Process Qualification for a Mobile Robotic Welding System Through Manipulability

Author(s):  
Justin Stacy ◽  
Daniel Langley ◽  
Stephen L. Canfield

Advances in mobile robotics make these systems viable alternatives for developing new methods and techniques for manufacturing processes such as welding. When considering welding as a manufacturing process, the ability of the equipment to conduct the weld process must be verified. This step is called weld process validation and is generally conducted when a new machine or technique is introduced to the weld process. Traditionally, the weld validation process has focused on the electro-thermal aspects of the weld process, while the (human) welder qualification provides a certification step to ensure that an operator can perform the motion-control aspects of the weld operation while welding. The lack of industry standards for mechanized welding makes it difficult to introduce mobile robotic welding systems with validated performance in the market place. This paper will propose one approach to consider the motion control portion of the weld process validation for welding systems based on mobile robotic platforms. In particular, this paper will consider a skid-steer type mobile robot that is able to weld in flat, horizontal and vertical orientations. The paper will consider the motion-control portion of the weld validation process and will suggest a method that compares a mobile-robot-based welding process to a baseline (fixed-base track system) welding process through spanning manipulability ellipses. This approach allows general topologies of a mobile robotic welding system to be considered in a general way as a step to making mobile robotic welding a viable welding process.

Author(s):  
Stephen L. Canfield ◽  
Josh Qualls ◽  
Alexander Shibakov

As mobile robotic systems advance, they become viable technologies for automating manufacturing processes in fields that traditionally have not seen much automation. Such fields include shipbuilding, windmill, tank, and pipeline construction. Some of the manufacturing tasks in these fields require process validation prior to use in the manufacturing process. One such example process is welding. However, there is a lack of industry standards for mechanized or robotic welding that can impede the introduction of mobile robotic welding systems in the market place. There is also a lack of generalized fitness measures that gauge the suitability of mobile robot topologies or dimensional designs to a set of tasks and can be used in the design or verification process. This paper will consider the metrics that can be used in evaluating mobile robot designs for welding tasks based on kinematic and dynamic characteristics. The approach is based on a representation of the weld task and robot capabilities as a pair of n-dimensional subsets in the Euclidean n-space, where the weld task is considered a repetitive pattern constructed along the weld seam and both kinematic and dynamic characteristics are considered for the robot. The motivation is to allow different mobile manipulator designs to be measured using a direct geometric comparison of the capabilities of the robot to the requirements of the task. Three mobile welding platforms having different topological kinematic arrangements and will be evaluated based on this metric. This metric will further be shown to supplement the weld qualification process through verification of the motion control portions of the weld process based on a specific robot design. The method will contribute to the design and development of mobile robotic welding systems to become viable and accepted.


Author(s):  
Stephen L. Canfield ◽  
Daniel Langley ◽  
Alexander Shibakov

Developments in mobile robotic systems are leading to new methods and techniques for manufacturing processes in fields that traditionally have not seen much automation. Some of these tasks require process validation prior to use in the manufacturing process. One such example process is welding. However, there is a lack of industry standards for mechanized or robotic welding that can impede the introduction of mobile robotic welding systems in the market place. There is also a lack of generalized fitness measures that gauge the suitability of mobile robot topologies or dimensional designs to a set of tasks and can be used in the design or verification process. This paper will propose such a metric and demonstrate its use in evaluating mobile robot designs for welding tasks. The approach will be based on the representation of a general task as a pair of n-dimensional subsets in the Euclidean n-space. Similarly, the robot capabilities are represented as n-dimensional subsets (manipulability and torque ellipse) in the Euclidean n-space. The motivation is to enable a direct geometric comparison of the capabilities of the robot to the requirements of the task yielding a quantitative measure of fitness. This method is suggested to be well suited to tasks comprised of a relatively short sequence of well-defined motions, called gaits, which are performed repeatedly or in a periodic manner. Some examples are welding, swimming, painting or inspection. The paper will demonstrate the use of this metric in the evaluation and design of mobile robots for welding tasks with a desired set of weld pattern motions. Three mobile welding platforms having different topological kinematic arrangements will be evaluated based on this design verification metric. This metric will further be shown to supplement the weld qualification process through verification of the motion control portions of the weld process based on a specific robot design. The method will contribute to the design and development of mobile robotic welding systems to become viable and accepted manufacturing processes.


2012 ◽  
Vol 538-541 ◽  
pp. 2636-2640
Author(s):  
Shi Zhu Feng ◽  
Ming Xu

Robotics is a spiry integral technology of mechanics, electrics and cybernetics. Through systematical study of a wheeled mobile robot, The kinematic model of it is deduced. A Cerebella Model Articulation Controller (CMAC) PID controller was developed to control the motion to accomplish the realistic motions of the wheeled mobile robot system. The experimental is carried out. The results prove the algorithm is correct, and indicate that the design of CMAC-PID controller is a success. The whole research will provide a reference to the study of the mobile robotics.


