Canadian robotics software provider RoboDK has launched TwinTool, an application that offers fully automated robotic tool calibration for industrial robots. TwinTool is an economical, quick and easy solution for improving tool accuracy in a wide variety of manufacturing applications. It is a competitive alternative to the expensive and complex robot calibration services currently available on the market.
Industrial robots are increasingly used for high-precision manufacturing tasks, such as assembly, welding and machining. However, new users are sometimes disappointed by the apparent low accuracy of their robots. They invest in expensive robot calibration systems to try to improve accuracy.
Albert Nubiola, CEO of RoboDK, explains that this is not always necessary:
“Many users do not realize how important it is to calibrate the tool correctly. They think that they have to calibrate the whole robot. However, calibrating the tool center point (TCP) correctly can bring a significant improvement in accuracy.”
Repeatable, not precise: the problem of industrial robots
Industrial robots have high repeatability, but low precision. This means that they can move to the exact same position every time (repeatability), but their position does not exactly match the world coordinate system (accuracy).
There are two main types of calibration procedures to improve the accuracy of a robot. Robot calibration requires precision laser systems to calibrate the robotic mechanism itself. Tool center point (TCP) calibration is a simpler procedure to ensure that the programming system has an accurate model of the robot tool.
Samuel Bertrand, software developer at RoboDK, explains:
“TwinTool is a fast and affordable solution to automatically calibrate the robot’s TCP compared to other solutions such as laser trackers. Laser calibration is expensive and many robot applications do not need such precision.”
TwinTool performs tool calibration with a ready-to-use sensor
The typical way to calibrate a robot tool center point (TCP) is by a 4-point method, which involves taking a series of at least 4 joint readings while moving the tool to the same point with orientations different. This process is time consuming and less precise because the user has to manually move the robot to different positions.
TwinTool’s calibration functionality is distributed as a RoboDK application, a plug-in that extends the capabilities of RoboDK’s popular robot programming software.
RoboDK TwinTool requires a standard Linear Gauge Sensor (or LVDT) to communicate directly with any robot and to calculate the robot’s Tool Center Point (TCP) without human intervention. TwinTool automatically records an unlimited number of points and the linear gauge sensor provides high precision for tool definition.
The application is compatible with a wide range of sensors from major brands such as Mitutoyo, KEYENCE and Sylvac, which allows it to be versatile with any hardware. Other brands of sensors can also be integrated on request.
RoboDK TwinTool supports over 600 robot arms from 50 different robot manufacturers and is suitable for many industrial environments.
This follows RoboDK’s well-established philosophy of remaining brand-agnostic for hardware.
Ease of use and safety at the heart of the process
Equally important, RoboDK places great importance on the ease of use and security of its products. TwinTool runs directly from RoboDK, bridging the robot controller and the sensor. No programming skills are required. Users only need the RoboDK simulation software, a robot, its tool (spherical or conical) and a sensor. Singularities and collisions are avoided and trajectories automatically calculated.
“We have created a user-friendly wizard to ensure that the calibration is carried out correctly and safely,” explains Samuel Bertrand. “It’s simple enough to be used by operators who don’t have robotics knowledge.”
To calibrate a robot tool, the user simply follows this 3-step procedure in the RoboDK software:
1. Select their robot model from RoboDK’s extensive robot library.
2. Connect RoboDK to robot and sensor.
3. Move the robot over the sensor and start the calibration.
Albert Nubiola says:
“The procedure is fully automated and requires no manual intervention. It automatically avoids collisions and does not require users to write a single line of code.”
Accuracy to 0.250mm
With TwinTool, users can quickly and automatically improve their tool accuracy by up to 0.250mm with certain robot configurations. This improves accuracy by 2 to 10 times, depending on the robot and the tool.
“Without this calibration”, explains Albert Nubiola, “the errors of the robot can be in the range of 2-5 mm. With this calibration of the tool, you can generally reduce the errors of the robot down to 0.250-1 mm depending on your application.”
This improvement in precision is more than enough for most robotic applications, even those that require precision. This can save users a lot of money on unnecessary robot calibration services.
Users can now request to add TwinTool to their copy of RoboDK software as an optional RoboDK application.
Bertrand explains that they will continue to improve the functionality of TwinTool. “Currently, the tool is geared towards maintenance modes,” he says. “However, we are working towards a mode that will automatically run the calibration procedure during production.”
RoboDK also plans to expand its app interface by creating a RoboDK App Marketplace. They will invite companies to develop and publish their own applications for the software.
Founded by Albert Nubiola in January 2015, RoboDK is a spin-off from the very prestigious CoRo laboratory at ETS University in Montreal, Canada. RoboDK software is designed to bring powerful simulation and robotic programming capabilities to businesses large and small, as well as coders and non-coders. Today it supports over 600 robots from 50 different manufacturers, including ABB, Fanuc, KUKA, Yaskawa/Motoman, Stäubli and Universal Robots.
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