scholarly journals Visuomotor feedback gains upregulate during the learning of novel dynamics

2012 ◽  
Vol 108 (2) ◽  
pp. 467-478 ◽  
Author(s):  
Sae Franklin ◽  
Daniel M. Wolpert ◽  
David W. Franklin
Keyword(s):  
Control System ◽  
Force Field ◽  
Feedforward Control ◽  
Early Stage ◽  
Corrective Feedback ◽  
Motor Command ◽  
Sensorimotor Control ◽  
Early Learning ◽  
Feedback Gain ◽  
Feedforward Controller

At an early stage of learning novel dynamics, changes in muscle activity are mainly due to corrective feedback responses. These feedback contributions to the overall motor command are gradually reduced as feedforward control is learned. The temporary increased use of feedback could arise simply from the large errors in early learning with either unaltered gains or even slightly downregulated gains, or from an upregulation of the feedback gains when feedforward prediction is insufficient. We therefore investigated whether the sensorimotor control system alters feedback gains during adaptation to a novel force field generated by a robotic manipulandum. To probe the feedback gains throughout learning, we measured the magnitude of involuntary rapid visuomotor responses to rapid shifts in the visual location of the hand during reaching movements. We found large increases in the magnitude of the rapid visuomotor response whenever the dynamics changed: both when the force field was first presented, and when it was removed. We confirmed that these changes in feedback gain are not simply a byproduct of the change in background load, by demonstrating that this rapid visuomotor response is not load sensitive. Our results suggest that when the sensorimotor control system experiences errors, it increases the gain of the visuomotor feedback pathways to deal with the unexpected disturbances until the feedforward controller learns the appropriate dynamics. We suggest that these feedback gains are upregulated with increased uncertainty in the knowledge of the dynamics to counteract any errors or disturbances and ensure accurate and skillful movements.

scholarly journals Rapid visuomotor feedback gains are tuned to the task dynamics

2017 ◽  
Vol 118 (5) ◽  
pp. 2711-2726 ◽  
Author(s):  
Sae Franklin ◽  
Daniel M. Wolpert ◽  
David W. Franklin
Keyword(s):  
Control System ◽  
Force Field ◽  
Feedback System ◽  
Sensorimotor Control ◽  
Motor Memory ◽  
Feedback Gain ◽  
Adaptation Process ◽  
Fourfold Increase ◽  
Lateral Resistance ◽  
Left And Right

Adaptation to novel dynamics requires learning a motor memory, or a new pattern of predictive feedforward motor commands. Recently, we demonstrated the upregulation of rapid visuomotor feedback gains early in curl force field learning, which decrease once a predictive motor memory is learned. However, even after learning is complete, these feedback gains are higher than those observed in the null field trials. Interestingly, these upregulated feedback gains in the curl field were not observed in a constant force field. Therefore, we suggest that adaptation also involves selectively tuning the feedback sensitivity of the sensorimotor control system to the environment. Here, we test this hypothesis by measuring the rapid visuomotor feedback gains after subjects adapt to a variety of novel dynamics generated by a robotic manipulandum in three experiments. To probe the feedback gains, we measured the magnitude of the motor response to rapid shifts in the visual location of the hand during reaching. While the feedback gain magnitude remained similar over a larger than a fourfold increase in constant background load, the feedback gains scaled with increasing lateral resistance and increasing instability. The third experiment demonstrated that the feedback gains could also be independently tuned to perturbations to the left and right, depending on the lateral resistance, demonstrating the fractionation of feedback gains to environmental dynamics. Our results show that the sensorimotor control system regulates the gain of the feedback system as part of the adaptation process to novel dynamics, appropriately tuning them to the environment. NEW & NOTEWORTHY Here, we test whether rapid visuomotor feedback responses are selectively tuned to the task dynamics. The responses do not exhibit gain scaling, but they do vary with the level and stability of task dynamics. Moreover, these feedback gains are independently tuned to perturbations to the left and right, depending on these dynamics. Our results demonstrate that the sensorimotor control system regulates the feedback gain as part of the adaptation process, tuning them appropriately to the environment.

