Six component force-torque sensors using Gough-Stewart platform manipulators (original) (raw)
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Analysis and experimental evaluation of a Stewart platform-based force/torque sensor
1992
The kinematic analysis and experimentation of a force/torque sensor whose design is based on the mechanism of the Stewart Platform are discussed. Besides being used for measurement of forces/torques, the sensor also serves as a compliant platform which provides passive compliance during a robotic assembly task. It consists of two platforms, the upper compliant platform (UCP) and the lower compliant
Design and development of a Stewart platform based force–torque sensor
Mechatronics, 2001
This paper details the design and development of a force±torque sensor based on the Stewart platform structure. The optimal synthesis of the sensor structure is performed with the objective of achieving well-conditioned transformation between the input and output forces. The in¯uence of size of platform on sensitivity and the load bearing capacity are discussed in the light of capabilities of available sensing elements. Thus, the design is obtained by satisfying the dual objective of isotropy and sensitivity of the force±torque sensor. Maximization of signal to noise ratio (S/N ratio) is considered at various stages in arriving at various component shapes and dimensions. The above design has been implemented in the development of a compact force±torque sensor. Ó
A force–torque sensor based on a Stewart Platform in a near-singular configuration
Mechanism and Machine Theory, 2004
It is well known that a parallel mechanism at a singular configuration can gain one or more degrees of freedom instantaneously, and at such a configuration it cannot resist externally applied force/torque along certain directions. At near-singular configurations, small applied force/torque in a certain specific direction can give rise to large forces in the links, thereby resulting in mechanical magnification in link forces. This key idea is used, with a Stewart Platform, in a near-singular configuration, to design a directionally sensitive force-torque sensor. The concept of near-singular configuration and magnification is developed analytically and numerically with the help of a simple planar truss with rotary and flexure joints. A finite element analysis shows that a properly designed flexure joint approximates a rotary joint reasonably well, thus avoiding friction and non-linearities associated with rotary joints. The concept of force magnification and flexural joints is next extended to a Stewart Platform at a near-singular configuration. It is verified, using finite element analysis, that the Stewart Platform at a near-singular configuration with flexural hinges shows large forces in the legs for small external forces and torques applied in certain directions, and thus can be a good design for a highly sensitive force-torque sensor for certain components of applied force/torque. It is also shown, from a singularity analysis of the Stewart Platform, that sensitivity to other components of external force/torque can be obtained by using different near-singular configurations. The theoretical concepts are demonstrated with a prototype sensor which is sensitive to two components of the externally applied force and one component of the externally applied moment. Mechanism and Machine Theory 972 R. Ranganath et al. / Mechanism and Machine Theory 39 (2004) 971-998 Ã p is a 3 · 3 matrix of principal moments at centre of platform. 980 R. Ranganath et al. / Mechanism and Machine Theory 39 (2004) 971-998
A near-singular, flexure jointed, moment sensitive Stewart platform based force-torque sensor
A force-torque sensor capable of accurate measurement of the three components of externally applied forces and moments is required for force control in robotic applications involving assembly operations. The goal in this paper is to design a Stewart platform based forcetorque sensor at a near-singular configuration sensitive to externally applied moments. In such a configuration, we show an enhanced mechanical amplification of leg forces and thereby higher sensitivity for the applied external moments. In other directions, the sensitivity will be that of a normal load sensor determined by the sensitivity of the sensing element and the associated electronic amplification, and all the six components of the force and torque can be sensed.
