4. Control

4.1. Overview

The Robotiq Hand-E Gripper is controlled directly via Modbus RTU using a RS485 signal. It can also be controlled via an optional Robotiq Universal Controller using an industrial protocol (refer to the instruction manual of the Robotiq Universal controller). The programming of the Gripper can be done with the Teach Pendant of the robot or by offline programming. The communication method used to control the Hand-E Gripper does not change the control logic or register setups described in the following subsections.

Since the Robotiq Hand-E Gripper has its own embedded controller, high-level commands, such as "Go to requested position" are used to control it.

Control using registers

The Gripper has an internal memory that is shared with the robot controller. One part of the memory is for the robot output; gripper functionalities. The other part of the memory is for the robot input; gripper status. Two types of actions can then be performed by the robot controller :

1. Write in the robot output registers to activate functionalities;
2. Read in the robot input registers to get the status of the Gripper.

The Gripper Register Mapping section will map the different registers used to control the Gripper or to read its status while theRobot Output Registers & Functionalities section will detail the output (write) register functions, and the Robot Input Registers & Status section will detail the input (read) register status. The figure below is a representation of the memory and the control logic of the Gripper.

Fig. 4-1: Hand-E control logic overview

Control using Universal Robots packages

Robotiq provide Universal Robots packages to be used with URCaps (require controller CB3 or higher)

Please refer to the Control over Universal Robots with URCaps section for instructions on how to use the Gripper URCap; this method will provide you with a Gripper Toolbar to test and a Gripper node to program via the URCaps tab.

Please refer to the Control over Universal Robots without URCaps section on how to use without URcaps, this method will provide you with a similar Gripper Toolbar but the robot program will be built using subprograms and scripts.

4.2. Gripper Register Mapping

Register mapping

Table 4-1: Registers of the Hand-E Gripper.

4.3. Robot Output Registers & Functionalities

Register: ACTION REQUEST

Address: Byte 0

rACT

First action to be made prior to any other actions; the rACT bit will activate the Gripper. Clear the rACT bit to reset the Gripper and clear any fault status.

• 0x0 - Deactivate Gripper.
• 0x1 - Activate Gripper (must stay on after activation routine is completed).

rGTO

The "Go To" action moves the Gripper fingers to the requested position using the configuration defined by the other registers, rGTO will engage motion while bytes 3, 4 and 5 will determine aimed position, force and speed. The only motions performed without the rGTO bit are activation and automatic release routines.

• 0x0 - Stop.
• 0x1 - Go to requested position.

rATR

Automatic Release routine action slowly opens the Gripper fingers until all motion axes reach their mechanical limits. After all motions are completed, the Gripper sends a fault signal and needs to be reinitialized before any other motion is performed. The rATR bit overrides all other commands excluding the activation bit (rACT).

• 0x0 - Normal.
• 0x1 - Emergency auto-release.

rARD

Auto-release direction. When auto-releasing, rARD commands the direction of the movement. The rARD bit should be set prior to or at the same time as the rATR bit, as the motion direction is set when the auto-release is initiated.

• 0x0 - Closing auto-release
• 0x1 - Opening auto-release

Register: GRIPPER OPTIONS

Address: Byte 1

Register: GRIPPER OPTIONS 2

Address: Byte 2

Register: POSITION REQUEST

Address: Byte 3

This register is used to set the target position for the Gripper's fingers. The positions 0x00 and 0xFF correspond respectively to the fully opened and fully closed mechanical stops. For detailed finger trajectory, please refer to the Specifications section.

• 0x00 - Open position, with 50 mm opening
• 0xFF - Closed
• Opening / count: ≈0.2 mm for 50 mm stroke

Register: SPEED

Address: Byte 4

This register is used to set the Gripper closing or opening speed in real time, however, setting a speed will not initiate a motion.

