Dynamic Response Analyses of Rabbit Knee Joint

1999 ◽  
Author(s):  
M. Kasra ◽  
M. D. Grynpas ◽  
A. Shirazi-Adl

Abstract The knee joint is a complex nonlinear dynamic system. It is generally known that mechanical factors play an important role in the etiology of knee injuries and diseases such as osteoarthritis. While performing daily activities such as walking, running, and climbing as well as during occupational operations, the joint is exposed to vibrations and multiple impacts. During these activities, according to an individual’s condition (e.g., age, fitness, weight), the joint load and stiffness may reach critical limits initiating or accelerating different knee disorders. This is the case in athletes or workers during occupational activities (1). Therefore, understanding the dynamic characteristics of the knee joint is essential in prediction and prevention of knee disorders as well as in subsequent joint replacement and rehabilitation procedures. There have been very few reported experimental studies investigating the dynamic behavior of the whole knee joint as a dynamic system (2). The objective of this study was to investigate the changes in mechanical properties of the rabbit knee joint under different compressive dynamic loading conditions. Rabbit has frequently been used as an osteoarthritic knee model (3). The data obtained in this study, hence, will also be beneficial in our future studies of osteoarthritic rabbit models.

2021 ◽  
pp. 26-41
Author(s):  
Yu. Romasevych ◽  
◽  
V. Loveikin ◽  
A. Shevchuk ◽  
I. Bolbot ◽  
...  

In the article, experimental studies of the neurocontroller of a laboratory installation of a quadrocopter link are presented. The latter is a nonlinear dynamic system. The input vector of the neurocontroller included the angle of inclination of the rod (a beam of the quadcopter) relative to the horizon, its angular velocity, and the angular velocity of the propeller. The output signal of the neurocontroller is proportional to the supply voltage of the propeller drive. In the article, the planning of experimental studies was carried out and eight indicators were selected, according to which the quality of the control process was evaluated. In addition, a qualitative analysis of the control process of the dynamic system motion was carried out with the corresponding graphical dependencies. The data obtained showed a good quality of control at a zero setpoint angle. For other values of the setpoint (-0.52 and -1.05 rad), the neurocontroller provides the rod aboutness to the setpoint angle and the control stability. However, the quality of control is not high. The reason for this effect has been established in the work. In order to improve the quality of control, the neurocontroller was modified by including an integral component in its structure. At the same time, the steady-state control error has significantly decreased with minor changes in other estimated indicators.


1987 ◽  
Vol 16 (1) ◽  
pp. 121-129
Author(s):  
M. Möttönen ◽  
M. Pantio ◽  
T. Nevalainen

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