Final Project Report:

NSF PII award #0849008

October 15, 2011

James W. Beard, PI

“Developing a Mobile, Robotic Welding System”

Executive Summary:

This is the Final report for the project award 0849008 , “Developing a Mobile Robotic Welding System” covering the period 2/1/09 through 10/15/11. This project includes the original STTR Phase II award and the TECP supplement. This report serves as the final report for both activities.

Many industries such as large shipbuilding and site-based fabrication and construction do not lend themselves to traditional assembly line robotic systems. Large military ships, for example, tend to be unique with each successive ship manufactured having different characteristics. The size and scale of a typical ship combined with the high costs associated with dry-docks or real-estate immediately adjacent to the launch location has led toward a common manufacturing technique in which the structural components of the ship are assembled in multiple locations with only the final assembly occurring in the most expensive location. We call these “unstructured environments” because the building process is not regular (i.e., is not highly dimensionalized). Robotic systems in these environments must be mobile, flexible and adaptable. This creates a unique set of challenges that this project has addressed.

Mobile robotics (robotic systems capable of navigating through the environment to perform motion control tasks) provides new opportunities to improve worker productivity in unstructured environments. Robotic Technologies of Tennessee (RTT) and its University partner, Tennessee Technological University (TTU) have a history of developing automated mobile robotic platforms in unstructured environments such as the power production and shipbuilding industries. Under the NSF STTR program, Robotic Technologies of Tennessee (RTT) has developed and commercialized a climbing mobile robotic welding system suited for welding in unstructured environments such as shipyards or construction of large structures. This system is called the Mobile Robotic Welding System (MRWS). The MRWS is capable of mechanizing weld processes while operating in inverted positions, even upside down.

When compared to manual welding processes or track based automated systems, the MRWS increases productivity, safety and quality. This system allows the weld technician to perform the weld process remotely making the job safer and more comfortable for the operator. This tends to reduce work place injuries related to repetitive motion and flying debris. In addition, the ability to control the welding from a control device allows the worker to remain in a comparatively better ergonomic position which enables older and less physically healthy welders to perform in their jobs longer. Finally, the MRWS better matches the expectations of younger generations of workers giving industrial recruiters a better chance of attracting young workers to join the industry (i.e., the industry is having trouble finding workers).

This system has been approved and qualified for the most stringent welding processes (NAVY requirements for ships) by several Tier-I shipbuilding manufacturers. Two commercial versions of the MRWS have been developed under the NSF STTR program. These systems are in use at the largest US shipyards. RTT’s mobile robotic welding systems have been a featured technology of the National Shipbuilding Research and have been featured at several industry forums (Shiptech 2009 – 2011, Fabtech 2010, 2011).

The primary commercial focus for the RTT team is to achieve broad-based support from shipyards, demonstrated through regular use, commitment to the product, and a target level of sales. As the project ends, RTT is well on the way to achieving this broad-base support. We are currently negotiating with several large manufacturing companies to identify an appropriate teaming agreement.

Commercialization and Dissemination: The team has been active in building shipyard support to move toward partnership with a commercialized product as discussed above, with formal meetings held with new product development personnel from ESAB and Illinois Tool Works, the parent company of Miller and Fronius. RTT has been regularly invited to present at ShipTech. Shiptech is a avy sponsored meeting for all shipyards. At the Shiptech 2011 meeting, RTT hosted a workshop on robotic automation for shipbuilding with nearly 30 shipyard personnel in attendance.

In summary, the milestones planned for this project have been met. RTT has reached a commercialization stage and is making sales and supporting product in the field. RTT has established one distributor in the Gulf-Coast region. RTT is pursuing a teaming agreement with a larger manufacturer to expand the rate of growth of unit sales and to target larger (national, worldwide) markets. A collection of photographs showing RTT’s MRWS in production are including in the following figures.

The remainder of this report will summarize the progress on all tasks associated with the project. This is first summarized in a table that lists tasks, deliverables, dates completed and percentage complete. A detailed discussion of each task and the work performed on each task is provided in appendix A, Summary of work on project tasks.