• 0x00 - Minimum speed
• 0xFF - Maximum speed
•  

Register: FORCE

Address: Byte 5

The force setting defines the final gripping force for the Gripper. The force will fix the maximum current sent to the motor . If the current limit is exceeded, the fingers stop and trigger an object detection notification. Please refer to the Picking Features section for details on force control.

• 0x00 - Minimum force
• 0xFF - Maximum force

4.4. Robot Input Registers & Status

Register: GRIPPER STATUS

Address: Byte 0

gACT

Activation status, echo of the rACT bit (activation bit).

• 0x0 - Gripper reset.
• 0x1 - Gripper activation.

gGTO

Action status, echo of the rGTO bit (go to bit).

• 0x0 - Stopped (or performing activation / automatic release).
• 0x1 - Go to Position Request.

gSTA

Gripper status, returns the current status and motion of the Gripper fingers.

• 0x00 - Gripper is in reset (or automatic release) state. See Fault Status if Gripper is activated.
• 0x01 - Activation in progress.
• 0x02 - Not used.
• 0x03 - Activation is completed.

gOBJ

Object detection status, is a built-in feature that provides information on possible object pick-up. Ignore if gGTO == 0.

• 0x00 - Fingers are in motion towards requested position. No object detected.
• 0x01 - Fingers have stopped due to a contact while opening before requested position. Object detected opening.
• 0x02 - Fingers have stopped due to a contact while closing before requested position. Object detected closing.
• 0x03 - Fingers are at requested position. No object detected or object has been loss / dropped.

Register: RESERVED

Address: Byte 1

Register: FAULT STATUS

Address: Byte 2

gFLT

Fault status returns general error messages that are useful for troubleshooting. Fault LED (red) is present on the Gripper chassis, LED can be blue, red or both and be solid or blinking.

• 0x00 - No fault (solid blue LED)
• Priority faults (solid blue LED)
  • 0x05 - Action delayed; the activation (re-activation) must be completed prior to perform the action.
  • 0x07 - The activation bit must be set prior to performing the action.

Minor faults (solid red LED)

• 0x08 - Maximum operating temperature exceeded (≥ 85 °C internally); let cool down (below 80 °C).
• 0x09 - No communication during at least 1 second.

Major faults (LED blinking red/blue) - Reset is required (rising edge on activation bit (rACT) needed).

• 0x0A - Under minimum operating voltage.
• 0x0B - Automatic release in progress.
• 0x0C - Internal fault, contact support@robotiq.com
• 0x0D - Activation fault, verify that no interference or other error occurred.
• 0x0E - Overcurrent triggered.
• 0x0F - Automatic release completed.

kFLT

please refer to your optional controller manual (input registers and status).

Register: POSITION REQUEST ECHO

Address: Byte 3

gPR

Echo of the requested position for the Gripper, value between 0x00 and 0xFF.

• 0x00 - Full opening.
• 0xFF - Full closing.

Register: POSITION

Address: Byte 4

gPO

Actual position of the Gripper obtained via the encoders, value between 0x00 and 0xFF.

• 0x00 - Fully opened.
• 0xFF - Fully closed.

Register: CURRENT

Adress: Byte 5

gCU

The current is read instantaneously from the motor drive, value between 0x00 and 0xFF, approximate current equivalent is 10 * value read in mA.

4.5. Picking Features

As stated in previous sections, object picking is done via a simple "Go To" command, rGTO bit calls for movement, while rPR byte is the aimed position, rSP and rFR will be the desired speed and force settings respectively. This section describes key features in object picking applications:

• Force control
• Re-grasp
• Object detection
• Object contact loss

4.5.1. Force control

The gripping force is controlled via the rFR byte (please refer to the Robot Output Registers & Functionalities section).The Gripper behavior will change according to the rFR force requested.

