The formation principle of 3-D cutting elliptical trajectory was analysed and a prediction model of tool wear was established in the present work. Besides, a self-developed three-dimensional elliptical vibration device was employed to conduct turning experiment. Compared with the proposed model, the experimental results showed a great agreement with the proposed prediction model. This work may provide a reference for the further optimization of the 3-D elliptical vibration cutting parameters.
During the mode experiments of the FCRM, we find that the mode characteristics of the FCRM change with the different tip mass. As the direct drive source of the FCRM, the output of the motor also have great influences on the dynamic characteristics of the FCRM. Thus, the nonlinear modelling and dynamic stability of a FCRM with base disturbance and terminal load are analyzed in this paper. During the analysis process, the methods of mechanism modeling and numerical calculation are adopted.
This paper presents the complete dynamic model of a new six degrees of freedom (DOF) spatial 3-RPRS parallel manipulator. Further, a robust task-space trajectory tracking control is also designed for the manipulator along with a nonlinear disturbance observer. To demonstrate the efficacy and show the complete performance of the proposed controller, virtual prototype experiments are executed using one of multibody dynamics software namely MSC Adams.
Compared to the traditional pHRI measurement approaches, the proposed method arranged the sensors in the mechanical joint instead of the connection cuff. This kind of architecture has compact architecture and improves the wearing comfort, which can adapt to various operators and is convenient to be applied in the wearable exoskeleton. The performance of the DEM will be studied in the following work and human-exoskeleton coordination control strategies will be investigated in future work.
In our study, our aim was biomechanically to investigate the effectiveness of Pertrochanteric Fixators (PTFs) applied with two different configurations of schanz screws inserted to the femoral head in ITFs.
An alternative design method of the double-layer combined die using autofrettage theory is proposed. The relationship between the autofrettage pressure and the yield radius of the die insert is obtained, and expressions of residual stresses and displacements, which are directly related to geometric parameters, material properties and internal pressure, are derived. Compared with the conventional combined die, the autofrettaged die can bear larger working pressure, as expected.
A dynamic thermal-mechanical model of the spindle-bearing system is proposed to investigate the transient thermal characteristics. A spindle-bearing system with adjustable and measurable preload is designed and constructed. Validated by the experiments, thermal feedbacks on boundary conditions and thermal contact conductance are non-ignorable for the accurate simulation. The proposed model could also be generalized in other mechanical systems to improve the prediction accuracy.
This work investigates the effect of electrode geometry on flushing capability and debris removal efficiency in Electrical Discharge Drilling process. Drilling operations on stainless steel 304 were performed using circular and side-cut electrodes. Experimental results were compared with respect to drilling performance as well as dimensional accuracy and surface quality of drilled holes. Three-phase three-dimensional CFD models were also developed to analyze the flow field at interelectrode gap.
Buckling of nonuniform carbon nanotubes are studied under concentrated and distributed axial loads. Solution is obtained via weak formulation and Rayleigh-Ritz method for a combination of simply supported, clamped and free boundary conditions for uniformly and triangularly distributed axial loads. Buckling load under tip load is more sensitive to the change in the cross-section. However buckling load is more sensitive to the magnitude of the tip load for the clamped-free boundary conditions.
A new exoskeleton for human gait motion assistance and rehabilitation is proposed, to investigate motion capabilities and feasibility. Human gait analysis on healthy and disabled subjects is performed to obtain references motion laws for normal gait. A dynamic simulation model of exoskeleton is achieved in ADAMS computational environment. The exoskeleton prototype motion laws, resulted from motion analysis based on ultra speed video cameras are compared with human subject motion laws.
Force sensing plays an important role in minimally invasive surgery. In this study, a new asymmetric cable-driven type of micromanipulator for a surgical robot was designed, and a joint angle estimator(JAE) was designed based on the dynamical model system. Closed-loop control of the joint angle was carried out by regarding the JAE output as the feedback signal. An external force estimator was designed using a disturbance observer. The experimental results shown the correctness and validity.
The design of these devices involves the human body as a support environment. Based on this premise, the development of wearable devices requires an improved understanding of the skin strain field of the body segment during human motion. This paper presents a new methodology to improve and optimize the design of wearable devices, specifically orthoses, based on the combination of biomechanical studies, computer aided design/computer aided engineering (CAD/CAE) tools and 3D printing technology.
In the present paper, we investigate a modified pseudo-rigid-body (MPRB) modeling approach for compliant mechanisms with fixed-guided beam flexures by considering the load-dependent property. The proposed MPRB model provides a more analytical and accurate method to predict the performance characteristics such as deformation capability, stiffness variation, as well as error motions of complaint mechanisms and offers a new look into the design and optimization of beam-based compliant mechanisms.
In this paper, oriented to the additive manufacturing technology, a skew line gear pair, whose number of the line tooth of the driving line gear is 1, is designed to improve its strength and overall stiffness, to reduce its volume and manufacturing cost.This paper provides a basic theory for the skew line gear pair applied in conventional powered transmission field.