Fig. 1 Advanced MRWS-100 in Production


Light weight, portable, highly mobile system for remote welding

Operator performing weld remotely with Control Pendant Arc Viewing

1. Summary of Project Tasks and Subtasks:

The overall progress toward the project tasks are summarized in the following table, with the last two columns indicated the percentage and date completed. The table is color coded as follows:

Tasks Completed
Tasks Underway
No Significant Progress Yet

Table I: Summary of Progress on Project Tasks:

Task / Task Description / % complete / date completed
Objective I: Advance Climbing Robot Platform
Task I.1 / Perform advanced modeling and design on platform suspension components to prepare for in-field climbing surface conditions. / 100% / 8/15/09
Task I.2 / Evaluate and optimize material performance in tandem with kinematic design of the suspension components to survive extended in-field conditions. / 100% / 8/15/09
Task I.3 / Design the MRWS platform to meet the shipbuilder requests of outdoor operation and reduced system weight. / 100% / 8/15/09
Task I.4 / Create advanced model of magnetic fields created by the robot tractive members and the weld arc, and use in advanced prototype design. / 100% / 8/15/09
Deliverables / 1.  Enhanced prototype MRWS robot platform design meeting the performance and requirements specified by the shipbuilders.
2.  Multiple design options for locating welding torch manipulator / 1-100%
2-100% / 8/15/09
Objective II: Advance Design of Torch Manipulator
Task II.1 / Extend the kinematic and dynamic models of the torch manipulator to include the effects of compliance on the system. / 100% / 8/15/09
Task II.2 / Explore advanced inverse dynamic control algorithms and mechanical designs to isolate dynamic disturbances at the torch tip. / 100% / 8/15/09
Task II.3 / Incorporate precise and repeatable torch work travel, depth, work angle, and travel angle adjustments into the torch manipulator. / 100% / 8/15/09
Task II.4 / Design the torch manipulator for easy access by operators to the weld torch / 100% / 8/15/09
Deliverables / 1.  Torch manipulator design with enhancements to improve performance and usability in the field. / 100% / 8/15/09
Objective III: Advance Robot Control and Navigation System
Task III.1 / Define the expected conditions the control system will have to overcome in the field tests. / 100% / 8/15/09
Task III.2 / Develop a navigation and control algorithm to accommodate non-ideal conditions defined in III.1. / 100% / 8/15/09
Task III.3 / Develop class of additional autonomous behaviors needed to handle in-field conditions (e.g., alignment to weld seam, start and stop, obstacle avoidance) / 100% / 8/15/09
Task III.4 / Implement the control and navigation system into the advanced MRWS prototype / 100% / 8/15/09
Deliverables / 1.  Advanced MRWS control and navigation system capable of handling real-world conditions in manufacturing environment / 100% / 8/15/09
Objective IV: Seam Tracking and Identification System
Task IV.1 / Using the lessons learned from the Phase I vision system, develop criteria to be met in the new vision system design. / 100% / 8/15/09
Task IV.2 / Create basic overview of vision system design, select parts from COTS components as available, integrate with the MRWS platform. / 100% / 12/15/09
Task IV.3 / Develop image processing algorithms (combination of commercial algorithms and modules developed by RTT) to identify the shape and centerline of the weld seam. / 100% / 6/15/10
Task IV.4 / Create interface between output from image system and robot control algorithm / 100% / 8/30/09
Task IV.5 / Combine all hardware and the software developments and incorporate on to the advanced MRWS prototype / 100% / 6/15/10
Deliverables / 1.  Hardware selection, image processing algorithms, system embedded on robot platform
2.  MRWS advanced prototype complete with tracking system based on operator feedback / 100 % / 6/15/10
Objective V: Develop Human-Robot Interface (HRI) for Multi-DOF Welding System
Task V.1 / Collect additional input on necessary control functions and desired formats of HRI as well as the desired information to be reported from the robot system. / 100% / 3/15/10
Task V.2 / Incorporate hardware to allow the operator to setup and control the vision seam tracking system (tasks described Objective 4) from the HRI. / 100% / 3/15/10
Task V.3 / Design the layout of the HRI to effectively present all control parameters and minimize the overall size of the unit. / 100% / 3/15/10
Task V.4 / Incorporate into the HRI the ability for the robot to provide feedback to the operator during the weld process. / 100% / 3/15/10
Deliverables / 1.  Design of rugged, compact HRI suitable for use with MRWS advanced prototype during the extended field tests. / 100% / 3/15/10
Objective VI: Meet Weld Cert. Requirements and Remote Weld Viewing Capability
