Modern industrial robots have been utilized in a huge range of small- and medium-scale applications, but very large-scale problems such as those encountered in aerospace manufacturing, ship building, wind turbine manufacturing, and construction have seen limited adoption. A typical approach for large-scale solutions is to mount a standard manipulator on a gantry or rail system; however, this approach is often prohibitive because of cost, limited accuracy or inability to access complex structures and parts.
To expand robotics for new large-scale applications, SwRI has developed a mobile manipulator system that utilizes remote position sensing of the end-effector to accurately operate over a large work envelope. For this program SwRI's goal was to utilize an off-the-shelf industrial manipulator, mobile platform, and metrology system.
Potential Mobile Manipulator Applications
- Processing or assembly of large-scale parts such as wind turbine blades or towers
- Surface processing (sanding, coating removal, or painting) of large systems such as aircraft or ships
- Welding of large-scale parts and components
- Nuclear, biological, or chemical decontamination
- Large-scale rapid prototyping
A variety of off-the-shelf robotic manipulators, mobile bases and position sensing approaches could be utilized to adapt the system for a specific application. For this demonstration, SwRI utilized the following:
|Motoman Robot||SIA-20 seven degree-of-freedom robot arm|
|Vetex Mobile Platform||Omni-directional mobility platform|
|Nikon Metrology iGPS||Measurement system for tracking multiple objects within a large work space with high accuracy and in real-time|
Related YouTube Videos
Mobile Robot Capabilities
The demonstration videos provided in the links above illustrate the following mobile robot capabilities:
- The ability to coordinate platform and manipulator motion during a six degree-of-freedom path following task on an aerospace part (T-37 elevator).
- The ability to auto-generate a path plan based on known 3-D geometry and 3-point part registration data. The robot can work on the part no matter where it is located as long as the part is within reach. The videos show the robot working on the wing at different heights and angles. Part registration was performed using the wireless hand-held probe shown in the video.
- The ability to incorporate laser metrology feedback in-process for both platform and tool point correction, achieving a maximum error magnitude of ~½ inch, which is required for the intended applications. The cylindrical laser sensors on the tool and platform provide six degree-of-freedom frame data.
- Note that in the future, accuracy could be dramatically improved through the incorporation of inertial sensors to overcome signal latencies. Processes for which the mobile platform is stationary while manipulator is in motion could achieve accuracies better than 1 mm without any additional hardware.
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