| 1. |
- De Backer, Jeroen, 1987-, et al.
(författare)
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Investigation of path compensation methods for robotic friction stir welding
- 2012
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Ingår i: Industrial robot. - : Emerald Group Publishing Limited. - 0143-991X .- 1758-5791. ; 39:6, s. 601-608
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Tidskriftsartikel (refereegranskat)abstract
- Purpose – Friction stir welding (FSW) is a novel method for joining materials without using consumables and without melting the materials. The purpose of this paper is to present the state of the art in robotic FSW and outline important steps for its implementation in industry and specifically the automotive industry.Design/methodology/approach – This study focuses on the robot deflections during FSW, by relating process forces to the deviations from the programmed robot path and to the strength of the obtained joint. A robot adapted for the FSW process has been used in the experimental study. Two sensor-based methods are implemented to determine path deviations during test runs and the resulting welds were examined with respect to tensile strength and path deviation.Findings – It can be concluded that deflections must be compensated for in high strengths alloys. Several strategies can be applied including online sensing or compensation of the deflection in the robot program. The welding process was proven to be insensitive for small deviations and the presented path compensation methods are sufficient to obtain a strong and defect-free welding joint.Originality/value – This paper demonstrates the effect of FSW process forces on the robot, which is not found in literature. This is expected to contribute to the use of robots for FSW. The experiments were performed in a demonstrator facility which clearly showed the possibility of applying robotic FSW as a flexible industrial manufacturing process.
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| 2. |
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| 3. |
- Petterson, Anders, et al.
(författare)
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A Bernoulli principle gripper for handling of planar and 3D (food) products
- 2010
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Ingår i: Industrial robot. - : Emerald. - 0143-991X .- 1758-5791. ; 37:6, s. 518-526
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Purpose - The purpose of this paper is the increase the flexibility of robots used for handling of 3D (food) objects handling by the development and evaluation of a novel 3D Bernoulli gripper. Design/methodology/approach - A new gripper technology have been designed and evaluated. A deformable surface have been used to enable individual product handling. The lift force generated and the force exerted on the product during gripping is measured using a material tester instrument. Various products are tested with the gripper. A experimental/theoretical approach is used to explain the results. Findings - A deformable surface can be used to generate a lift force using the Bernoulli principle on 3D objects. Using a small forming a significant increase in the lift force generated is recorded. Increasing the forming further was shown to have little or even negative effects. The forces exerted on the product during forming was measured to be sufficiently low to avoid product damage. Research limitations/implications - To be able to improve the grippers lift strength a better model and understanding of the flow is needed. Originality/value - A novel Bernoulli gripper for 3D Bernoulli gripping have been designed and evaluated. The gripper enables flexible and delicate handling of various product shapes, 3D as well as 2D. Increased utilization of robots in the food industry can be gained. © Emerald Group Publishing Limited [ISSN 0143-991X].
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| 4. |
- De Backer, Jeroen, 1987-, et al.
(författare)
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Deflection model for robotic friction stir welding
- 2014
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Ingår i: Industrial robot. - Bingley : Emerald Group Publishing Limited. - 0143-991X .- 1758-5791. ; 41:4, s. 365-372
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Tidskriftsartikel (refereegranskat)abstract
- This paper aims to present a deflection model to improve positional accuracy of industrial robots. Earlier studies have demonstrated the lack of accuracy of heavy-duty robots when exposed to high external forces. One application where the robot is pushed to its limits in terms of forces is friction stir welding (FSW). This process requires the robot to deliver forces of several kilonewtons causing deflections in the robot joints. Especially for robots with serial kinematics, these deflections will result in significant tool deviations, leading to inferior weld quality.This paper presents a kinematic deflection model, assuming a rigid link and flexible joint serial kinematics robot. As robotic FSW is a process which involves high external loads and a constant welding speed of usually below 50 mm/s, many of the dynamic effects are negligible. The model uses force feedback from a force sensor, embedded on the robot, and predicts the tool deviation, based on the measured external forces. The deviation is fed back to the robot controller and used for online path compensation.The model is verified by subjecting an FSW tool to an external load and moving it along a path, with and without deviation compensation. The measured tool deviation with compensation was within the allowable tolerance for FSW.The model can be applied to other robots with a force sensor.The presented deflection model is based on force feedback and can predict and compensate tool deviations online.
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| 5. |
- Grahn, Sten, et al.
(författare)
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Spring-assisted gantry robots versus conventional gantry robots: spring constant optimization and work minimization
- 2002
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Ingår i: Industrial robot. - : Emerald. - 0143-991X .- 1758-5791. ; 29:1, s. 53-60
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Tidskriftsartikel (refereegranskat)abstract
- The spring-assisted gantry robots, described in this paper, were designed primarily for the rapid transfer of lightweight objects from one point to another, e.g. to pick objects from a conveyor belt and to place them in a box. The average amount of work required for pick-and-place operations carried out by a conventional gantry robot was decided. Springs were added to conserve the kinetic energy of the main bar, which slides in the X-direction and the work of the same pick-and-place operation was decided. A theoretical study showed that when the spring constant was optimized the required motor work of the spring-assisted robots were 42-95 percent less than the required work of the conventional robot. The conceptual robot exists in mathematical models in Matlab and SIMULINK.
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| 6. |
- Hellström, Thomas, et al.