Task VI.1 / Select a camera system that offers a suitable picture of the welding process in the immediate vicinity of arc. / 100% / 6/15/10
Task VI.2 / Integrate the camera on to the MRWS, iterating to find the ideal position yielding the best viewing angle for visual characterization of the weld. / 100% / 6/15/10
Task VI.3 / Collect input from welders and repeat VI.2 to satisfy their requirements. / 100% / 6/15/10
Task VI.4 / Provide the video data to the operator though integration with the robot control pendant. / 100% / 12/15/10
Deliverables / 1.  Identified camera system for MRWS platform.
2.  MRWS platform with the camera integrated and feedback provided in the robot control pendant. / 100 % / 3/15/10
Objective VII: Fabricate Advanced Prototypes of the MRWS Ready for Extended, In-Field Testing
Task VII.1 / Fabricate all components of the MRWS prototypes for the extended field tests / 100% / 3/15/10
Task VII.2 / Assemble advanced MRWS prototype / 100% / 8/30/10
Deliverables / 1.  Advanced MRWS prototype (1-3) ready for field testing. / 100% / 8/30/10
Objective VIII: Prove MRWS in the Extended In-Field Tests
Task VIII.1 / Develop the extended, in-field test plan. / 100% / 3/15/10
Task VIII.2 / Perform first stage tests, (advanced in-lab tests), modify platform design as needed / 100% / 5/15/10
Task VIII.3 / Perform second-stage (primary) tests, Define details of environment for field testing. / 100% / 6/30/10
Task VIII.4 / Perform qualification tests on MRWS in-field / 100% / 3/30/10
Task VIII.5 / Perform in field testing at commercial shipyard / 100% / 2/15/11
Task VIII.6 / Modify platform design based on evaluation of in-field testing / 100% / 3/1/11
Deliverables / 1.  Results from laboratory testing or MRWS.
2.  Results from field testing at commercial shipyard in a production environment.
3.  Enhanced prototype MRWS platform with extensive field history. / 100% / 3/1/11
Objective IX: Explore Future Commercialization Opportunities
Task IX.1 / Document the requirements for the new applications and design modifications. / 100% / 6/1/11
Task IX.2 / Develop a path to commercialization by building on current market development. / 100% / 6/1/11
Deliverables / 1.  Plan to upgrade and extend platforms to two advanced applications.
2.  Commercialization plan for these two products / 100% / 6/1/11
Objective X: Technology Transfer, Dissemination and Final Reporting
X.1 / Disseminate project results through industry panels, appropriate conference or journal, market development activities / 100% / 8/1/11
X.2 / Prepare final reporting material / 100% / 10/15/11
Deliverables / 1.  Executed dissemination plan
2.  Final report / 100% / 10/15/11
TECP Objective I: Adapt MRWS system for control of inspection transducer
TECP I.1 / Reconfigure existing MRWS manipulator to meet NDE requirements / 100% / 6/15/11
TECP I.2 / Reconfigure MRWS to adapt commercial transducers / 100% / 6/15/11
TECP I.3 / Test positioning requirements / 100% / 6/15/11
TECP I.4 / Evaluation system / 100% / 6/15/11
TECP I.5 / Adapt / Modify interpass cleaning system for inspection application / 100% / 3/15/11
Deliverables / 1.  Manipulator system able to meet standard UT positioning requirements
2.  Surface cleaning system integrated in system / 100% / 6/15/11
TECP Objective 2: Modify system to reconfigure for various structures.
TECP II.1 / Determine mobility needed for typical structures / 100% / 11/15/10
TECP II.2 / Modify existing MRWS chassis to meet mobility requirements / 100% / 11/15/10
TECP II.3 / Incorporate chassis control in operator interface / 100% / 11/15/10
Deliverables / 1.  Modified MRWS system with adaptive chassis
2.  Test system on representative structres / 100% / 3/15/10
TECP Objective III: Integrate data collection into the operator control system
TECP III.1 / Define HMI requirements / 100% / 3/15/11
TECP III.2 / Modify existing MRWS controller to integrate inspection feedback / 100% / 3/15/11
Deliverables / Operator control pendant designed for inspection operations / 100% / 8/15/11
TECP Objective IV: Provide feature feedback to operator in real-time
TECP IV.1 / Implement filtering algorithm to operate in real-time for inspection data / 100% / 6/15/11
TECP IV.2 / Provide inspection results to operator during the inspection process / 100% / 8/15/11
TECP IV.3 / Add on-board mechanism for in-situ location marking / 100% / 8/1/11
Deliverables / 1.  Onboard data filtering algorithm
2.  Onboard system capable of marking specific location on a structure / 100% / 8/15/11
TECP Objective V: Integrate Objectives I-IV into field-ready inspection platform
TECP V.1 / Fabricate Inspection platform based on work from objectives 1-4 / 100% / 10/15/11
TECP V.2 / Test system and modify as needed / 100% / 10/15/11
TECP V.3 / Demonstrate system use in field and deliver to Synterprise / 100% / 3/15/11
Deliverable / 1.  Fabricated Inspection System
2.  Demonstration of advanced inspection capability / 100% / 10/15/11