Improving the accuracy of industrial robots

The high load capacity, large work space and low investment costs of industrial robots offer a unique potential to reduce costs in numerous areas of production. However, many interesting applications can only be implemented cost-effectively if measures are taken to improve their accuracy.

Services

• Pre-tests to determine achievable accuracy levels
• Integration of sensors measuring relative or absolute positions to enhance accuracy
• Development of compensation models (e.g. deformation models, kinematic models) to improve positioning accuracy
• Geometric calibration of robot cells, robots and robot tools
• Design, development and implementation of measures to enhance the accuracy of new or existing systems

Technologies

Fraunhofer IPA develops software modules and methods to improve robot accuracy:

• Compensation for deviations in paths and positions via measurement value feedback (e.g. laser tracker, stereo camera system)
• Robot referencing software to calibrate the robot from component features by matching point clouds
• Rigidity model for 6-axis industrial robots to compensate for payload-related deviations
• Software and methods for accurately calibrating robots and peripheral equipment

Advantages

Although robots have a very high repeat accuracy, their absolute accuracy is not so good. Absolute accuracy can be improved by making technical modifications. This opens up new application fields and offers numerous advantages:

• Implementation of robots for machining tasks with low to average accuracy requirements. Compared to tooling machines, robots are more economical and also have a better orientation capacity
• Automation of rework tasks (e.g. deburring, rounding)
• Improved quality does away with the need for downstream processes
• Robots are programmed faster because manual re-teaching with offline programming is no longer required; the system can also be integrated into the company’s CAD/CAM tool chain