scholarly journals Bang-Bang Trajectory Plans With Dynamic Balance Constraints: Fast Rotational Reconfigurations for RoboSimian

2014 ◽  
Author(s):  
Katie Byl ◽  
Feodor Tobler
Keyword(s):  
Position Control ◽  
Center Of Pressure ◽  
Dynamic Balance ◽  
Safety Margin ◽  
High Impedance ◽  
Accurate Position ◽  
High Torque ◽  
Limited Base ◽  
Base Of Support ◽  
Joint Velocity

This paper investigates the problem of rapidly transitioning the pose of a limbed robot while remaining balanced. In particular, we consider motions where rotational accelerations may significantly affect the center of pressure location within a limited base of support. We consider solutions for high-impedance robots with stiff, high-torque actuators that essentially provide accurate, position-control outputs at the joints. We present and compare three methods for generating joint trajectories to achieve fast yet feasible dynamic motions for such systems while maintaining a safety margin for the center of pressure location, toward robust balance. We focus on development of theory and intuition for each method and quantify performance in terms of achievable speed of transition and required joint velocity limits.

Accurate Position Control for Hydraulic Servomechanisms

2019 ◽  
Author(s):  
Manuel Pencelli ◽  
Renzo Villa ◽  
Alfredo Argiolas ◽  
Gianni Ferretti ◽  
Marta Niccolini ◽  
...  
Keyword(s):  
Position Control ◽  
Accurate Position

scholarly journals Correction to: Accurate position control of shape memory alloy actuation using displacement feedback and self-sensing system

2021 ◽  
Author(s):  
Ermira Junita Abdullah ◽  
Josu Soriano ◽  
Iñaki Fernández de Bastida Garrido ◽  
Dayang Laila Abdul Majid
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Position Control ◽  
Sensing System ◽  
Accurate Position

scholarly journals Effects of white Gaussian noise on dynamic balance in healthy young adults

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ziyou Zhou ◽  
Can Wu ◽  
Zhen Hu ◽  
Yujuan Chai ◽  
Kai Chen ◽  
...  
Keyword(s):  
Young Adults ◽  
Gaussian Noise ◽  
Center Of Pressure ◽  
Dynamic Balance ◽  
White Gaussian Noise ◽  
Fluctuation Analysis ◽  
Balance Performance ◽  
Short Term ◽  
Crossover Point ◽  
Short Time

AbstractIt has been known that short-time auditory stimulation can contribute to the improvement of the balancing ability of the human body. The present study aims to explore the effects of white Gaussian noise (WGN) of different intensities and frequencies on dynamic balance performance in healthy young adults. A total of 20 healthy young participants were asked to stand at a dynamic balance force platform, which swung along the x-axis with an amplitude of ± 4° and frequency of 1 Hz. Their center of pressure (COP) trajectories were recorded when they were stimulated by WGN of different intensities (block 1) and different frequencies (block 2). A traditional method and detrended fluctuation analysis (DFA) were used for data preprocessing. The authors found that only with 75–85 dB WGN, the COP parameters improved. WGN frequency did not affect the dynamic balance performance of all the participants. The DFA results indicated stimulation with 75 dB WGN enhanced the short-term index and reduced the crossover point. Stimulation with 500 Hz and 2500 Hz WGN significantly enhanced the short-term index. These results suggest that 75 dB WGN and 500 Hz and 2500 Hz WGN improved the participants’ dynamic balance performance. The results of this study indicate that a certain intensity of WGN is indispensable to achieve a remarkable improvement in dynamic balance. The DFA results suggest that WGN only affected the short-term persistence, indicating the potential of WGN being considered as an adjuvant therapy in low-speed rehabilitation training.

Center of Pressure Trajectory and Spatiotemporal Gait Parameters When Walking with Limited Knee Flexion

2021 ◽  
Vol 65 (1) ◽  
pp. 1490-1493
Author(s):  
Seobin Choi ◽  
Jieon Lee ◽  
Gwanseob Shin
Keyword(s):  
Knee Flexion ◽  
Stance Phase ◽  
Center Of Pressure ◽  
Dynamic Balance ◽  
Left Knee ◽  
Step Width ◽  
Normal Walking ◽  
Gait Stability ◽  
Gait Parameters ◽  
Stiff Knee

Stiff-knee, which indicates reduced range of knee flexion, may decrease gait stability. Although it is closely related to an increase in fall risk, the effect of limited knee flexion on the balance capacity during walking has not been well studied. This study aimed at examining how walking with limited knee flexion would influence the center of pressure (COP) trajectory and spatiotemporal gait parameters. Sixteen healthy young participants conducted four different walking conditions: normal walking and walking with limited knee flexion of their left knee up to 40 and 20 degrees, respectively. Results show that the participants walked significantly (p<0.05) slower with shorter stride length, wider step width, less cadence, and decreased stance phase when walking with limited knee flexion, compared to normal walking. The increase in the asymmetry and variability of the COP was also observed. It indicates that limited knee flexion during walking might affect the dynamic balance.