• rFR = 0 : Very fragile objects or deformable objects mode
  • Lowest force
  • Re-grasp feature is off
• 1 rFR 255 : Solid & firm objects
  • High torque mode
  • Re-grasp feature is on

Measured grip force for steel of specific hardness (Vickers)

Coming soon

Measured grip force for silicone of specific hardness (Durometer)

Coming soon

4.5.2. Re-Grasp

Re-grasp feature is a built-in feature meant to prevent object lost due to slipping or inaccurate initial grip. The Re-grasp feature will allow the Gripper to initiate a movement when an object is slipping or dropped. When Re-grasping, the Gripper will attempt to close until it reaches the position request (rPR).

• This feature is automatically set according to the force request rFR.

• Re-grasp will keep the position setting:
  • Finger motion will stop when rPR position is reached, even if there is no object.
• Force and speed settings are not used, Re-grasp force and speed will automatically adjust to keep the object from being lost / dropped.

4.5.3. Object detection

When the Gripper grabs an object, the gOBJ status will allow you to know if contact with the object was successful. This is a built-in feature for adaptive grippers meant to be used by the robot controller (or PLC) commanding the overall application. The Object detection feature will change the gOBJ status and can be used inside your robot program.

As stated in the previous section:

gOBJ: Only valid if gGTO = 1.

• 0x00 - Fingers are in motion towards requested position. No object detected.
• 0x01 - Fingers have stopped due to a contact while opening before requested position. Object detected.
• 0x02 - Fingers have stopped due to a contact while closing before requested position. Object detected.
• 0x03 - Fingers are at requested position. No object detected or object has been lost / dropped.

Example of contact detected with an object:

1. Set position, speed and force at maximum (full closing):
   1. rPR == 0xFF, rSP == 0xFF, rFR ==0xFF,
2. Set ''go to requested'' will initiate movement :
   1. rGTO == 0x01
3. Then object detection status will be "in motion"
   1. gOBJ == 0x00
4. Until an object is picked, object detection status will then be "stopped due to contact while closing"
   1. gOBJ == 0x02
5. The user can now assume it is holding the payload, and proceed to the next step.

Example of contact lost with an object:

1. From the previous example, after an object is picked
   1. gOBJ == 0x02
2. If the gOBJ status displays 0x03 after it was 0x02, user can assume contact with the object has been lost.

4.5.4. Brake engagement

The Hand-E Gripper is equipped with a brake that engages at the end of each and every Gripper move, and thus disengages between each of these moves.

For instance, when fully closing on an object, the Gripper makes contact with the surface of the object and activates the brake before sending the object detection signal to the robot.

4.6. Control Logic Example

Fig. 4-2: Example of Gripper control logic with corresponding registers.

4.7. Modbus RTU Communication

The Gripper can be controlled by Modbus RTU directly with RS485 or over USB using the ACC-ADT-USB-RS485. This section is intended to provide guidelines for setting up a Modbus master that will adequately communicate with the Gripper.

For a general introduction to Modbus RTU and for details regarding the CRC algorithm, the reader is invited to read the Modbus over serial line specification and implementation guide available at: http://www.modbus.org/docs/Modbus_over_serial_line_V1_02.pdf.

For debugging purposes, the reader is also invited to download one of many free Modbus scanners such as the CAS Modbus Scanner from Chipkin Automation Systems available at: http://www.store.chipkin.com/products/tools/cas-modbus-scanner.

4.7.1. Connection Setup

The following table describes the connection requirements for controlling the Gripper using the Modbus RTU protocol.

¹ Various converters are available in the Spare Parts, Kits and Accessories section.

² These parameters can be adjusted using the Robotiq User Interface.

Each register (word - 16 bits) of the Modbus RTU protocol is composed of 2 bytes (8 bits) from the Gripper. The first Gripper output Modbus register(0x07D0) is composed from the first 2 Robotiq Gripper bytes (byte 0 and byte 1).

4.7.2. Read holding registers (FC03)

Function code 03 (FC03) is used for reading the status of the Gripper (robot input). Examples of such data are Gripper status, object status, finger position, etc.

Example of an FC03 read function:

This message asks for register 0x07D0 (2000) and register 0x07D1 (2001) which contains Gripper Status, Object Detection, Fault Status and Position Request Echo.

