Programming a robot by demonstration for routing applications using a portable CMM

Despite the availability of many software solutions for programming industrial robots, many tasks in robotic manufacturing applications are still programmed using the teach pendant, an operation that is both time consuming... [ view full abstract ]

Despite the availability of many software solutions for programming industrial robots, many tasks in robotic manufacturing applications are still programmed using the teach pendant, an operation that is both time consuming and that often relies on empirical expertise for precision assessment. This is often the result of a fallback due to the lack of available CAD for the part to be manufactured which would be used in an Off-Line Programming(OLP) approach. Alternatives to using the teach pendant for programming parts with no reference CAD model include reverse engineering using 3-D scanning technology or sophisticated vision-based feature recognition algorithms. A relatively new robot programming paradigm, programming by demonstration proposes an approach for robot programming that provides an interface between the robot and the programmer that is more intuitive than a teach pendant or using OLP packages. Examples of programming by demonstration include the operator directly guiding the robot end-effector to desired locations, or the recording and playback of the task as executed by a trained expert using motion capture technology.

This paper presents a novel implementation of programming by demonstration using a portable coordinate-measuring machine for robotic routing applications (no CAD model), with several advantages over COTS programming by demonstration solutions.
In this implementation, an operator traces the contour of a complex 3-D part delimited by the fixture holding the part to be routed. Using this path information, the 6-D cartesian coordinates of the trajectories are computed. Since the process is axisymetric (5-D) a redundancy optimisation is then performed and robot trajectories and corresponding robot code are automatically generated and validated via a 3-D graphical interface implemented using the Robot Operating System (ROS).

The system allows an operator to fully program a part from tracing the contour to execution by the robot under 20 minutes. The approach was validated on an industrial robot using actual test parts and a prototype system is now running at the client's premises.