Experimental Investigation Into Improved Wrapper Control of Hot Strip Steel Rolling Mill Downcoilers

2009 ◽  
Author(s):  
D. Ll. Davies ◽  
J. Watton ◽  
Y. Xue ◽  
G. A. Williams
Keyword(s):  
Rolling Mill ◽  
New Technologies ◽  
Position Control ◽  
Steel Production ◽  
Rolling Process ◽  
Steel Rolling ◽  
Hot Strip ◽  
Accurate Position ◽  
Manufacturing Techniques ◽  
Coiling Process

With increasing international competition in steel production mainly from developing nations, it is important for steel plants to keep up to date with new technologies, and continuously improve on current practices and manufacturing techniques to remain competitive. This paper looks specifically at improvements to the hot rolling mill downcoilers, which is where the strip is coiled at the end of the rolling process. Hydraulic and pneumatic technology is combined to give accurate position control of guide wrappers that aid the initial coiling process. The paper presents an experimental test rig, using an actual wrapper guide, constructed to evaluate the specific design approach.

scholarly journals Research on position offset compensation of underwater manipulator

2021 ◽  
Vol 2125 (1) ◽  
pp. 012008
Author(s):  
Shanbin Ren ◽  
Hui Zhang ◽  
Kai Li ◽  
Yujun Cheng ◽  
Xin Liu ◽  
...  
Keyword(s):  
Curve Fitting ◽  
Position Control ◽  
Kinematic Model ◽  
Compensation Method ◽  
Ansys Analysis ◽  
Underwater Manipulator ◽  
Accurate Position ◽  
Offset Compensation

Abstract A compensation method for end position offset of underwater manipulator is presented in this paper. Firstly, the end deformation of the underwater manipulator is obtained by ANSYS analysis, and then the end position offset equation is obtained by MATLAB curve fitting. Finally, the equation is added to the kinematic model of the underwater manipulator, which improves the accuracy of the kinematic model of the underwater manipulator and lays a foundation for the accurate position control of the underwater manipulator.

Accurate Position Control of a Pneumatic Actuator

1990 ◽  
Vol 112 (4) ◽  
pp. 734-739 ◽  
Author(s):  
Jiing-Yih Lai ◽  
Chia-Hsiang Menq ◽  
Rajendra Singh
Keyword(s):  
Control Strategy ◽  
Pulse Width Modulation ◽  
Position Control ◽  
Integral Control ◽  
Pneumatic Actuators ◽  
Actuator Dynamics ◽  
Position Accuracy ◽  
Modulation Mode ◽  
Nonlinear Mechanical ◽  
Accurate Position

We propose a new control strategy for on-off valve controlled pneumatic actuators and robots with focus on the position accuracy. A mathematical model incorporating pneumatic process nonlinearities and nonlinear mechanical friction has been developed to characterize the actuator dynamics; this model with a few simplifications is then used to design the controller. In our control scheme, one valve is held open and the other is operated under the pulse width modulation mode to simulate the proportional control. An inner loop utilizing proportional-plus-integral control is formed to control the actuator pressure, and an outer loop with displacement and velocity feedbacks is used to control the load displacement. Also, a two staged feedforward force is implemented to reduce the steady state error due to the nonlinear mechanical friction. Experimental results on a single-degree-of-freedom pneumatic robot indicate that the proposed control system is better than the conventional on-off control strategy as it is effective in achieving the desired position accuracy without using any mechanical stops in the actuator.

Dynamic Leap and Balance Test: Ability to Discriminate Balance Deficits in Individuals With Chronic Ankle Instability

2020 ◽  
Vol 29 (3) ◽  
pp. 263-270 ◽  
Author(s):  
Abbis H. Jaffri ◽  
Thomas M. Newman ◽  
Brent I. Smith ◽  
Giampietro L. Vairo ◽  
Craig R. Denegar ◽  
...  
Keyword(s):  
Dynamic Stability ◽  
Healthy Subjects ◽  
Ankle Instability ◽  
Dynamic Balance ◽  
Chronic Ankle Instability ◽  
Assessment Tools ◽  
Balance Test ◽  
Balance Task ◽  
History Of ◽  
Base Of Support

Context: The Dynamic Leap Balance Test (DLBT) is a new dynamic balance task that requires serial changes in base of support with alternating limb support and recovery of dynamic stability, as compared with the Y modification of the Star Excursion Balance Test (Y-SEBT), which assesses dynamic stability over an unchanging base of support. Objectives: To assess the dynamic balance performance in 2 different types of dynamic balance tasks, the DLBT and the SEBT, in subjects with unilateral chronic ankle instability (CAI) when compared with matched controls. The authors hypothesized that the DLBT score would significantly differ between the CAI involved and uninvolved limbs (contralateral and healthy matched) and demonstrate a modest (r = .50) association with the SEBT scores. Design: Case-control. Setting: Controlled laboratory. Participants: A total of 36 physically active adults, 18 with history of unilateral CAI and 18 without history of ankle injury, were enrolled in the study. CAI subjects were identified using the Identification of Functional Ankle Instability questionnaire. Interventions: The DLBT and the SEBT were performed in a randomized order on a randomly selected limb in CAI and healthy subjects. Main Outcome Measures: Time taken to complete the DLBT and the reach distances performed on the SEBT were compared between the CAI and the healthy subjects. Results: There were no statistically significant differences (P < .05) in SEBT reach distances between groups. The DLBT time was greater (P < .01) for unstable ankles compared with the stable ankle. The authors found no correlation (P > .05) between DLBT time and any of the SEBT reach distances suggesting that the DLBT provides unique information in the assessment of patients with CAI. Conclusion: The DLBT challenges the ability to maintain postural control in CAI subjects differently than the SEBT. There is a need of more dynamic balance assessment tools that are functional and clinically relevant.

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