2020 ◽  
Vol 8 (5) ◽  
pp. 5246-5251

Customary automated welding, basic in ventures, for example, car creation, gets unfeasible in enterprises that utilization unstructured assembling systems, for example, shipbuilding. This is expected to some extent to the size of the made frameworks and the size and areas of the weld. In these unstructured assembling conditions, the cutting edge for automated welding has generally comprised of a fixed-track framework with a mechanical welding carriage that works along the track. In any case, elective automated welding approaches that utilize advancements from the field of versatile mechanical autonomy are being sought after. One such model is the semiautonomous Versatile Robotic Welding System (MRWS). The MRWS is a lightweight versatile controller comprising of a two-degrees-of-opportunity portable stage and a threedegrees-of-opportunity burn controller. The MRWS is equipped for climbing ferrous surfaces by the utilization of changeless magnet tracks and situating the welding light along a weld joint. This framework is intended to automate the welding procedure for an assortment of weld joints with insignificant arrangement time. Arrangement comprises of putting the MRWS superficially to be welded and heading to the expected weld joint. So as to be used in a producing condition, such a framework must be confirmed for the welding procedure it is performing. This paper exhibits and confirms the MRWS as a legitimate other option for automated welding in unstructured situations. The confirmation procedure comprises of two parts: plan approval dependent on hypothetical investigation of the MRWS framework models to demonstrate the weld procedure necessities can be met, trailed by an exact confirmation dependent on AWS weld test particulars for a particular, normally utilized welding process. The plan approval centers around the two essential contrasts between the MRWS and demonstrated fixed-track motorized welding frameworks, burn movement control on a portable stage, and effect of the MRWS attractive feet on the weld process. The observational confirmation was performed on a vertical section weld on gentle steel with tough movement, 3G-PF


2021 ◽  
Vol 24 (4) ◽  
pp. 195-201
Author(s):  
Dušan Hrubý ◽  
Dušan Marko ◽  
Martin Olejár ◽  
Vladimír Cviklovič ◽  
Dominik Horňák

Abstract The paper deals with comparing electricity power consumption of various control algorithms by simulating differential mobile robot motion control in a vineyard row. In field of autonomous mobile robotics, the quality of control is a crucial aspect. Besides the precision of control, the energy consumption for motion is becoming an increasingly demanding characteristic of a controller due to the increasing costs of fossil fuels and electricity. A simulation model of a differential drive mobile robot motion in a vineyard row was created, including robot dynamics for evaluating motion consumption, and there were implemented commonly used PID, Fuzzy, and LQ control algorithms, the task of which was to navigate the robot through the centre of vineyard row section by measuring distances from trellises on both robot sides. The comparison was carried out using Matlab software and the best results in terms of both power consumption and control accuracy were achieved by LQI controller. The designed model for navigating the robot through the vineyard row centre and optimized controllers were implemented in a real robot and tested under real conditions.


2010 ◽  
Vol 7 ◽  
pp. 109-117
Author(s):  
O.V. Darintsev ◽  
A.B. Migranov ◽  
B.S. Yudintsev

The article deals with the development of a high-speed sensor system for a mobile robot, used in conjunction with an intelligent method of planning trajectories in conditions of high dynamism of the working space.


2016 ◽  
Vol 85 (7) ◽  
pp. 657-662
Author(s):  
Satoshi YAMANE

Author(s):  
Aaron T. O’Toole ◽  
Stephen L. Canfield

Skid steer tracked-based robots are popular due to their mechanical simplicity, zero-turning radius and greater traction. This architecture also has several advantages when employed by mobile platforms designed to climb and navigate ferrous surfaces, such as increased magnet density and low profile (center of gravity). However, creating a kinematic model for localization and motion control of this architecture is complicated due to the fact that tracks necessarily slip and do not roll. Such a model could be based on a heuristic representation, an experimentally-based characterization or a probabilistic form. This paper will extend an experimentally-based kinematic equivalence model to a climbing, track-based robot platform. The model will be adapted to account for the unique mobility characteristics associated with climbing. The accuracy of the model will be evaluated in several representative tasks. Application of this model to a climbing mobile robotic welding system (MRWS) is presented.


Robotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 48
Author(s):  
Mahmood Reza Azizi ◽  
Alireza Rastegarpanah ◽  
Rustam Stolkin

Motion control in dynamic environments is one of the most important problems in using mobile robots in collaboration with humans and other robots. In this paper, the motion control of a four-Mecanum-wheeled omnidirectional mobile robot (OMR) in dynamic environments is studied. The robot’s differential equations of motion are extracted using Kane’s method and converted to discrete state space form. A nonlinear model predictive control (NMPC) strategy is designed based on the derived mathematical model to stabilize the robot in desired positions and orientations. As a main contribution of this work, the velocity obstacles (VO) approach is reformulated to be introduced in the NMPC system to avoid the robot from collision with moving and fixed obstacles online. Considering the robot’s physical restrictions, the parameters and functions used in the designed control system and collision avoidance strategy are determined through stability and performance analysis and some criteria are established for calculating the best values of these parameters. The effectiveness of the proposed controller and collision avoidance strategy is evaluated through a series of computer simulations. The simulation results show that the proposed strategy is efficient in stabilizing the robot in the desired configuration and in avoiding collision with obstacles, even in narrow spaces and with complicated arrangements of obstacles.


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