In vivo validation of a computational bone adaptation model using open-loop control and time-lapsed micro-computed tomography

Abstract The role of mechanical loading in trabecular bone adaptation is important for the understanding of bone integrity in different loading scenarios such as microgravity and for the etiology of age-related bone fractures. There have been numerous in vivo animal studies of bone adaptation, most of which are related to cortical bone remodeling, aimed at the investigation of Wolff’s Law [4], An interesting experimental model for trabecular bone adaptation has been developed in the rat tail vertebrae [2,3]. This model is attractive for trabecular bone adaptation studies because a controlled mechanical load can be applied to a whole vertebra with minimal surgical trauma, using a relatively inexpensive animal model. In addition, with advanced micro computed tomography (micro-CT) or micro magnetic resonance imaging (micro-MRI) coupled with large scale finite element modeling techniques, it is possible to characterize the three-dimensional (3D) stress/strain environment in the bone tissue close to a cellular level (∼25μm) [1]. Therefore, this in vivo rat tail model has a tremendous potential for quantification of the relationship between mechanical stimulation and biological response in trabecular bone adaptation.

Download Full-text

Responses and Optimization of a PID-Based Speed Regulating System of the Planetary Mixer

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.418-420.1865 ◽

2011 ◽

Vol 418-420 ◽

pp. 1865-1868

Author(s):

Ming Jin Yang ◽

Xi Wen Li ◽

Zhi Gang Wang ◽

Tie Lin Shi

Keyword(s):

Control System ◽

Open Loop ◽

Open Loop Control ◽

Efficient Operation ◽

Loop Control ◽

Loop Control System ◽

Response Optimization ◽

Close Loop Control ◽

Close Loop Control System

The performance of speed regulating is very important to the mixing process with safe, efficient operation and high quality of production. Strategies and practices of responses and optimization of a PID-based speed regulating system of a planetary mixer were presented in this paper. Research results show that: by means of the signal constraint function presented by Simulink Response Optimization, optimization PID parameters of the 2-DOF-PID controller can be obtained, and the response of close-loop control system has quite good performance of overshoot, response time, and stability compared with an open-loop control system.

Download Full-text

Experimental Verification of Open-loop Control for an Underwater Eel-like Robot

The International Journal of Robotics Research ◽

10.1177/0278364902021010095 ◽

2002 ◽

Vol 21 (10-11) ◽

pp. 849-859 ◽

Cited By ~ 17

Author(s):

Kenneth A. Mcisaac ◽

James P. Ostrowski

Keyword(s):

Experimental Work ◽

Experimental Verification ◽

Vision System ◽

Open Loop ◽

Open Loop Control ◽

Loop Control ◽

Position Sensing ◽

Theoretical Predictions ◽

Approximate Expressions ◽

Good Agreement

In this paper, we describe experimental work using an underwater, biomimetic, eel-like robot to verify a simplified dynamic model and open-loop control routines. We compare experimental results to previous analytically derived, but approximate expressions for proposed gaits for forward/backward swimming, circular swimming, sideways swimming and turning in place. We have developed a five-link, underwater eel-like robot, focusing on modularity, reliability and rapid prototyping, to verify our theoretical predictions. Results from open-loop experiments performed with this robot in an aquatic environment using an off-line vision system for position sensing show good agreement with theory.

Download Full-text