Enhancing Payload Capacity with Dual-Arm Manipulation and Adaptable Mechanical Intelligence

2020 ◽  
pp. 1-15
Author(s):  
Raymond Kim ◽  
Stephen Balakirsky ◽  
Konrad Ahlin ◽  
Matthew Marcum ◽  
Anirban Mazumdar
Keyword(s):  
Cooperative Control ◽  
Load Capacity ◽  
Load Sharing ◽  
Total Load ◽  
Overall Design ◽  
Fundamental Limit ◽  
Physical Experiments ◽  
Payload Capacity ◽  
Dual Arm ◽  
Pneumatic Tool

Abstract Individual manipulators are limited by their vertical total load capacity. This places a fundamental limit on the weight of loads that a single manipulator can move. Cooperative manipulation with two arms has the potential to increase the net weight capacity of the overall system. However, it is critical that proper load sharing takes place between the two arms. In this work, we outline a method that utilizes mechanical intelligence in the form of a whiffletree. This system enables load sharing that is robust to position deviations between the two arms. The whiffletree utilizes pneumatic tool-changers which enable autonomous attachment/detachment. We outline the overall design of a whiffletree for dual-arm manipulation. We also illustrate how this type of mechanical intelligence can greatly simplify cooperative control. Lastly, we use physical experiments to illustrate enhanced load capacity. Specifically, we show how two UR5 manipulators can re-position a 7kg load. This load would exceed the weight capacity of a single arm, and we show that the average forces on each arm remains below this level and are relatively evenly distributed.

scholarly journals Cooperative Control Experiments of a 3D Dual-Arm Flexible Manipulator.

2000 ◽  
Vol 66 (649) ◽  
pp. 3063-3068
Author(s):  
Mitsuhiro YAMANO ◽  
Jin-Soo KIM ◽  
Atsushi KONNO ◽  
Masaru UCHIYAMA
Keyword(s):  
Cooperative Control ◽  
Flexible Manipulator ◽  
Dual Arm

scholarly journals Numerical modelling of perimeter pile groups in clay

2013 ◽  
Vol 50 (3) ◽  
pp. 250-258 ◽  
Author(s):  
A.V. Rose ◽  
R.N. Taylor ◽  
M.H. El Naggar
Keyword(s):  
Load Distribution ◽  
Load Capacity ◽  
Relative Effectiveness ◽  
Pile Group ◽  
Block Type ◽  
Pile Groups ◽  
Total Load ◽  
Group Behaviour ◽  
Pile Interaction ◽  
Spacing Length

The load distribution among piles in a group varies such that the inner piles often carry a smaller share of the total load compared to the outer piles, which is a result of increased soil–pile interaction. The main objective of this paper is to establish the relative effectiveness of pile groups with no inner piles (perimeter group), when compared to the more common grid configuration. The numerical investigation utilized the finite element programme ABAQUS and considered a range of variables that affect pile group behaviour including number of piles, pile spacing, length/diameter ratio, and soil strength. It was demonstrated that a complete grid group is less efficient than a perimeter group, where efficiency is defined as the load capacity of the whole group expressed as a ratio of the number of piles in the group multiplied by the load capacity of a single isolated pile. Efficiencies close to unity were observed for some perimeter groups. Perimeter groups also showed that a “block” type group failure could occur, where piles were placed at a spacing of less than 2.0 pile diameters,d, centre-to-centre. This often, but not always, led to a reduction in the efficiency of the pile group.

Skillful Operating of Working Plate to Control Ball Rolling Motion With a Dual Arm Robot

2013 ◽  
Author(s):  
Shun Kinoshita ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Wei Wu
Keyword(s):  
Cooperative Control ◽  
Present Report ◽  
Past Research ◽  
Circular Path ◽  
Rotary Axes ◽  
Ball Rolling ◽  
Novel Method ◽  
Rotational Motions ◽  
Dual Arm Robot ◽  
Dual Arm

Industrial dual-arm robots have been gaining attention as novel tools in the field of new automation. Our past research has focused on using them flexibly to control both the linear and rotational motions of a working plate. However, it has been difficult to measure the synchronous accuracy of two rotary axes without a high-accuracy gyro sensor. We therefore developed a novel method to measure the synchronous accuracy of the two rotary axes of a working plate with a ball, in which the ball is kept rolling around a circular path by dual-arm cooperative control. In the present report, in order to widen the range of application, we tried to keep the ball rolling around a rhomboid path, which is one of the polygonal paths used on a working plate by dual-arm cooperative control. It could be seen that there is some possibility of generating an equal speed diamond motion by inputting wave as the odd power of a trigonometric function and considered a deceleration angle with the robot that we handled.