scholarly journals Adaptive Feedforward Control of a Pressure Compensated Differential Cylinder

2020 ◽  
Vol 10 (21) ◽  
pp. 7847
Author(s):  
Konrad Johan Jensen ◽  
Morten Kjeld Ebbesen ◽  
Michael Rygaard Hansen
Keyword(s):  
Control System ◽  
Root Mean Square ◽  
Motion Control ◽  
Experimental Verification ◽  
Feedforward Control ◽  
Position Error ◽  
Mean Square ◽  
Model Uncertainties ◽  
Feedforward Controller ◽  
Adaptive Feedforward

This paper presents the design, simulation and experimental verification of adaptive feedforward motion control for a hydraulic differential cylinder. The proposed solution is implemented on a hydraulic loader crane. Based on common adaptation methods, a typical electro-hydraulic motion control system has been extended with a novel adaptive feedforward controller that has two separate feedforward states, i.e, one for each direction of motion. Simulations show convergence of the feedforward states, as well as 23% reduction in root mean square (RMS) cylinder position error compared to a fixed gain feedforward controller. The experiments show an even more pronounced advantage of the proposed controller, with an 80% reduction in RMS cylinder position error, and that the separate feedforward states are able to adapt to model uncertainties in both directions of motion.

Adaptive Feedforward Vibration Control of Flexible Structure With Discrete Sliding Mode Controller

2006 ◽  
Author(s):  
J. Fei
Keyword(s):  
Control System ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Flexible Beam ◽  
Sliding Mode Controller ◽  
Control Scheme ◽  
Feedforward Controller ◽  
Adaptive Lms ◽  
Adaptive Feedforward

This paper presents an adaptive feedforward control scheme using the least mean square (LMS) algorithm combined with sliding mode control for a flexible beam using piezoceramic actuator. A finite element model of the dynamic response of flexible beam system with PZT patches is derived and analyzed. Implementation of an adaptive LMS feedforward controller has the advantages of inherent stability and simplicity in design. The proposed adaptive LMS feedforward control system maintains the basic structure of the adaptive feedforward controller, but incorporates reference model in the system. Discrete sliding mode controller is added in the feedback loop to enhance the robustness of control system subjected to the variation of system parameters and external disturbances. Simulation results from flexible beam model verify the effectiveness of the proposed adaptive LMS feedforward with sliding mode control scheme and good disturbance rejection properties.

Control of coagulation process by dual wavelength article analyzer

1997 ◽  
Vol 36 (4) ◽  
pp. 135-142 ◽  
Author(s):  
Norihito Tambo ◽  
Yoshihiko Matsui ◽  
Ken-ichi Kurotani ◽  
Masakazu Kubota ◽  
Hirohide Akiyama ◽  
...  
Keyword(s):  
Water Quality ◽  
Control System ◽  
Predictive Control ◽  
Control Method ◽  
Feedforward Control ◽  
Raw Water ◽  
Floc Size ◽  
Coagulation Process ◽  
Series Of Experiments ◽  
Size Data

A coagulation process for water purification plants mainly uses feedforward control based on raw water quality and empirical data and requires operator's help. We developed a new floc sensor for measuring floc size in a flush mixer to be used for floc control. A control system using model predictive control was developed on the floc size data. A series of experiments was performed to confirm controllability of settled water quality by controlling flush mixer floc size. An automatic control with feedback from the coagulation process was evaluated as practical and reliable. Finally this new control method was applied for actual plant and evaluated as practical.