Strain Analysis of Six-Axis Force/Torque Sensors Based on Analytical Method
IEEE Sensors Journal, 2017
Reasonable stress and strain distribution are essential for the design of six-axis force/torque sensors. In order to improve the strain distribution, the specific parameters which affect stress and strain distribution need to be found. The numerical solutions of stress and strain on the elastic beam of six-axis force/torque sensors can be quickly obtained by finite element analysis simulation tool, such as ANSYS, but the specific parameters which affect stress and strain distribution cannot be achieved. In this paper, a novel six-axis force/torque sensor scheme with small size and cross beam structure was presented. Then, the mechanical model and analytic equations based on Timoshenko beam theory were established to obtain the analytical solutions of strain. The comparison shows that the analytical solutions and numerical solutions are in good agreement, which indicates that the analytical method is feasible. Finally, the main parameters which affect the strain value and the measure accuracy were analyzed. The analysis results show that the design of six-axis force/torque sensors with cross beam structure can be optimized according to the parameters that affect the stress and strain distribution, if sufficient restrictions are offered. Index Terms-Six-axis force/torque sensors, Timoshenko beam theory, strain analysis, analytical and numerical solutions, optimal solution of structure. I. INTRODUCTION A CQUISITION of multi-dimensional force information is one of the most important senses for intelligent robots. Six-axis force/torque sensors can detect the full force information of three-dimensional space of the robot simultaneously, i.e., three force components: Fx, Fy, Fz and three torque components:Mx, My, Mz of three spatial coordinate axes. As a result, they are the essential parts to improve the intelligence and manipulative level of robots [1]. Such sensors are now widely used for force/torque senses of robots control in various occasions, such as zero force teaching [2], automatic flexible assembly [3], robots multi-hand cooperation [4], robot teleoperation system [5], [6], robotic surgery and rehabilitation training [7], etc.
Study of an Force Torque Sensor Using in Six Dof at Micro Manipulation Application
2015
This paper presents the design fabrication and characterization of a piezoresistive 6 degree of freedom force and torque sensor to be used in micro manipulation. The mechanical structure of the device consists of seven suspended beams and a calibration structure, which can be replaced by micro manipulation tools such as micro grippers or probes. The geometry of the beam and the location of the piezoresistors in the structure are optimized to reduce crosstalk and improve the sensitivity. A linear regression model is fitted to the calibration data to extract the force and torque from the resistance variations detected in the piezoresistors. The device has been fabricated with an IC compatible process and successfully characterized. Aspects of control implementation concerning a joint torque sensor are discussed and a technique to its correction and calibration is presented. 6level control scheme is used for the intrinsic to the 6 time scale dynamics of the system. For the first part o...
State and dynamic behavior of a high stiffness stewart platform-based force/torque sensor
Journal of Robotic Systems, 1995
The performance of a Stewart platform-based force/torque sensor is analyzed. The influence of sensor geometry is assessed with particular reference to the characteristic orientation angles of the arms connecting the platforms, which consist of singleaxis bidirectional force transducers. Static and dynamic performance is analyzed and compared with experimental tests. 0 1995 / o h Wile!/ 6 Soils, Iitc.
2016 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2016
This paper presents a methodology for the development of a multi-axis force/torque sensor based on optoelectronic technology. The advantages of using this sensing principle are the low manufacturing costs, the simple fabrication, and the immunity to electrical noise. The force/ torque sensor makes use of six optical sensors: each sensor measures the displacement of a reflective surface that moves integrally with a simply-supported beam. The proposed mechanical structure allows for a variety of shapes on the mechanical structure to be easily adaptable to many robot applications. In this paper, we present a five-axis force/torque sensor based on this optoelectronic principle. To measure force/torque components, two identical three-DoF force/torque sensor structures (comprised of three beams) are mounted on top of each other. Photo sensors and mirrors are fixed inside the structure to measure the six beam deflections. In this paper, we describe the sensor structure, design, fabrication, calibration, and verify our sensor development methodology.
Development of a new “6-axis” force connected sensor
19th International Congress of Metrology (CIM2019), 2019
This new sensor project has been initiated mainly in order to take measurements in the field of biomechanics during motions of human bodies. For that, it’s necessary to detect the efforts at the contacts with these human bodies in real situation, such as during working, walking, running, biking and so on. Up to now, most of 6 components force sensors which are used, for instance are sensors with each component measuring device as perfectly as possible decoupled from each other’s. This leads to expansive or very expansive sophisticated sensors. The present sensor is a stand-alone wireless, small sized 6-axis force sensor with a powerful and precise conditioning and acquisition system. The sensitive cell is a raw Stewart mechanical structure (strain-gages based) with, conversely to usual multicomponent sensors, force and moment components not decoupled at all, but optimally coupled. Owing to the powerful numerical capabilities of the sensor, the 6 effective components of a given mecha...