Survey on human–robot collaboration in industrial settings: Safety, intuitive interfaces and applications

The Kutzbach-Grubler mobility criterion calculates the degrees of freedom of a general mechanism. However, the criterion can break down for mechanisms with special geometries, and in particular, the class of so-called overconstrained parallel mechanisms. The problem is that the criterion treats all constraints as active, even redundant constraints, which do not affect the mechanism degrees of freedom. In this paper we reveal a number of screw systems of a parallel mechanism, explore their inter-relationship and develop an original theoretical framework to relate these screw systems to motion and constraints of a parallel mechanism to identify the platform constraints, mechanism constraints and redundant constraints. The screw system characteristics and relationships are investigated for physical properties and a new approach to mobility analysis is proposed based on decompositions of motion and constraint screw systems. New versions of the mobility criterion are thus presented to eliminate the redundant constraints and accurately predict the platform degrees of freedom. Several examples of overconstrained mechanisms from the literature illustrate the results.

Mobility of Overconstrained Parallel Mechanisms

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Using Algebraic Geometry

Currently, a large number of industrial robots have been deployed to replace or assist humans to perform various repetitive and dangerous manufacturing tasks. However, based on current technologica...

Human–robot interaction in industrial collaborative robotics: a literature review of the decade 2008–2017

A method to learn and reproduce robot force interactions in a human–robot interaction setting is proposed. The method allows a robotic manipulator to learn to perform tasks that require exerting forces on external objects by interacting with a human operator in an unstructured environment. This is achieved by learning two aspects of a task: positional and force profiles. The positional profile is obtained from task demonstrations via kinesthetic teaching. The force profile is obtained from additional demonstrations via a haptic device. A human teacher uses the haptic device to input the desired forces that the robot should exert on external objects during the task execution. The two profiles are encoded as a mixture of dynamical systems, which is used to reproduce the task satisfying both the positional and force profiles. An active control strategy based on task-space control with variable stiffness is then proposed to reproduce the skill. The method is demonstrated with two experiments in which the robot learns an ironing task and a door-opening task.

Imitation Learning of Positional and Force Skills Demonstrated

This work deals with deep and ultra-deep waters installation by the so-called “J-Lay” method, which consists in laying submarine pipelines with a straight stinger at near-vertical angles. A hierarchy of simple analytical models is proposed starting from the classical catenary and enriching it to overcome its drawbacks. A novel approach for detecting the boundary layer phenomenon is proposed, and constitutes the base of two of the developed models. All models are compared with each other and with the results of refined numerical simulations in a case of practical interest. In the considered examples the stiffness of the soil has scarce influence, while the boundary layer phenomenon is very important and detected correctly, both from a qualitative and quantitative point of view, by the second class of proposed models.

Simple analytical models for the J-lay problem

A new class of reconfigurable parallel kinematic machines

Purpose – This paper aims to deal with the problem of programming robots in industrial contexts, where the need of easy programming is increasing, while robustness and safety remain fundamental aspects. Design/methodology/approach – A novel approach of robot programming can be identified with the manual guidance that permits to the operator to freely move the robot through its task; the task can then be taught using Programming by Demonstration methods or simple reproduction. Findings – In this work, the different ways to achieve manual guidance are discussed and an implementation using a force/torque sensor is provided. Experimental results and a use case are also presented. Practical implications – The use case shows how this methodology can be used with an industrial robot. An implementation in industrial contexts should be adjusted accordingly to ISO safety standards as described in the paper. Originality/value – This paper presents a complete state-of-the-art of the problem and shows a real practical...

Manual guidance for industrial robot programming

Dynamics modelling and control of the 3-RCC translational platform

A new three-d.o.f. parallel mechanism, with 3-RPC topology, is presented in the paper and its kinematics is studied. The proposed architecture, if proper geometrical conditions are satisfied, has an overconstrained structure which allows motions of pure translation. The simple structure of the mechanism allows finding closed-form solutions for both inverse and direct position kinematics; the differential analysis has been developed as well. by deriving a symbolic expression for the Jacobian matrix. Then, some design considerations are exposed to keep the singular points out of the working space of the mechanism and all the isotropic configurations are eventually identified.

Massimo Callegari

Papers

Simple analytical models for the J-lay problem

A new class of reconfigurable parallel kinematic machines

Manual guidance for industrial robot programming

Dynamics modelling and control of the 3-RCC translational platform

Kinematic Analysis of a Novel Translational Platform