Posture Optimization Based on Both Joint Parameter Error and Stiffness for Robotic Milling

Based on the current situation of high precision and comparatively low APA (absolute positioning accuracy) in industrial robots, a calibration method to enhance the APA of industrial robots is proposed. In view of the "hidden" characteristics of the RBCS (robot base coordinate system) and the FCS (flange coordinate system) in the measurement process, a comparatively general measurement and calibration method of the RBCS and the FCS is proposed, and the source of the robot terminal position error is classified into three aspects: positioning error of industrial RBCS, kinematics parameter error of manipulator, and positioning error of industrial robot end FCS. The robot position error model is established, and the relation equation of the robot end position error and the industrial robot model parameter error is deduced. By solving the equation, the parameter error identification and the supplementary results are obtained, and the method of compensating the error by using the robot joint angle is realized. The Leica laser tracker is used to verify the calibration method on ABB IRB120 industrial robot. The experimental results show that the calibration method can effectively enhance the APA of the robot.

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Sensorless LC Filter Implementation for Permanent Magnet Machine Drive Using Observer-Based Voltage and Current Estimation

Sensors ◽

10.3390/s21113596 ◽

2021 ◽

Vol 21 (11) ◽

pp. 3596

Author(s):

Chia-Ming Liang ◽

Yi-Jen Lin ◽

Jyun-You Chen ◽

Guan-Ren Chen ◽

Shih-Chin Yang

Keyword(s):

Permanent Magnet ◽

High Speed ◽

Pulse Width Modulation ◽

Output Current ◽

Current Harmonics ◽

Pwm Inverter ◽

Current Estimation ◽

Filter Output ◽

Lc Filter ◽

Parameter Error

For pulse width modulation (PWM) inverter drives, an LC filter can cascade to a permanent magnet (PM) machine at inverter output to reduce PWM-reflected current harmonics. Because the LC filter causes resonance, the filter output current and voltage are required for the sensorless field-oriented control (FOC) drive. However, existing sensors and inverters are typically integrated inside commercial closed-form drives; it is not possible for these drives to obtain additional filter output signals. To resolve this integration issue, this paper proposes a sensorless LC filter state estimation using only the drive inside current sensors. The design principle of the LC filter is first introduced to remove PWM current harmonics. A dual-observer is then proposed to estimate the filter output current and voltage for the sensorless FOC drive. Compared to conventional model-based estimation, the proposed dual-observer demonstrates robust estimation performance under parameter error. The capacitor parameter error shows a negligible influence on the proposed observer estimation. The filter inductance error only affects the capacitor current estimation at high speed. The performance of the sensorless FOC drive using the proposed dual-observer is comparable to the same drive using external sensors for filter voltage and current measurement. All experiments are verified by a PM machine with only 130 μH phase inductance.

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Improving feasibility of robotic milling through robot placement optimisation

Robotics and Computer-Integrated Manufacturing ◽

10.1016/j.rcim.2010.04.001 ◽

2010 ◽

Vol 26 (5) ◽

pp. 517-525 ◽

Cited By ~ 60

Author(s):

George-Christopher Vosniakos ◽

Elias Matsas

Keyword(s):

Robotic Milling ◽

Robot Placement

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Precision Robotic Milling of Fiberglass Shims in Aircraft Wing Assembly Using Laser Tracker Feedback

SAE International Journal of Aerospace ◽

10.4271/01-15-01-0006 ◽

2022 ◽

Vol 15 (1) ◽

Author(s):

Vinh Nguyen ◽

Toni Cvitanic ◽

Matthew Baxter ◽

Konrad Ahlin ◽

Joshua Johnson ◽

...

Keyword(s):

Laser Tracker ◽

Aircraft Wing ◽

Robotic Milling

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An Increase in Accuracy of Robotic Milling

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.865.450 ◽

2017 ◽

Vol 865 ◽

pp. 450-456 ◽

Cited By ~ 1

Author(s):

Yu.V. Ilyukhin ◽

Ruslan Kolesnichenko

Keyword(s):

Computer Simulation ◽

Impedance Control ◽

Dynamic Stiffness ◽

Milling Process ◽

Motor Drives ◽

Theoretical Research ◽

Robotic Milling ◽

Servo Drives ◽

And Performance ◽

Increase In Accuracy

The results of the theoretical research and the computer simulation, aimed at increase in accuracy of robotic milling, are presented in the article. An analysis of the mathematical models of the system «technological robot – milling process» is conducted. The prospects of the usage of precision geared dual motor servo drives and trajectory-impedance control systems are underlined. A computer research of the tool movement accuracy during the robotic cylindrical up-milling process, depending on path velocity of the milling cutter and rated value of the cutting depth, has been carried out. Two types of manipulators have been considered: a manipulator with traditional geared servo drives with one motor and a manipulator with the suggested precision dual motor drives. In order to measure accuracy of movements during the computer simulation process a deviation of the tool, normal to the desired trajectory of its movement, has been defined. The results testify the facts that dual motor servo drives allow us to significantly increase dynamic stiffness of technological robots and they promote increasing accuracy and performance of robotic milling.

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