Request is: 09 03 07 D0 00 02 C5 CE

Response is: 09 03 04 E0 00 00 00 44 33

4.7.3. Read input registers (FC04)

Function code 04 (FC04) is used for requesting the status of the Gripper's analog input register. Examples of such data are Gripper status, object status, finger position, etc.

Example of an FC04 read function:

This message asks for register 0x07D0 (2000) and register 0x07D1 (2001) which contains Gripper Status, Object Detection, Fault Status and Position Request Echo.

Request is: 09 04 07 D0 00 02 70 0E

Response is: 09 04 04 E0 00 00 00 44 33

4.7.4. Preset multiple registers (FC16)

Function code 06 (FC16) is used to activate functionalities of the Gripper (robot output). Examples of such data are action request, speed, force, etc.

Example of setting multiple registers FC16:

This message requests to set position request, speed and force of the Gripper by setting register 0x03E9 (1002) and 0x03EA.

Request is: 09 10 03 E9 00 02 04 60 E6 3C C8 EC 7C

Response is: 09 10 03 E9 00 02 91 30

4.7.5. Master read & write multiple registers FC23

Function code 23 (FC23) is used for reading the status of the Gripper (robot input) and activating functionalities of the Gripper (robot output) simultaneously. Examples of such data are Gripper status, object status, finger position, etc. Action requests are speed, force, etc.

Example of reading and writing multiple registers FC23:

This message reads registers 0x07D0 (2000) and 0x07D1 (2001), which contains Gripper Status, Object Detection, Fault Status and Position Request Echo. It also sets the position request, speed and force of the Gripper by writing to registers 0x03E9 (1001) and 0x03EA (1002).

Request is: 09 17 07 D0 00 02 03 E9 00 02 04 00 E6 3C C8 2D 0C

Response is: 09 17 04 01 00 09 E6 F6 C1

Note that the content of the response might change depending on the Gripper's status.

4.7.6. Modbus RTU example

This section depicts the example from the Control Logic Example section, when programmed using the Modbus RTU protocol. The example is typical of a pick and place application. After activating the Gripper, the robot is moved to a pick-up location to grip an object. It moves again to a second location to release the gripped object.

Step 1: Activation Request ( clear and set rACT)

Request is (clear rAct): 09 10 03 E8 00 03 06 00 00 00 00 00 00 73 30

Response is: 09 10 03 E8 00 03 01 30

Request is (set rAct): 09 10 03 E8 00 03 06 01 00 00 00 00 00 72 E1

Response is: 09 10 03 E8 00 03 01 30

Step 2: Read Gripper status until the activation is completed

Request is: 09 03 07 D0 00 01 85 CF

Response (if the activation IS NOT completed): 09 03 02 11 00 55 D5

Response (if the activation IS completed): 09 03 02 31 00 4C 15

Step 3: Move the robot to the pick-up location

Step 4: Close the Gripper at full speed and full force

Request is: 09 10 03 E8 00 03 06 09 00 00 FF FF FF 42 29

Response is: 09 10 03 E8 00 03 01 30

Step 5: Read Gripper status until the grip is completed

Request is: 09 03 07 D0 00 03 04 0E

Example of response if the grip is not completed: 09 03 06 39 00 00 FF 0E 0A F7 8B

Example of response if the grip is completed: 09 03 06 B9 00 00 FF BD 00 1D 7C

Step 6: Move the robot to the release location

Step 7: Open the Gripper at full speed and full force

Request is: 09 10 03 E8 00 03 06 09 00 00 00 FF FF 72 19

Response is: 09 10 03 E8 00 03 01 30

Step 8: Read Gripper status until the opening is completed

Request is: 09 03 07 D0 00 03 04 0E

Example of response if the opening is not completed: 09 03 06 39 00 00 00 BB 10 30 E0

Example of response if the opening is completed: 09 03 06 F9 00 00 00 0D 00 56 4C

Step 9: Loop back to step 3 if other objects have to be gripped.

