Safety Function Blocks for Workspace Monitoring

As the synergy between humans and robots deepens, ensuring a safe working environment is paramount. In the LASAL SAFETYDesigner from SIGMATEK two new function blocks, in combination with our MDD 2000 servo drives, the Safety CPU SCP 211 and the safety functions SLS (Safely Limited Speed) and SP (Safe Position), offer tailored workspace monitoring for all serial kinematics: "Denavit-Hartenberg (DH) Transformation" and "Collision Detection." The user only has to set the appropriate parameters to be able to use these functions in his project.

DH Transformation

The DH Transformation block transforms a spatial coordinate system at the input into a spatial coordinate system at the output. A multi-axis robot arm can be realized by using the module several times. The location coordinate system at the output of this chain represents the TCP (Tool Center Point) of the robot.

Collision Detection

The Collision Detection function block was developed to detect a collision between the Tool Center Point (TCP) of a robot and other objects. The workspace is defined by the minimum and maximum XYZ coordinates. These two points span a cuboid that is parallel to the coordinate system. This workspace is the area in which the TCP is allowed to move. In addition, an enveloping sphere is placed over the current position of the robot.

Collision detection permanently monitors the valid area and detects collisions by comparing the enveloping sphere with the defined workspace limits. If the robot moves outside this defined range, the user can program what happens in this case, e.g. whether an emergency stop is triggered or another error reaction.

By linking individual workspaces, it is also possible to create complex workspaces.