(författare)
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A software framework for agricultural and forestry robots
- 2013
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Ingår i: Industrial robot. - : Emerald Group Publishing Limited. - 0143-991X .- 1758-5791. ; 40:1, s. 20-26
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this paper is to describe a generic software framework for development of agricultural and forestry robots. The primary goal is to provide generic high-level functionality and to encourage distributed and structured programming, thus leading to faster and simplified development of robots. A secondary goal is to investigate the value of several architecture views when describing different software aspects of a robotics system.Design/methodology/approach: The framework is constructed with a hybrid robot architecture, with a static state machine that implements a flow diagram describing each specific robot. Furthermore, generic modules for GUI, resource management, performance monitoring, and error handling are included. The framework is described with logical, development, process, and physical architecture views.Findings: The multiple architecture views provide complementary information that is valuable both during and after the design phase. The framework has been shown to be efficient and time saving when integrating work by several partners in several robotics projects. Although the framework is guided by the specific needs of harvesting agricultural robots, the result is believed to be of general value for development also of other types of robots.Originality/value: In this paper, the authors present a novel generic framework for development of agricultural and forestry robots. The robot architecture uses a state machine as replacement for the planner commonly found in other hybrid architectures. The framework is described with multiple architecture views.
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| 7. |
- Larsson, Johan, et al.
(författare)
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Laser-based corridor detection for reactive navigation
- 2008
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Ingår i: Industrial robot. - : Emerald. - 0143-991X .- 1758-5791. ; 35:1, s. 69-79
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Tidskriftsartikel (refereegranskat)abstract
- For mobile robots operating in real-world environments, reactive navigation is a useful complement (or even replacement) to pure plan-based metric navigation. Reactive navigation is performed with respect to local perceived features, rather than a global metric reference frame, and can provide reduced installation costs, increased flexibility, and robustness to changes in the environment. To be effective, however, reactive navigation requires fast and reliable perception of the relevant features in the environment. Corridor-like structures are one of the most common features that are used for this purpose. In this paper, we propose a new method for corridor detection from laser data, based on the Hough transform, which is fast, reliable, and noise tolerant. We describe the algorithm, report an extensive experimental evaluation of its performance, and motivate the research with a real application involving the autonomous operation of a loader vehicle in an underground mine.
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| 8. |
- Tegin, Johan, et al.
(författare)
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Tactile sensing in intelligent robotic manipulation - a review
- 2005
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Ingår i: Industrial robot. - : Emerald. - 0143-991X .- 1758-5791. ; 32:1, s. 64-70
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - When designing hardware and algorithms for robotic manipulation and grasping, sensory information is typically needed to control the grasping process. This paper presents an overview of the major grasping and manipulation approaches and the more common hardware used to obtain the necessary sensory information. Design/methodology/approach - This paper presents an overview of tactile sensing in intelligent robotic manipulation. The history the common issues, and applications are reviewed. Sensor performance is briefly discussed and compared to the human tactile sense. Advantages and disadvantages of the most common sensor approaches are discussed. Some examples are given of sensors that are widely available as of today. Eventually, some examples of the state-of-the-art in tactile sensing application are presented. Findings - Although many sensor technologies and strong theoretical models have been developed, there is still much left to be done in intelligent grasping and manipulation. This is partly due to the youth of the field and the complex nature of safe control in uncertain environments. Even though there are impressive results when it comes to specific examples of advanced manipulation, there seems to be room for great improvements of hardware and especially algorithms when it comes to more generic everyday domestic tasks. Originality/value - This paper presents a review of sensor hardware while also giving a glimpse of the major topics in grasping and manipulation. While better hardware of course is desirable, the major challenges seem to lie in the development and application of grasping and manipulation algorithms.
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| 9. |
- Virk, Gurvinder S.
(författare)
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Robot ethics
- 2012
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Ingår i: Industrial robot. - 0143-991X .- 1758-5791. ; 39:3, s. 224-225
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Yang, Wei, et al.
(författare)
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Hybrid oscillator-based no-delay hip exoskeleton control for free walking assistance
- 2021
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Ingår i: Industrial robot. - : Emerald. - 0143-991X .- 1758-5791. ; 48:6, s. 906-914
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Tidskriftsartikel (refereegranskat)abstract
- PurposeWalking-aid exoskeletons can assist and protect effectively the group with lower limb muscle strength decline, workers, first respondersand military personnel. However, there is almost no united control strategy that can effectively assist daily walking. This paper aims to propose ahybrid oscillators’ (HOs) model to adapt to irregular gait (IG) patterns (frequent alternation between walking and standing or rapid changing ofwalking speed, etc.) and generate compliant and no-delay assistive torque.Design/methodology/approachThe proposed algorithm, HOs, combines adaptive oscillators (AOs) with phase oscillator through switchingassistive mode depending on whether or not the AOs' predicting error of hip joint degree is exceeded our expectation. HOs can compensate fordelay by predicting gait phase when in AOs mode. Several treadmill and free walking experiments are designed to test the adaptability andeffectiveness of HOs model under IG.FindingsThe experimental results show that the assistive strategy based on the HOs is effective under IG patterns, and delay is compensatedtotally under quasiperiodic gait conditions where a smoother human–robot interaction (HRI) force and the reduction of HRI force peak are observed.Delay compensation is found very effective at improving the performance of the assistive exoskeleton.Originality/valueA novel algorithm is proposed to improve the adaptability of a walking assist hip exoskeleton in daily walking as well asgenerate compliant, no-delay assistive torque when converging.
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