Static measuring model and deadweight compensation of a Stewart platform based force/torque sensor

The static measuring model and the deadweight compensation of a Stewart platform based force/torque sensor have been studied in this paper. Firstly, some preliminary kinematics of this sensor is presented. Coordinates attached to every links are established, and the transforming relations between link frames and other frames are derived. Then, the static measuring model and the deadweight compensation of the sensor are produced. In the modeling, forces on links are composed based on an analytic method, and the resultant forces and torques obtained can be used as the measuring model. The weight need to be compensated of the whole mechanism is divided into two parts: links weights and top platform weight. The compensation of the links weights is involved in static modeling. And the top platform weight is compensated, subsequently. Finally, some experiments are carried out, and the results verify the validity of the static measuring model and the deadweight compensation

An Overview of Kinematic and Calibration Models Using Internal/External Sensors or Constraints to Improve the Behavior of Spatial Parallel Mechanisms

This paper presents an overview of the literature on kinematic and calibration models of parallel mechanisms, the influence of sensors in the mechanism accuracy and parallel mechanisms used as sensors. The most relevant classifications to obtain and solve kinematic models and to identify geometric and non-geometric parameters in the calibration of parallel robots are discussed, examining the advantages and disadvantages of each method, presenting new trends and identifying unsolved problems. This overview tries to answer and show the solutions developed by the most up-to-date research to some of the most frequent questions that appear in the modelling of a parallel mechanism, such as how to measure, the number of sensors and necessary configurations, the type and influence of errors or the number of necessary parameters