scholarly journals Biped Walking Based on Stiffness Optimization and Hierarchical Quadratic Programming

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1696
Author(s):  
Xuanyang Shi ◽  
Junyao Gao ◽  
Yizhou Lu ◽  
Dingkui Tian ◽  
Yi Liu
Keyword(s):  
Quadratic Programming ◽  
Real Time ◽  
Inverse Dynamics ◽  
Reaction Force ◽  
Feedback Controller ◽  
Whole Body ◽  
Real Time Control ◽  
Velocity Feedback ◽  
Landing Point ◽  
Multiple Variables

The spring-loaded inverted pendulum model is similar to human walking in terms of the center of mass (CoM) trajectory and the ground reaction force. It is thus widely used in humanoid robot motion planning. A method that uses a velocity feedback controller to adjust the landing point of a robot leg is inaccurate in the presence of disturbances and a nonlinear optimization method with multiple variables is complicated and thus unsuitable for real-time control. In this paper, to achieve real-time optimization, a CoM-velocity feedback controller is used to calculate the virtual landing point. We construct a touchdown return map based on a virtual landing point and use nonlinear least squares to optimize spring stiffness. For robot whole-body control, hierarchical quadratic programming optimization is used to achieve strict task priority. The dynamic equation is given the highest priority and inverse dynamics are directly used to solve it, reducing the number of optimizations. Simulation and experimental results show that a force-controlled biped robot with the proposed method can stably walk on unknown uneven ground with a maximum obstacle height of 5 cm. The robot can recover from a 5 Nm disturbance during walking without falling.

scholarly journals Compliant Humanoids Moving Toward Rehabilitation Applications: Transparent Integration of Real-Time Control, Whole-Body Motion Generation, and Virtual Reality

2019 ◽  
Vol 26 (4) ◽  
pp. 83-93
Author(s):  
Pouya Mohammadi ◽  
Enrico Mingo Hoffman ◽  
Niels Dehio ◽  
Milad S. Malekzadeh ◽  
Martin Giese ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Real Time ◽  
Body Motion ◽  
Whole Body ◽  
Motion Generation ◽  
Real Time Control ◽  
Time Control

The Optimal Locus Approach With Machining Applications

1989 ◽  
Vol 111 (2) ◽  
pp. 260-267 ◽  
Author(s):  
Yoram Koren
Keyword(s):  
Real Time ◽  
Real Time Control ◽  
Machining Processes ◽  
Mathematical Basis ◽  
Control Loops ◽  
Time Control ◽  
Multiple Variables ◽  
Optimization Methodology ◽  
And Control ◽  
Grinding System

An optimal locus concept is introduced as the basis for an optimization methodology for real-time control subject to time-varying constraints. The optimal locus in the control plane contains all possible optimum points, and the actual point is found at the intersection of the optimal locus with the most limiting constraint. The mathematical basis of the approach is a given set of equations which is less than the number of unknowns, and the addition of real-time measurements to compensate for the missing information. The control system generates the optimal parameters in real time, and uses them as references to the control loops. The optimization methodology and control architecture are structures in a generalized way for application to processes having multiple variables and subject to several constraints. The proposed controller architecture can effectively control many machining processes. The optimal locus approach was applied to a grinding system and the experimental results verify the proposed theory.

Improving the Performance of a Vibration Neutraliser by Controlling Its Stiffness and Damping

2000 ◽  
Author(s):  
M. J. Brennan ◽  
M. R. F. Kidner
Keyword(s):  
Experimental Study ◽  
Fuzzy Logic ◽  
Real Time ◽  
Fuzzy Logic Controller ◽  
Feedback System ◽  
Real Time Control ◽  
Velocity Feedback ◽  
Time Control ◽  
Operational Frequency ◽  
Stiffness And Damping

Abstract This paper is concerned with improving the performance of a vibration neutraliser (absorber) by making it adaptive. To achieve this, the stiffness and damping of the device has to be controlled so that the impedance of the neutraliser is optimised at its operational frequency. The results of an experimental study are presented where real-time control of such a device is demonstrated. The stiffness is adjusted by changing the geometry, and damping is controlled with a velocity feedback system. Both these actions are achieved using a fuzzy logic controller.

A Real Time Control Architecture for Continuously Managing Patients in a Care Unit

1995 ◽  
Vol 34 (05) ◽  
pp. 475-488
Author(s):  
B. Seroussi ◽  
J. F. Boisvieux ◽  
V. Morice
Keyword(s):  
Real Time ◽  
Linear Time ◽  
Treatment Plan ◽  
Control Architecture ◽  
Real Time Control ◽  
Time Representation ◽  
Time Control ◽  
Continuous Support ◽  
Definition Of ◽  
Computerized System

Abstract:The monitoring and treatment of patients in a care unit is a complex task in which even the most experienced clinicians can make errors. A hemato-oncology department in which patients undergo chemotherapy asked for a computerized system able to provide intelligent and continuous support in this task. One issue in building such a system is the definition of a control architecture able to manage, in real time, a treatment plan containing prescriptions and protocols in which temporal constraints are expressed in various ways, that is, which supervises the treatment, including controlling the timely execution of prescriptions and suggesting modifications to the plan according to the patient’s evolving condition. The system to solve these issues, called SEPIA, has to manage the dynamic, processes involved in patient care. Its role is to generate, in real time, commands for the patient’s care (execution of tests, administration of drugs) from a plan, and to monitor the patient’s state so that it may propose actions updating the plan. The necessity of an explicit time representation is shown. We propose using a linear time structure towards the past, with precise and absolute dates, open towards the future, and with imprecise and relative dates. Temporal relative scales are introduced to facilitate knowledge representation and access.

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