4.8. Control over TM

4.9. Control over OMRON TM

4.10. Control over Universal Robots with URCaps

The URCap package contains many features to program and control the Gripper. The package provides:

• Gripper toolbar: The Gripper toolbar is automatically installed with the URCaps package. It allows jogging and testing of the Gripper. It is a great tool to try grasps with the Gripper while programming.
• Gripper node: The URCaps package adds a Gripper node that is used to add a Gripper command. A node can make the Gripper move to a specific opening, grasp an object and modify the speed and force applied by the Gripper.

4.10.1. Gripper Dashboard

4.10.1.1. Overview

Single Gripper

Open or create a robot program

1. Go the Installation tab
2. Select Gripper in the left pane
3. Tap the Dashboard button
4. In no Gripper is found, tap the Scan button to detect any Gripper that might be connected to the robot
5. Tap the Activate button

Fig. 4-3: Gripper Dashboard (steps highlighted)

6. If required, change the ID of the Gripper; ID numbers range from 1 to 4

Fig. 4-4: Gripper ID modification in the Gripper Dashboard

Multiple Grippers

For each Gripper connected, follow steps 3 to 6 set out in the Single Gripper section.

4.10.1.2. Features

4.10.2. Gripper Calibration menu and wizard

Depending on the fingers/fingertips used, the operator will calibrate the Gripper and measure the stroke by defining the fully open and fully closed positions.

Make sure the Gripper is activated.

1. Go to the Installation tab
2. Select Gripper in the left pane

1. Tap the Calibration tab
2. Tap the Calibrate button corresponding to the Gripper you want to calibrate

Tapping the Calibrate button in the Gripper Calibration menu launches the Calibration wizard.

Follow the instructions on the screen of the teach pendant.

Fig. 4-5: First step of the calibration wizard

Fig. 4-6: Second step of the calibration wizard

Following their respective calibration, the Grippers will display their actual stroke, from the fully closed to the fully open position.

Fig. 4-7: Single Gripper, calibrated

4.10.2.1. Features

4.10.3. Gripper Toolbar

The Gripper Toolbar is generally used to test and jog the Gripper, meaning it has no effect on the programming of the robot.

4.10.3.1. Overview

Prior to using the Gripper Toolbar, the user needs to go to the Gripper Dashboard and tick the Show Gripper Toolbar. Please refer to the Gripper Dashboard section

Right after the installation of the Gripper URCap, a collapsed Gripper toolbar will display at the top of the screen; please refer to the figure below.

Fig. 4-8: Gripper toolbar (collapsed)

An expanded Gripper Toolbar prior to the activation of the Gripper looks like the figure below:

Fig. 4-9: Gripper Toolbar before activation

• Tap the Activate button to enable the Gripper

Single Gripper

Once the Gripper is activated, the toolbar can be expanded and used to test and jog the Gripper

Fig. 4-10: Gripper toolbar after activation

Multiple Grippers

If multiple Grippers are used, check one or several Grippers and test their settings and features.

Fig. 4-11: Gripper toolbar (expanded, multiple Grippers)

4.10.3.2. Features

Gripper activation

Gripper operation window

4.10.3.3. Show/hide Gripper Toolbar

It is possible to toggle between a shown and a hidden Gripper Toolbar.

1. Create or load a robot program
2. Tap the Installation tab
3. Select Gripper in the left pane
4. Tap the Dashboard submenu
5. Check/Uncheck the box in the lower left corner

4.10.4. Gripper Node

To add and edit a Gripper node inside your robot program, follow the steps below:

1. Tap Program Robot.
2. Open an empty program or load one.
3. Go the Structure tab and tap the URCaps submenu.
4. Tap the Gripper button.
5. Go to the Command tab to edit the Gripper node inserted.
6. Tap the Edit action button to edit the node's parameters.

4.10.4.1. Command window

The Command window shows the requested action parameters for the Gripper node. Depending on the position, speed and force parameters, warning messages may display.

