scholarly journals Error Analysis of a Spherical Capacitive Sensor for the Micro-Clearance Detection in Spherical Joints

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 837 ◽  
Author(s):  
Wen Wang ◽  
Wenjun Qiu ◽  
He Yang ◽  
Keqing Lu ◽  
Zhanfeng Chen ◽  
...  
Keyword(s):  
Error Analysis ◽  
Mathematical Models ◽  
Machine Tools ◽  
Medical Equipment ◽  
Measurement Accuracy ◽  
Capacitive Sensor ◽  
Differential Capacitance ◽  
Industrial Robots ◽  
Error Sources ◽  
Inclined Angle

Spherical joints have attracted increasing interest in the engineering applications of machine tools, industrial robots, medical equipment, and so on. As one of the promising methods of detecting the micro-clearance in spherical joints, the measurement accuracy of a spherical capacitive sensor could be affected by imperfectness during the manufacturing and installation of the sensor. This work presents error analysis of a spherical capacitive sensor with a differential structure and explores the dependence of the differential capacitance on manufacturing and the installation imperfectness. Five error sources are examined: the shape of the ball and the capacitive plate, the axial and radial offset of the plate, and the inclined installation of the plate. The mathematical models for calculating the capacitance errors of the spherical capacitive sensor are deduced and validated through a simulation using Ansoft Maxwell. The results show that the measurement accuracy of the spherical capacitive sensor is significantly affected by the shape of plates and ball, the axial offset, and the inclined angle of the plate. In contrast, the effect of the radial offset of the plate is quite small.

scholarly journals An Improved Capacitive Sensor for Detecting the Micro-Clearance of Spherical Joints

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2694 ◽  
Author(s):  
Wen Wang ◽  
Wenjun Qiu ◽  
He Yang ◽  
Haimei Wu ◽  
Guang Shi ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Real Time ◽  
Measurement Accuracy ◽  
Detection Method ◽  
Capacitive Sensor ◽  
Parallel Manipulators ◽  
Differential Capacitance ◽  
Industrial Robots ◽  
The Mathematical Model ◽  
Fringe Effect

Due to the flexible and compact structures, spherical joints are widely used in parallel manipulators and industrial robots. Real-time detection of the clearance between the ball and the socket in spherical joints is beneficial to compensate motion errors of mechanical systems and improve their transmission accuracy. This work proposes an improved capacitive sensor for detecting the micro-clearance of spherical joints. First, the structure of the capacitive sensor is proposed. Then, the mathematical model for the differential capacitance of the sensor and the eccentric micro-displacement of the ball is deduced. Finally, the capacitance values of the capacitive sensor are simulated with Ansoft Maxwell. The simulated values of the differential capacitances at different eccentric displacements agree well with the theoretical ones, indicating the feasibility of the proposed detection method. In addition, the simulated results show that the proposed capacitive sensor could effectively reduce the capacitive fringe effect, improving the measurement accuracy.

scholarly journals A Novel Method for the Micro-Clearance Measurement of a Precision Spherical Joint Based on a Spherical Differential Capacitive Sensor

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3366 ◽  
Author(s):  
Wen Wang ◽  
He Yang ◽  
Min Zhang ◽  
Zhanfeng Chen ◽  
Guang Shi ◽  
...  
Keyword(s):  
Capacitive Sensor ◽  
Differential Capacitance ◽  
Industrial Robots ◽  
Parallel Mechanisms ◽  
Spherical Joint ◽  
Compact Structure ◽  
Spacing Variation ◽  
Novel Method ◽  
The Mathematical Model ◽  
Fringe Effect

A spherical joint is a commonly used mechanical hinge with the advantages of compact structure and good flexibility, and it becomes a key component in many types of equipment, such as parallel mechanisms, industrial robots, and automobiles. Real-time detection of a precision spherical joint clearance is of great significance in analyzing the motion errors of mechanical systems and improving the transmission accuracy. This paper presents a novel method for the micro-clearance measurement with a spherical differential capacitive sensor (SDCS). First, the structure and layout of the spherical capacitive plates were designed according to the measuring principle of capacitive sensors with spacing variation. Then, the mathematical model for the spatial eccentric displacements of the ball and the differential capacitance was established. In addition, equipotential guard rings were used to attenuate the fringe effect on the measurement accuracy. Finally, a simulation with Ansoft Maxwell software was carried out to calculate the capacitance values of the spherical capacitors at different eccentric displacements. Simulation results indicated that the proposed method based on SDCS was feasible and effective for the micro-clearance measurement of the precision spherical joints with small eccentricity.

scholarly journals Ball Bar Measurement on Machine Tools with Rotary Axes

2012 ◽  
Vol 6 (2) ◽  
pp. 180-187 ◽  
Author(s):  
Yukitoshi Ihara ◽  
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Industrial Robots ◽  
Error Sources ◽  
Rotary Axes ◽  
Rotary Axis ◽  
Test Conditions ◽  
Ball Bar ◽  
Articulated Robots ◽  
Five Axis

