Skill Assistance with Robot for Manual Welding


by Mustafa Suphi Erden

Marie Curie Intra-European Fellowship, Project No: 297857



Host Institute:

Learning Algorithms and Systems Laboratory (LASA), École Polytechnique Fédérale de Lausanne






















































Work Performed

The following items of work were performed within the project period:

  1. An interactive and shared controlled robotic welding/painting setup was developed using the KUKA LWR 4+ robot, where the system could introduce force disturbances for impedance measurement purposes during welding/painting.
  2. Impedance measurements were performed and directional damping type robotic assistance was implemented with subjects while they were doing airbrush painting with the interactive system with their dominant and non-dominant hands (Fig. 1a). Dominant and non-dominant hand paintings corresponded respectively to skilled and unskilled manipulations and served as a preliminary test case prior to the welding experiments with professional and novice welders.
  3. Impedance measurements were performed with professional and novice welders when they were doing TIG welding interactively with the robot (Fig. 1b).
  4. (a)(b)

    Fig. 1: (a) Airbrush painting interactively with KUKA LWR. (b) TIG welding interactively with KUKA LWR.

  5. An impedance compensation type robotic assistance was developed for manual welding by using the knowledge of hand-impedance characteristics of professional and novice welders. The assistive scheme (Fig. 2) estimates the intended welding direction in real-time using a smooth Kalman filter and compensates the inferior level of hand-impedance of the novice welders in the perpendicular directions. The scheme was applied and tested by professional and novice welders. The assistive scheme was applied also for airbrush painting with dominant and non-dominant hands.
  6. Fig. 2: Impedance compensation type robotic assistance integrated with the admittance control of the robot. [Parameters: fh: human force; mt: mass of the torch; ft: inertial force of the torch; fs: force sensor reading; fc: commanded force; mv: virtual mass at the end effector; pd: desired position command; s: Laplace derivator; vd: desired velocity command; pr: actual robot position; M: compensated mass; D: compensated damping; K: compensated stiffness; fv: compensation force; fa: actual assistive force.]

  7. A training system was developed for manual welding by integrating a LED and a buzzer to the welding helmet (Fig. 3). The training setup estimates the intended welding direction, detects the deviations from the estimated direction due to hand tremor, and generates visual or audio alarms as feedback to notice the welder. The training system was applied and tested by professional and novice welders.
  8. Fig. 3: The helmet is equipped with a LED and a buzzer in order to give alarms in the form of a flashing light and beep sound for training.