Torgny Brogårdh

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One key competence for robot manufacturers is robot control, defined as all the technologies needed to control the electromechanical system of an industrial robot. By means of modeling, identification, optimization, and model-based control it is possible to reduce robot cost, increase robot performance, and solve requirements from new automation concepts(More)
In the last decades, an increasing attention has been paid to the study of different parallel structure mechanisms and their applications, mainly triggered by Stewart that presented an aircraft simulator system. Parallel structure features provide big advantages in potential applications. For example, parallel robots may give higher speed and acceleration,(More)
This paper presents a new error kinematic model containing twelve parameters for the three linear actuators of the Gantry-Tau parallel kinematic manipulator. Three different types of measurement equipment, laser interferometers, linear encoders and double-ball bars, can successfully be used to calibrate the linear actuators. A method for selecting an(More)
In this paper the invited session and the 4 original contributions are described first. Then the details of the first paper in the invited session is presented. In this first paper a new method for calculating the dynamic stiffness (frequency response) of parallel kinematic machines (PKMs) with six links, or Hexapods, is presented. The method assumes that(More)
This paper describes the design and implementation of a platform for fast external sensor integration in an industrial robot control system. As an application and motivating example, the implementation of force controlled grinding and deburring within the AUTOFETT-project (EU Growth Programme) is reported.
Here we present a method for high-precision drilling using an industrial robot with high-bandwidth force feedback, which is used for building up pressure to clamp-up an end-effector to the work-piece surface prior to drilling. The focus is to eliminate the sliding movement (skating) of the end-effector during the clamp-up of the end-effector to the(More)
Friction is the result of complex interactions between contacting surfaces in a nanoscale perspective. Depending on the application, the different models available are more or less suitable. Available static friction models are typically considered to be dependent only on relative speed of interacting surfaces. However, it is known that friction can be(More)
Recent findings indicate that lithium belongs to the group of rather exclusive agents which affect the period of circadian clocks: The period of the cir­ cadian petal movements of Kalanchoe is increased by about 2 hours in 5 m M LiCl 2. In the present paper we will report an action of lithium on a much more rapid oscillation, which under certain circum­(More)