and the small grippers have two each. This valve has 1 port for the supply air, 2 output ports, and 2 exhaust ports. There is a pneumatic fitting on the supply and on one of the output ports. The other output port is plugged, and the exhaust ports do not have any fittings. The valve has two different states. The first state is with one of the output ports open (supplying positive air pressure) and with one closed (no air pressure). The second state is the opposite, with the first port closed and the second one open. All the valve does is switch between these two states. Since one of the output ports on the valve is plugged, it acts as a simple on/off valve. In one state the valve allows air to pass through, and in the other state it does not.

One of the two states is the “normal” state, which means the state of the valve when there is no power to it. The port that is open in the normal state is referred to as “normally open” and the one that is closed in the normal state is “normally closed”. This is important because if the arm loses power, including during an emergency stop, the valve will revert to the normal state. You may want to configure the gripper such that it is in the gripping position in the normal state so that if it is holding a part when it loses power, it will not drop it. In addition, knowing how the air is plumbed from the valve is necessary when configuring the signals.

Note: One of the ports is labelled with a "P". This is the normally open output. Do not let it confuse you since "P" sometimes stands for pressurized, meaning the input.

If you use the normally open port (the one that comes unplugged from the factory), the vacuum will be on when the robot is powered down. As previously mentioned, the benefit of this is that it will not drop a part if the arm loses power. However, this also means when you power down the robot, you will want to turn off the supply air to it so it is not constantly running. If you don’t have a separate valve to turn off the supply air, or this is not how you want the gripper to operate, swap the position of the plug and the pneumatic fitting so that the vacuum generator is connected to the normally closed port.

Vacuum Generator (VLG and VSG only)

The VLG and VSG use the vacuum generator show in the picture below. The VFG (foam gripper) has a vacuum generator integrated into the gripper body. The vacuum generator has 3 ports: an input, a vacuum, and an exhaust. The output of the valve is connected to the input of the vacuum generator with an air hose. The vacuum port is connected to the suction cups, with the vacuum sensor in the middle. The exhaust port will have a silencer attached.

Vacuum Sensor

The vacuum sensor measures the amount of vacuum and provides an analog input to the robot. This is used to determine whether or not the part is being gripped. For the VLG and VSG, it needs to be inserted between the vacuum generator and the suction cups using either the “Y” or “T” fitting.

Logical Diagram of Air and Wiring – VLG and VSG

The image above shows the Vacuum Large Gripper (VLG). The Vacuum Small Gripper (VSG) is the same, except doubled using the other port on the ClickSmart Plate.

Logical Diagram of Air and Wiring – VFG 

Software

After connecting the ClickSmart to the robot, you will need to open the tooling gallery to configure the gripper. Enter a name, its mass, tool center point offsets, and estimated center of mass. Scroll down and select “Vacuum” as the tool type. After saving, the gripper should work, but maybe not as expected, especially when using train-by-demonstration. This is because the signals need to be configured to match the hardware configuration and expected behavior.

Let’s assume that you want the “normal” state of the vacuum to be on so the robot doesn’t drop a part when it loses power.

Because configuring a task in Intera Studio is so flexible, you are free to configure the signals any way you like, then use the correct combination of outputs and inputs to achieve the desired behavior. However, the templates and train-by-demonstration on the robot make the following assumptions.

• Outputs
  • Sensor Power: On
  • Vacuum On:
    • True: vacuum on to grasp the part
    • False: vacuum off to release the part
• Inputs
  • Vacuum Sensor / Vacuum Threshold:
    • The value of the Vacuum Sensor is less than the Vacuum Threshold when not grasping a part
    • The value of the Vacuum Sensor is greater than the Vacuum Threshold when grasping a part

When both open and closed are false, the fingers are neither all the way open, nor all the way closed. This must mean the gripper is grasping a part.