To edit the Gripper node, tap Edit action (please refer to the Edit action screen section for more details).

Features

4.10.4.2. Edit action screen

Tap Edit action from the Command window and use the Edit action screen to edit the Gripper’s parameters and adjust its position, speed and force. In normal usage conditions, the Gripper will move as soon as you change the position setting. The Gripper will not move if it is not properly powered, connected and activated.

Single Gripper

Fig. 4-12: Edit action screen

Multiple Grippers

Features

4.10.4.3. Grip Check node

In order to add and edit a Grip Check node:

1. Open a robot program or create one
2. Go to the Installation tab
3. Tap the URCaps submenu
4. Select Grip Check

TheGrip Check node is pre-packaged as an If statement that prompts the user to select between if the object is detected and if the object is not detected.

Selecting the former option allows the user to check a box and choose whether or not the grasp should be validated according to the object's dimension (in percentage if the Gripper is not calibrated, or in mm/in if the Gripper is calibrated—depending on the PolyScope configuration).

Fig. 4-13: Grip Check node interface

Fig. 4-14: Grip Check node interface with dimension validation

Given that the Grip Check node is an If statement, tapping the actual node in the Command tab brings up the option to add an Else instruction to the program tree.

4.10.4.4. About

In this window, the user can access information such as the Gripper's hardware, software and firmware versions, the number of cycles completed by the device and more.

1. Create or load a robot program
2. Tap the Installation tab
3. Select Gripper in the left pane
4. Tap the About submenu

If the Gripper version is obsolete, a warning message will display and an Upgrade firmware button will prompt the user to upgrade the firmware to the latest available version.

Fig. 4-15: Firmware Upgrade Warning Message in PolyScope for CB-Series

4.10.4.5. Error messages overview

If a program is running without the Gripper being activated, the program will stop at the execution of a Gripper node and the following message will be displayed in a popup. Tap Stop Program and activate the gripper with the toolbar to continue or add an activation command in the program (please refer to the Advanced Gripper Functions section).

4.10.4.6. Gripper Program Template

With the URCap package installation, a program template will automatically be installed in the program folder of PolyScope. It contains comments and pop up windows that explain Gripper nodes and advanced functions.

Load and open the gripper_tutorial.urp program located in the root program folder. Make sure the Gripper is well connected to the UR controller. Run the program. You will see pop up windows with comments on the Gripper nodes and advanced functions.

4.10.4.7. Advanced Gripper Functions

The use of Gripper URCap nodes allows to move the Gripper and modify its speed and force. However, some advanced functions are only available through UR Script commands.

The functions listed below can be called using subprograms in PolyScope or with a script. Functions with the suffix _and_wait will wait for the Gripper to complete its operation before going to the next step.

Single Gripper

Multiple Grippers

Here is an example of how to use the script commands with more than one gripper.

Fig. 4-16: Example of UR script commands with multiple Grippers

The functions listed below can be called using subprograms in PolyScope or with a script. Functions with the suffix _and_wait will wait for the Gripper to complete its operation before going to the next step.

4.10.5. Retro-compatibility of URCaps with legacy driver programs

The Gripper URCap can be used within programs that were made with the legacy driver package. To do so, you need to do the following modifications:

1. Open your .urp program in PolyScope and execute it.
   1. You should see an error message that tells you that some functions are double defined. This is because the URCap embeds the functions directly in the program preamble, so there is no need for a BeforeStart section.
2. Comment all the lines of the BeforeStart section from your older .urp program.
   1. You will still get an error. It arises because we changed some functions names due to a naming conflict.
3. To solve the problem, you can either suppress those functions or rename them.

Fig. 4-17: Older program's subprograms to suppress or rename to use with URCaps package.

