Master Thesis - Hochschule Bonn-Rhein-Sieg

7. Conclusion and Outlook Master Thesis Björn Ostermann page 115 of 126
7 Conclusion and Outlook
7.1 Conclusion
This work shows new ways towards a collaborative workplace, using a 3D camera and a PC program,
to allow an industrial robot and humans to work alongside each other.
Two approaches towards this goal have been implemented in the course of the project. The first is a
speed control based on proximity monitoring. The second is a path planning algorithm that plans a
collision free trajectory of the robot arm, based on the location of dynamic objects, the position of the
robot and its goal.
The resulting demonstrator, programmed during the course of this work, uses both approaches
separately, demonstrating their functionality. The developed workplace has been successfully
demonstrated during presentations at the BGIA and has proven to function reliably. While still tasks
remain for further studies (see chapter 7.2), the stability of the system was seldom disturbed by outside
influences. Only two specific pieces of clothing (a grey jeans and a black shirt) proved to be
problematic to the developed algorithm because of their unexpected values from the 3D camera’s
measurement.
Due to a problem in the external control mode of the robot, which is caused by the robot’s PLC, the
robot tends to judder if goal changes occur in the direct drive mode. This has no influences on the
functionality but only in the smoothness of the path execution in this mode.
The algorithms, the PC and the sensor equipment used in the demonstrative workplace have not been
designed towards the necessary safety, but have only been implemented for this case study. The safety
of the system at this stage is ensured by the application of a hold to run button.
If the complete project is implemented for industrial purpose and both approaches are combined, only
the control of the robot’s speed needs to be safe. The trajectory will only allow the robot to use its full
potential. The advantage of this approach, other than the reduced demand on the safety of the planning
of the trajectory, is that the algorithm of the trajectory planning can be changed afterwards without
reevaluation of the safety of the whole system.
As chapter 6.3 showed, the system is not ready for industrial application at this point. In chapter 6.5 a
conclusion was formulated from the observed performances, resulting in the observation that the
designed system, implemented in special hardware, could be used to control a robot at 2 m/sec with a
safety distance of 500 mm.