Note that there are 2 sets of the same signals, designated as A and B. This refers to the connector on the ClickSmart plate to which the cable is connected. The large gripper uses only one port while the small gripper uses both both ports since there are 2 grippers.

Output Signals

Power - This controls whether the 24V to the vacuum sensor is on or off. This should be configured so it is on all the time, which the default values should do.

• Port: A_out1 (or B_out1)
• Default: true
• Inverted: off

Vacuum On - This is the signal to the pneumatic valve that tells it which state to be in. No signal means it is in the “normal” state. If you connected the normally open port on the valve to the vacuum generator, the vacuum will be on when this signal is low. The reverse is true; when the signal is high, the vacuum will be off. Setting the Vacuum On signal in software to ‘false’ typically means the electrical signal is low, and setting grip to ‘true’ typically means the electrical signal is high. So, this results in ‘false’ = grip the part, and ‘true’ = release the part. This is a problem because the train-by-demonstration functionality assumes the opposite. To fix this, we enable “invert signal” to flip this logic (this is the default position). This will make it so that setting Vacuum On to ‘true’ sets the signal low (de-energizing the solenoid, returning the valve to the normal state) and turns on the vacuum, and setting Vacuum On to ‘false’ sets the signal high (energizing the solenoid, switching the valve) and turns off the vacuum.

• Port: A_out2 (or B_out2).
• Default: This will be the state of the gripper when a task is reset. Typically this should be false so the vacuum is off. Keep in mind that if a part is being gripped when the task is reset, it will drop the part.
• Invert signal: ‘On’ if the hardware is connected as described above. Test to make sure that that true = grip and false = release. If not, toggle this setting.

Input Signals

Vacuum Sensor - This is the analog signal which represents the vacuum level used to determine if a part is being gripped or not. Do not change any of the values for this signal unless you need to swap between the A and B ports.

Vacuum Threshold - Within this signal is a parameter also called ‘vacuum threshold’ which has a default value of 50. This means if the vacuum sensor value goes above 50, the Train-by-Demonstration and template pick logic will assume a part is grasped. If it is below, it will assume it is not grasping a part. To start, leave the default value of 50. This may have to be lowered if there are many suction cups and/or the part is porous.

After saving the configuration of the signals, open up Shared Data (from the toolbar in the top right of the screen) to make sure the signals are working correctly.

• Make sure the supply air to the valve is connected and turned on.
• Find the signals for the gripper by navigating to “Current Tasks Shared Data -> Signals”.
• Find the outputs under “Signal: Out -> Tool name -> Subtool name”.
• Find the “Power” signal and make sure it is True. If it is false, check the configuration and make sure it is set to a default value of True.
• Find the other output signal called “Vacuum On”. Set it to true and make sure the vacuum is on. Set it to false and make sure the vacuum is off. If it works the opposite way, check the configuration and toggle the ‘Invert Signal’ setting. If it doesn’t turn on, check to make sure the supply air is on.
• Make the ClickSmart gripper the active tool center point in the task, then press and hold the white oblong button on the cuff of the robot. This should toggle the vacuum on and off with each press and hold.
• Find the inputs under “Signal: In -> Tool name -> Subtool name”.
• When the gripper is not holding a part, the Vacuum Sensor should be around 20. If it is 0, then go back and check that the input ‘Power’ is on and is not inverted. Also check to make sure the correct port (A or B) is being used.
• Toggle the vacuum on and place the part in the gripper to see what the value of Vacuum Sensor is. If it is less than 50, go back to the configuration of the Vacuum Threshold signal and adjust it. The value of the Vacuum Threshold signal should be somewhere between 20 and the value when it is holding the part.

Applications

User Guide

To download the user guide, please click here.

Technical Specifications

Gripper Component Weight Specifications

Suction Cup Information

Suction Cup for VLG (P/N: 99-00000601-00)

Suction Cup for VLG (P/N: 99-00000602-00)

Kit Components

Technical Drawings

ClickSmart Vacuum Gripper Cable