Sensor integration for robotic laser welding processes

Abstract

The use of robotic laser welding is increasing among industrial applications, because of its ability to weld objects in three dimensions. Robotic laser welding involves three sub-processes: seam detection and tracking, welding process control, and weld seam inspection. Usually, for each sub-process, a separate sensory system is required. The use of separate sensory systems leads to heavy and bulky tools, in contrast to compact and light sensory systems that are needed to reach sufficient accuracy and accessibility. In the solution presented in this paper all three subprocesses are integrated in one compact multipurpose welding head. This multipurpose tool is under development and consists of a laser welding head, with integrated sensors for seam detection and inspection, while also carrying interfaces for process control. It can provide the relative position of the tool and the work piece in three-dimensional space. Additionally, it can cope with the occurrence of sharp corners along a three-dimensional weld path, which are difficult to detect and weld with conventional equipment due to measurement errors and robot dynamics. In this paper the process of seam detection will be mainly elaborated.

Reconfigurable 3D Laser-Stripe Sensor for Welding Processes

“…In [3] and [4], laser-stripe sensors are developed. In [5], three laser-stripes are used to detect the seam more effectively. For the welding purpose, there are several commercial devices [6].…”

An efficient system based on model segmentation for weld seam grinding robot

“…Laser structured light is usually used to extract and track the weld contour in the form of laser emitter and monocular camera. There are a variety of shapes of the laser stripe, including linear [23], multi-linear [24], a cross [25], a triangle [26], etc. SHAO [24] designed three different wavelengths of laser to measure the seam width, seam center, and the normal vector of the weld face, and the result of experiment revealed that the proposed method could meet the precision demand of space narrow butt joint.…”