Thomas Lehmann

Design and development of a magnetic ROV for coating inspection

Project Dates: April 2022 - present

Company/organization: Confined Space Robotics (CSR)

Highlights:

• Remotely Operated Vehicle (ROV) designed for remote visual and Dry Film Thickness (DFT) inspection of coatings
• Equipped with magnetic wheels (permanent magnets) for crawling vertical and upside down ferromagnetic surfaces
• Visual inspection is facilitated via a pan-tilt-zoom (PTZ) camera (in-house developed pan-tilt mechanism)
• Coating thickness inspection is facilitated via a deployable DFT measurement probe
• Web-based and device-agnostic user interface (UI) for ROV control

Roles and responsibilities:

• Software lead: Design, development and implementation of the ROS-based software stack from backend (e.g., hardware drivers & interfacing) to behavioral and operational logic to frontend (device-agnostic web-based UI)
• Involvement in all aspects of prototyping and product development
• Hardware integration and driver design and implementation
• Mechanical design of the ROV's chassis, the inspection tool deployment systems, and the PTZ camera
• Electronics and network/communication infrastructure design (ROV-internal and operator-facing devices)
• Assembly, testing and quality control

Being a lead developer and therefore heavily involved in this project was and continues to be a very rewarding and interesting experience. I gained a lot of additional experience in robotics software design, and mechanical and electrical design. I also gained new experience in product development and design, and the many intricacies involved in creating a viable and user-friendly product while at the same time keeping manufacturing and cost constraints in mind.

This project also gave me the opportunity to directly apply my expertise in robotics software design and development gained during work on previous projects, which helped accelerate the development of the system.

Design and Development of a ROS-based Software Stack for Robotic Additive Manufacturing

Project Dates: October 2018 - March 2022

Company/organization: Additive Design and Manufacturing Systems (ADaMS) Lab and InnoTech Alberta

Highlights:

• Ability to take trajectories generated via Mastercam-Aplus (planar and multi-axis builds) and Cura (planar builds, re-configured to work for WAAM)
• Ability to interpret RepRap (planar) and Mastercam-Aplus (planar and multi-axis) gcodes
• Ability to interface and control various types of robot arms and cartesian robots (e.g., 3 or 5-axis CNC systems)
• Ability to incorporate sensing systems for sensor fusion, machine learning and control feedback
• Includes digital twins
• Where other softwares provide only open-loop trajectory execution (Robotmaster, Octopuz), this software has the potential ability to execute builds with closed-loop real-time process control

Roles and responsibilities:

• Software lead: Design, development and implementation of the robotic AM software stack from backend (interfacing robots, depositions systems and sensors) to execution logic to UI and trajectory generation and inputs.
• Hardware integration and driver development
• Hiring and supervision of senior undergraduate students assisting with software implementation
• Supervision and management of software implementation, code review and approval using the Pull Request Workflow

When I first joined the ADaMS lab at the University of Alberta, I began to explore how to execute 3D printing trajectories on industrial manipulators using ROS. With my prior experience with ROS-Industrial-based robot drivers, the kinematics framework MoveIt! and hardware integration via ROS, I was confident that it was possible to develop a software for execution of 3D printing trajectories using software frameworks I was already familiar with from past projects. This initial idea developed into a functional and hardware-agnostic AM software stack for the execution of planar and multi-axis AM trajectories with successful builds of demo components.

The stack has so far been successfully used on different Motoman robot models (MA2010 and SIA5) and a custom, in-house built CNC-based (GRBL) 3-axis cartesian gantry system (see above videos). Initial hardware simulation tests (ABB's RobotStudio) have shown that it is possible to execute the same trajectories on ABB robots, with no modification to the stack. Only a hardware-specific driver is needed. One of the most attractive features of the stack is the hardware-agnostic and modular design that enables the quick integration of different deposition and robotic systems and extension with algorithms for the real-time monitoring and control of the deposition process. A special thank you goes to the students who helped with integration and development of software drivers for some systems. For robotics-centred data structure definitions and trajectory visualization, the stack uses a modified version of the ROS Additive Manufacturing stack.

Development of a robotic solution for coating of tanks

Project dates: April 2022 - Present

Company/organization: Confined Space Robotics

Highlights:

• Automatic coating of a vessel interior (e.g., tank) without requiring human confined space entry
• Minimization of coating thickness variation through the use of a robot arm
• Customized, asynchronous spray on/off timing to minimize coating accumulation during deceleration at the end of a coating path

Roles and responsibilities:

• Development of UR pendant programs using RoboDK for execution of collision free coating trajectories
• Development and implementation of application-specific software plugins, post processors for Universal Robots
• Development and implementation of a custom URScript post processor for asynchronous and accurate spray gun on/off timing

This project was interesting to work on because it gave me the opportunity to work with and gain detailed experience with the powerful offline robot programming software RoboDK. Especially getting to know the API and post processor implementation gave me valuable insight.

Commissioning of an industrial robotic Wire and Arc Additive Manufacturing (WAAM) cell

Project Dates: November 2018 - March 2019

Company/organization: InnoTech Alberta

Highlights:

• 8-axis industrial robotic welding cell with 2-axis, 550 kg workpiece positioner and 6-axis robot arm
• Integrated Fronius TPS 5000 CMT welding power supply

Roles and responsibilities:

Led and coordinated the commissioning of the cell:

• Responsible for the final design of the robotic cell layout including custom robot-welder integration and placement in the lab space
• Coordinated the system requirements, cell layout and integration of welding system with Yaskawa Motoman
• Coordinated the shipping and receiving of the cell components
• Coordinated and lead the preparation of the lab space, electrical installations and mechanical assessments
• Coordinated and lead the system installation (electrical and mechanical)