Extending an industrial root controller : implementation and applications of a fast open sensor interface

An overview is given of the design and implementation of a platform for fast external sensor integration in an industrial robot system called ABB S4CPlus. As an application and motivating example, the implementation of force-controlled grinding and deburring within the AUTOFETT-project is discussed. Experiences from industrial usage of the fully developed prototype confirms the appropriateness of the design choices, thus also confirming the fact that control and software need to be tightly integrated. The new sensor can be used for the prototyping and development of a wide variety of new application

Performance evaluation of parallel manipulators for milling application

This paper focuses on the performance evaluation of the parallel manipulators for milling of composite materials. For this application the most significant performance measurements, which denote the ability of the manipulator for the machining are defined. In this case, optimal synthesis task is solved as a multicriterion optimization problem with respect to the geometric, kinematic, kinetostatic, elastostostatic, dynamic properties. It is shown that stiffness is an important performance factor. Previous models operate with links approximation and calculate stiffness matrix in the neighborhood of initial point. This is a reason why a new way for stiffness matrix calculation is proposed. This method is illustrated in a concrete industrial problem

Technology-assisted training of arm-hand skills in stroke: concepts on reacquisition of motor control and therapist guidelines for rehabilitation technology design

<p>Abstract</p> <p>Background</p> <p>It is the purpose of this article to identify and review criteria that rehabilitation technology should meet in order to offer arm-hand training to stroke patients, based on recent principles of motor learning.</p> <p>Methods</p> <p>A literature search was conducted in PubMed, MEDLINE, CINAHL, and EMBASE (1997–2007).</p> <p>Results</p> <p>One hundred and eighty seven scientific papers/book references were identified as being relevant. Rehabilitation approaches for upper limb training after stroke show to have shifted in the last decade from being analytical towards being focussed on environmentally contextual skill training (task-oriented training). Training programmes for enhancing motor skills use patient and goal-tailored exercise schedules and individual feedback on exercise performance. Therapist criteria for upper limb rehabilitation technology are suggested which are used to evaluate the strengths and weaknesses of a number of current technological systems.</p> <p>Conclusion</p> <p>This review shows that technology for supporting upper limb training after stroke needs to align with the evolution in rehabilitation training approaches of the last decade. A major challenge for related technological developments is to provide engaging patient-tailored task oriented arm-hand training in natural environments with patient-tailored feedback to support (re) learning of motor skills.</p

Experimental verification of friction and dynamic models of a parallel kinematic machine

The Gantry-Tau is a parallel kinematic manipulator (PKM) that overcomes the workspace limitations of typical PKMs, while retaining PKM benefits such as small moving masses and high stiffness. An experimental verification of the dynamics of the Gantry-Tau is presented for the first time in this paper. A new friction model based on axial forces in the links of the 3-DOF Gantry-Tau combined with a recent inverse dynamics model for parallel kinematic machines is also presented and verified experimentally. The inverse dynamics model combining the friction model and the Jacobians shows a good match to the measured linear actuator forces from a full-scale prototype machine

Workspace optimisation of a reconfigurable parallel kinematic manipulator

One significant limitation of parallel kinematic machines in the past has been the limited workspace to installation space ratio. The Gantry-Tau is an example of a relatively new PKM which improves this ratio by allowing a change of assembly mode without internal link collisions or collisions between the links and the moving TCP platform. The avoidance of these internal collisions is made possible by using a triangular-mounted link pair. This paper introduces for the first time the unreachable workspace for the Gantry-Tau. The unreachable area can occur in the middle of the workspace of reconfigurable PKMs with fixed length actuators. It is important to eliminate unreachable areas when designing the Gantry-Tau PKM because they appear in the middle of the workspace which is often the most useful part of the workspace. A geometric approach which describes both the reachable and unreachable workspace has been developed. This approach is significantly faster than analytical workspace calculation methods based on the inverse kinematics. Because of the fast computational speed of the geometric approach presented in this paper, the method is an ideal candidate for inclusion in a design optimisation framework. An optimised kinematic design of the Gantry-Tau is presented in the paper

Kinematic optimisation of the gantry-tau parallel kinematic manipulator with respect to its workspace

The Gantry-Tau is a recently developed parallel kinematic manipulator (PKM). Since the actuators are stationary it possesses the following characteristics: high speed, high acceleration, small moving mass and high static and dynamic accuracy. Since all link forces in the structure are axial, high stiffness can also be achieved. One of the main advantages of the Gantry-Tau machine is a large workspace area in comparison with traditional parallel machines. However, parameters of the machine, such as link lengths and dimension of support frames, can be difficult to design manually. In this paper we present a method to optimise such parameters to achieve the largest possible workspace. The problem is solved by using a non-linear optimization routine and imposing the parameterization on the midpoints of three spheres generated by the parallel links that intersect at the tool center point (TCP)