Feasibility Study of the Novel Nitrification Control System with Feedback and Auto Calibration Feedforward Control

2015 ◽  
Vol 2015 (2) ◽  
pp. 1-5
Author(s):  
Ichiro Yamanoi ◽  
Yoshinori Nishida ◽  
Nobuyuki Nakamura ◽  
Takeshi Takemoto ◽  
Kenji Toyooka ◽  
...  
Keyword(s):  
Control System ◽  
Feasibility Study ◽  
Feedforward Control ◽  
The Novel

High-Speed End Milling Using a Feedforward Control Architecture

1996 ◽  
Vol 118 (2) ◽  
pp. 178-187 ◽  
Author(s):  
E. D. Tung ◽  
M. Tomizuka ◽  
Y. Urushisaki
Keyword(s):  
High Speed ◽  
Feedforward Control ◽  
End Milling ◽  
Phase Error ◽  
Cutting Speed ◽  
Frequency Domain Analysis ◽  
Maximum Speed ◽  
Drive Control ◽  
Machining Errors ◽  
Feedforward Controller

Experiments are performed for end milling aluminum at 15,000 RPM spindle speed (1,508 m/min cutting speed) and up to 3 m/min table feedrate using an experimental machine tool control system. A digital feedforward controller for feed drive control incorporates the Zero Phase Error Tracking Controller (ZPETC) and feedforward friction compensation. The controller achieves near-perfect (±3 μm) tracking over a 26 mm trajectory with a maximum speed of 2 m/min. The maximum contouring error for a 26 mm diameter circle at this speed is less than 4 μm. Tracking and contouring experiments are conducted for table feedrates as high as 10 m/min. Frequency domain analysis demonstrates that the feedforward controller achieves a bandwidth of 10 Hz without phase distortion. In a direct comparison of accuracy, the machining errors in specimens produced by the experimental controller were up to 20 times smaller than the errors in specimens machined by an industrial CNC.

Waukesha Engine’s New 2 and 3 MWE High Performance, Ultra-Lean Engines and Enginators™ for the Worldwide 50Hz and 60Hz Power Generation Markets

2007 ◽  
Author(s):  
Corey A. Honl ◽  
Ryan M. Rudnitzki
Keyword(s):  
Power Generation ◽  
Control System ◽  
High Performance ◽  
Fuel Injection ◽  
Early Stage ◽  
Major Elements ◽  
Product Strategy ◽  
Product Lines ◽  
Stage Performance ◽  
High Level

The following paper describes the release of the 220GL engine and APG2000/3000 Enginator™ product lines from Waukesha Engine. The major elements of the release that will be covered include the installation and calibration of the ESM® control system, the development of new capabilities to control fuel injection and its associated features, the integration of Waukesha-introduced components on the 220GL, high-level product strategy and justification, and early stage performance figures from development testing.

scholarly journals Pressure Based Lift Estimation and its Application to Feedforward Load Control employing Trailing Edge Flaps

2020 ◽  
Author(s):  
Sirko Bartholomay ◽  
Tom T. B. Wester ◽  
Sebastian Perez-Becker ◽  
Simon Konze ◽  
Christian Menzel ◽  
...  
Keyword(s):  
Surface Pressure ◽  
Feedforward Control ◽  
Force Balance ◽  
Estimation Methods ◽  
Load Control ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Feedforward Controller ◽  
Trailing Edge Flap ◽  
C 30

Abstract. This experimental load control study presents results of an active trailing edge flap feedforward controller for wind turbine applications. The controller input is derived from pressure based lift estimation methods that rely either on a quasi-steady method, based on a three-hole probe, or on an unsteady method that is based on three selected surface pressure ports. Furthermore, a standard feedback controller, based on force balance measurements, is compared to the feedforward control. A Clark-Y airfoil is employed for the wing that is equipped with a trailing edge flap of x/c = 30 % chordwise extension. Inflow disturbances are created by a two-dimensional active grid. The Reynolds number is Re = 290,000 and reduced frequencies of k = 0.07 up to k = 0.32 are analyzed. Within the first part of the paper, the lift estimation methods are compared. The surface pressure based method shows generally more accurate results whereas the three-hole probe estimate overpredicts the lift amplitudes with increasing frequencies. Nonetheless, employing the latter as input to the feedforward controller is more promising as a beneficial phase lead is introduced by this method. A successful load alleviation was achieved up to reduced frequencies of k = 0.192.

Sign in / Sign up

Export Citation Format

Share Document