A ball bar is a very convenient device for measuring the motion accuracy of machine tools. Some trials have also been done for measuring motion accuracy of industrial robots. Nowadays, multi-axis machines such as five-axis machining centers are very popular, and therefore, there is increased demand for checking their accuracy. This paper introduces an idea for checking the motion accuracy of five-axis machining centers and diagnosing error sources by reviewing trial measurements on articulated industrial robots. There are two problems. The first problem is that the ball bar can measure only distances, and the second problem is that the ball bar is a linear device and therefore not suitable for the rotary axis motion of 5-axis machines and articulated robots. Finally, the test conditions for the measurement of the motion accuracy of a machine tool showing conical motion, by using the ball bar and ISO/DIS 10791-6 (which is currently being edited) are reviewed and verified.

Spanende Bearbeitung mit Industrierobotern und Bearbeitungszentren*/Machining with industrial robots and machining centers – Analysis of the achievable component qualities in woodworking

2019 ◽  
Vol 109 (09) ◽  
pp. 650-655
Author(s):  
C. Menze ◽  
D. Becker ◽  
T. Stehle ◽  
H.-C. Möhring ◽  
N. Helfesrieder ◽  
...  
Keyword(s):  
Machine Tools ◽  
High Potential ◽  
Industrial Robots ◽  
Metal Industry ◽  
Great Flexibility ◽  
Process Forces

Industrieroboter bieten eine große Flexibilität und einen großen Arbeitsraum bei verhältnismäßig geringen Investitionskosten. Gegenüber spanenden Werkzeugmaschinen sind die Steifigkeiten und Bahngenauigkeiten von Robotern jedoch geringer. Dennoch bieten sie für die Holzbearbeitung großes Potential, da die Prozesskräfte gewöhnlich kleiner und die Toleranzen höher sind als im Metallbereich. Dieser Beitrag stellt einen Vergleich der erzielbaren Bauteilqualitäten bei der Holzbearbeitung mit Industrierobotern und Bearbeitungszentren vor.   Industrial robots provide great flexibility and a large working area at relatively low investment costs. However, their stiffness and path accuracy are generally lower compared to machine tools. Still, they offer high potential for woodworking, as the process forces are usually smaller and the tolerances higher than in the metal industry. This paper presents a comparison of the achievable component qualities in woodworking with industrial robots and machining centers.

Mathematical models for base calibration in industrial robots

2017 ◽  
Vol 37 (11) ◽  
pp. 995-1000 ◽  
Author(s):  
O. N. Krakhmalev ◽  
D. I. Petreshin ◽  
O. N. Fedonin
Keyword(s):  
Mathematical Models ◽  
Industrial Robots

scholarly journals Robot Modeling for Physical Rehabilitation

Robotics ◽  
2013 ◽  
pp. 1212-1232 ◽  
Author(s):  
Rogério Sales Gonçalves ◽  
João Carlos Mendes Carvalho
Keyword(s):  
Mathematical Models ◽  
Three Dimensional ◽  
Mechanical Systems ◽  
Industrial Robots ◽  
Limb Movements ◽  
Rehabilitation Robots ◽  
Wide Range ◽  
Movable Platform ◽  
Human Limb ◽  
Robot Modeling

The science of rehabilitation shows that repeated movements of human limbs can help the patient regain function in the injured limb. There are three types of mechanical systems used for movement rehabilitation: robots, cable-based manipulators, and exoskeletons. Industrial robots can be used because they provide a three-dimensional workspace with a wide range of flexibility to execute different trajectories, which are useful for motion rehabilitation. The cable-based manipulators consist of a movable platform and a base, which are connected by multiple cables that can extend or retract. The exoskeleton is fixed around the patient's limb to provide the physiotherapy movements. This chapter presents a summary of the principal human limb movements, a review of several mechanical systems used for rehabilitation, as well as common mathematical models of such systems.

Error sources and models of the laser tracker without a beam steering mirror

2021 ◽  
Author(s):  
Radoslav Choleva ◽  
Alojz Kopáčik
Keyword(s):  
Measurement Accuracy ◽  
Beam Steering ◽  
Systematic Errors ◽  
Error Modeling ◽  
Laser Tracker ◽  
High Demand ◽  
Error Sources ◽  
Error Models ◽  
Measurement Results

AbstractThe laser tracker is a widely used instrument in many industrial and metrological applications with high demand measurement accuracy. Imperfections in construction and misalignment of individual parts deliver systematic errors in the measurement results. All error sources need to be identified and reduced to the minimum to achieve the best possible accuracy. The paper summarizes error sources of the laser tracker without beam steering mirror with emphasis on error modeling. Descriptions of error models are provided for the static and kinematic type of measurement.

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