Here is the list of the functions that were renamed:

• rq_print_fault_code -> rq_print_gripper_fault_code
• rq_print_num_cycles -> rq_print_gripper_num_cycles
• rq_print_driver_state -> rq_print_gripper_driver_state
• rq_print_firmware_version -> rq_print_gripper_firmware_version
• rq_print_driver_version -> rq_print_gripper_driver_version

4.11. Control over Universal Robots without URCaps

If your Universal Robots controller is not compatible with the URCap package (see Installation for Universal Robots section) for compatibility), you can install the driver package. This package allows programming of the Gripper with scripts in a PolyScope program. It includes program templates and examples to help you get started with your own custom program. It also contains the Gripper toolbar for jogging and controlling the Gripper.

4.11.1. Gripper Toolbar

4.11.1.1. Overview

The Gripper toolbar is automatically installed with the driver package. The Gripper toolbar allows you to jog and test the Gripper. It is a great tool to try grasps with the Gripper while programming.

Toolbar collapsed	Toolbar expanded, Gripper activation window	Toolbar expanded, Gripper operation window :
Tap the Gripper button to expand the toolbar.	When the Gripper is not activated, the toolbar shows this window. You need to tap the Activate button to be able to jog the Gripper. Emergency open and close allows you to control the Gripper without activating, this mode will use a very low speed and force setting	Use the buttons of this window to jog and test the Gripper.

4.11.1.2. Features

Toolbar collapsed

Toolbar expanded

When communication with the Gripper is not established, the expanded toolbar shows the driver version:

Fig. 4-18: Gripper toolbar expanded with driver version

4.11.2. Demo Scripts

The following section details the demo scripts provided with the driver package.

pick_and_place_demo_with_subprograms.script is a demo script for pick and place applications using provided subprograms. The script uses subprograms included in the package such as rq_set_force, rq_set_speed, etc.

The script uses rq_speed and rq_force as speed and force parameters to be used during the program. They can be modified using values from 0 to 255 (please refer to the Provided Variables and Functions section).

The script executes the following actions in sequence :

• Assign initial values to the global variables in the Init Variables section.
• Initiate the communication with the Gripper in the BeforeStart section.
• The Robot Program section contains the commands sent to the Gripper:
  • Activate the Gripper with SubP_rq_activate_and_wait.

  Info

  Remember that all _and_wait subprograms will wait for the action to be completed before going to the next step.

  • Move the robot to a predetermined position

  Tip

  Run with Universal Robots simulator first or make sure that the UR robot work area is totally cleared before running the script, as it will move the robot.

  • Close the Gripper with rq_close_and_wait.
  • Watch for object detection status:
    • If an object is detected, the script moves the robot and opens the Gripper.
    • If no object is detected, the script prompts a warning

.pick_and_place_demo_async_partial_opening_without_subprograms.script is similar to the previous demo, but without using subprograms. This demo uses asynchronous commands so that the robot and the Gripper will move at the same time (the previous example had the Gripper and the robot move separately).

4.11.3. Custom Programs

You can create your own program that commands the Gripper with the provided templates :

• Open basic_template.script in the list of provided templates;
• Push play to test the Gripper. The program will activate the Gripper and then do a loop of closing and opening the Gripper;
• Add your instructions under the robot program section. Program instructions can be added with PolyScope.

As shown in the figure below, the basic_template program will execute these instructions in a sequence:

• Assign initial values to the global variables with the Init Variables section.
• Initiate communication with the Gripper with the Before Start section.
• The Robot Program section contains the commands sent to the Gripper:
  • Activate the Gripper with SubP_rq_activate_and_wait.
  • Close the Gripper with rq_close_and_wait.
  • Open the Gripper with rq_open_and_wait.

Fig. 4-19: Basic template as shown in UR PolyScope.

When using the advanced_template, you have access to all of the subprograms listed in the Provided Variables and Functions section. Unused subprograms can be removed from the list. You must use global variables to pass information, not arguments.

4.11.4. Provided Variables and Functions

The file rq_script.script contains function definitions and variables that enhance the programming of the Gripper. Here is the list of these variables and functions.

Variables are used when programming the Gripper using subprograms. Since it is not possible to pass arguments to subprograms, the global variables listed below must be used.