The Effect of a Fatigue Failure on the Wellhead Ultimate Load Capacity

2012 ◽  
Author(s):  
Lorents Reinås ◽  
Morten Sæther ◽  
Bernt Sigve Aadnøy
Keyword(s):  
Fatigue Fracture ◽  
Fatigue Failure ◽  
North Sea ◽  
Ultimate Load ◽  
Load Capacity ◽  
Load Sharing ◽  
External Loading ◽  
Structural Members ◽  
Ultimate Load Capacity ◽  
Load Bearing

A subsea well will experience external loading during drilling operations that can lead to the development of a fatigue fracture in the primary load bearing structural members of the upper well construction. Such a fatigue fracture can occur at several fatigue hotspots which all are located in the upper part of a subsea well. There are two main load sharing structural members; the outer tubular string named the conductor (structural) casing and the next tubular string named the surface casing. Both these strings have a circumferential load bearing weld close to the top. The load sharing between these 2 tubular strings are affected by the supported weight from further tubular strings placed inside the well. This paper discusses the residual ultimate load capacity of a typical North Sea subsea well assuming that a fatigue fracture has developed. The discussion is based on FEM analysis results where a fully developed fatigue fracture has been introduced to the analytical model of a typical well either to the conductor part of the well or to the surface casing string. Then the residual ultimate load capacity is evaluated assuming a fully developed fatigue fracture. Evaluations presented herein can be important and necessary tools in considering the consequences of a possible fatigue failure of a subsea well. A reduction in ultimate load capacity due to a fatigue fracture may reduce the safety margin should an accidental or extreme loading occur. The results indicate that the location of the potential fatigue failure is important when assessing the residual ultimate load capacity. If the factored fatigue life of a subsea well is approaching its limit the presence of a fatigue fracture should be assumed. The most prudent approach would then be to perform a permanent P&A operation of the well. Planning of such operations should comprehend the possibility of reduced structural capacity of the well due to a fatigue fracture. This paper also discusses the results in an operational context. The applied methodology is outlined and illustrative results are presented from a typical North Sea well.

Cooperative control of dual-arm robots in different human-robot collaborative tasks

2019 ◽  
Vol 40 (1) ◽  
pp. 95-104 ◽  
Author(s):  
Xinbo Yu ◽  
Shuang Zhang ◽  
Liang Sun ◽  
Yu Wang ◽  
Chengqian Xue ◽  
...  
Keyword(s):  
Cooperative Control ◽  
Force Feedback ◽  
Control Strategies ◽  
Experimental Results ◽  
Distant Object ◽  
Content Type ◽  
Human Arm ◽  
Dual Arm Robot ◽  
Dual Arm ◽  
Robot Platform

Purpose This paper aims to propose cooperative control strategies for dual-arm robots in different human–robot collaborative tasks in assembly processes. The authors set three different regions where robot performs different collaborative ways: “teleoperate” region, “co-carry” region and “assembly” region. Human holds the “master” arm of dual-arm robot to operate the other “follower” arm by our proposed controller in “teleoperation” region. Limited by the human arm length, “follower” arm is teleoperated by human to carry the distant object. In the “co-carry” region, “master” arm and “follower” arm cooperatively carry the object to the region close to the human. In “assembly” region, “follower” arm is used for fixing the object and “master” arm coupled with human is used for assembly. Design/methodology/approach A human moving target estimated method is proposed for decreasing efforts for human to move “master” arm, radial basis functions neural networks are used to compensate for uncertainties in dynamics of both arms. Force feedback is designed in “master” arm controller for human to perceive the movement of “follower” arm. Experimental results on Baxter robot platform show the effectiveness of this proposed method. Findings Experimental results on Baxter robot platform show the effectiveness of our proposed methods. Different human-robot collaborative tasks in assembly processes are performed successfully under our cooperative control strategies for dual-arm robots. Originality/value In this paper, cooperative control strategies for dual-arm robots have been proposed in different human–robot collaborative tasks in assembly processes. Three different regions where robot performs different collaborative ways are set: “teleoperation” region, “co-carry” region and “assembly” region.

Behaviour of Vertically Loaded Piled Raft System

2020 ◽  
Vol 17 (5) ◽  
pp. 2383-2387
Author(s):  
K. Merin Jose ◽  
Divya Krishnan ◽  
P. T. Ravichandran
Keyword(s):  
Bearing Capacity ◽  
Load Capacity ◽  
Load Test ◽  
Ultimate Load Capacity ◽  
Foundation Soil ◽  
Total Load ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Dense State

A foundation gives the overall strength to a building by providing a level surface for the building to stand and distributing the total load uniformly to the underlying soil. The type of foundation to be chosen varies with the foundation soil and site conditions. Piled raft system are a type of foundation preferred when the bearing strata has less soil bearing capacity and a huge load has to be transferred. Thus Piled raft foundation is a foundation system which uses the combined effects of both rafts and piles such that it is expected to transfer huge loads without large settlement. An ample evaluation of factors like number of piles, length of piles, and degree of compaction of soil that affects the performance of the foundation is required, to understand the concept of piled raft foundation. This study was based on the behaviour of vertically loaded piled raft system by varying the length of pile as 100 mm, 150 mm and 200 mm with 4 and 9 numbers of pile conducted on loose and dense state in cohesion less soil. A vertical load test was conducted on unpiled raft both in loose and dense state of soil also and the results obtained from both piled and unpiled rafts were compared together. The compared results indicated an improvement in ultimate load capacity and settlement reduction. A settlement reduction of 32.71% and increased bearing capacity of 63.67% were observed when compared to unpiled raft under dense condition. About 84% of increase in bearing capacity of the piled raft system was observed with varying the degree of compaction of soil from loose to dense state of soil. An optimum design of this piled raft foundation can provide an alternative foundation for high rise buildings, transmission towers, bridges etc. and it can provide an aid to the threat of differential settlement for heavy loaded buildings in poor bearing strata.

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