1. Project Goals: The Hardware: The Problem: Results to Date:
Robust Nonlinear Observer for Non-collocated Flexible Motion System
Project Goals:
The Hardware:
Flexible Beam: 1/8” 1018 Steel, 12.5” Long, 1 3/8” Wide
Actuator: Anorad Linear Motor
Sensors: PCB Accelerometer, Anorad Linear Encoder
Controller: LabVIEW Realtime 8.5 Target-PC with NI-6052E DAQ Board
Contribute to the field of active vibration suppression in motion systems.
Examine the robustness of a Sliding Mode Observer in presence of non-collocation and model uncertainty.
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advisor
The Problem:
Wayne Book 1 2 3 4 5 6
Results to Date:
Robotic arms are subject to bending, torsion and axial compression. In certain applications, to ensure accuracy and repeatability of the useful end-point of the robotic arm, the flexible nature of the arm must be taken into account during design. Immediate benefits of this research include:
System identification of rigid sub-system and flexible sub-system has been completed. The flexible sub-system has been modeled using an Assumed Modes Method model as well as a lower-order lumped parameter model. Controllers and estimators based on both models have been evaluated.
Comprehensive simulation studies of the closed-loop system with the Kalman Filter and the Sliding Mode Observer have been completed. Simulations have verified the robustness properties of the sliding mode observer. Improved estimation can lead to better reference tracking in a closed-loop system with reduced tip excitation of the single flexible link during motion.
The Kalman filter and the Sliding Mode Observer have been implemented on the test-bed in the LabVIEW programming environment. The benefits of the Sliding Mode Observer on the physical system are still being evaluated.
Magnitude (dB)
Motion of a Single Flexible Link
student
Improved control of long-reach space and lower-cost industrial manipulators.
Improved accuracy and precision of general robotic manipulators with non-collocated actuators and sensors.
Frequency (Hz)
Mohsin Waqar
System Identification:
Model vs. Experimental Data
CAMotion
Depalletizer
With Kalman Filter
With Sliding Mode Observer
NASA Space Manipulator
Tip Position (m)
The Approach:
Produce a useful model for a single flexible link which represents the non-minimum phase behavior accurately. Research and identify suitable state estimators and select an appropriate feedback control scheme. Benchmark the closed-loop estimator performance by examining robustness of the closed-loop system to parameter uncertainty.
Time (sec)
Industry
Sponsors:
LabVIEW Simulation:
State Feedback Control
E, I, ρ, A, L m F
w(x,t) x
No Control
With Control
Model of Flexible Sub-System based on
Assumed Modes Method
Tip Accel. (m/s2)
Time (sec)
Physical System:
Regulator with Kalman Filter
Next Steps:
Continue to develop and document a systematic approach to tuning observer parameters on the physical system.
Integrate flexible link tip position measurements supplied by a vision system with existing measurements.
Explain the pictures if not obvious
Closed-Loop Control of Experimental Test-Bed