Development of a 3-PRR Precision Tracking System with Full Closed-Loop Measurement and Control

Laser sensors can be used to measure distances to objects and their related parameters (displacements, position, surface profiles and velocities). Laser sensors are based on many different optical techniques, such as triangulation, time-of-flight, confocal and interferometric sensors. As laser sensor technology has improved, the size and cost of sensors have decreased, which has led to the widespread use of laser sensors in many areas. In addition to traditional manufacturing industry applications, laser sensors are increasingly used in robotics, surveillance, autonomous driving and biomedical areas. This paper outlines some of the recent efforts made towards laser sensors for displacement, distance and position.

Section: Contributionsmentioning

confidence: 99%

“…In [4], position of prismatic–revolute–revolute (three links with each link consisting of a prismatic pair and two rotating pairs) parallel platform is measured using three laser triangulation sensors and linear grating encoders. The objective is to develop a three-degrees-of-freedom full closed-loop control precision tracking system.…”

Section: Contributionsmentioning

confidence: 99%

Laser Sensors for Displacement, Distance and Position

Suh

2019

“…Three two-dimensional accelerometers were installed on the base and the platform, respectively. Four two-dimensional position sensors and four laser light sources were fixed between the base and the platform [29]. CPU data acquisition cards and motion control cards were all integrated on the base.…”

Section: Modelingmentioning

confidence: 99%

Modeling and Control of a Six Degrees of Freedom Maglev Vibration Isolation System

Cui

Zhao

et al. 2019

The environment in space provides favorable conditions for space missions. However, low frequency vibration poses a great challenge to high sensitivity equipment, resulting in performance degradation of sensitive systems. Due to the ever-increasing requirements to protect sensitive payloads, there is a pressing need for micro-vibration suppression. This paper deals with the modeling and control of a maglev vibration isolation system. A high-precision nonlinear dynamic model with six degrees of freedom was derived, which contains the mathematical model of Lorentz actuators and umbilical cables. Regarding the system performance, a double closed-loop control strategy was proposed, and a sliding mode control algorithm was adopted to improve the vibration isolation performance. A simulation program of the system was developed in a MATLAB environment. A vibration isolation performance in the frequency range of 0.01–100 Hz and a tracking performance below 0.01 Hz were obtained. In order to verify the nonlinear dynamic model and the isolation performance, a principle prototype of the maglev isolation system equipped with accelerometers and position sensors was developed for the experiments. By comparing the simulation results and the experiment results, the nonlinear dynamic model of the maglev vibration isolation system was verified and the control strategy of the system was proved to be highly effective.

“…The vast majority of industrial and scientific applications use optical encoders for a position measurement and closed-loop position control, for example, machine tools [ 1 , 2 , 3 , 4 , 5 ], tracking systems [ 6 , 7 , 8 ], industrial robots [ 9 , 10 , 11 , 12 , 13 ], positioning stages [ 14 , 15 , 16 , 17 ], and so on. All these technological machines work under various environment conditions such as temperature, humidity, mechanical vibration, etc.…”

Section: Introductionmentioning

confidence: 99%

Thermal and Geometric Error Compensation Approach for an Optical Linear Encoder

Gurauskis

Kilikevičius

Kasparaitis

2021

Linear displacement measuring systems, like optical encoders, are widely used in various precise positioning applications to form a full closed-loop control system. Thus, the performance of the machine and the quality of its technological process are highly dependent on the accuracy of the linear encoder used. Thermoelastic deformation caused by a various thermal sources and the changing ambient temperature are important factors that introduce errors in an encoder reading. This work presents an experimental realization of the real-time geometric and thermal error compensation of the optical linear encoder. The implemented compensation model is based on the approximation of the tested encoder error by a simple parametric function and calculation of a linear nature error component according to an ambient temperature variation. The calculation of a two-dimensional compensation function and the real-time correction of the investigated linear encoder position readings are realized by using a field programmable gate array (FPGA) computing platform. The results of the performed experimental research verified that the final positioning error could be reduced up to 98%.