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Modeling and Control of a New Spherical Robot with Cable Transmission
Lufeng Zhang,Xuemei Ren,Dongdong Zheng 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.3
This paper presents a new spherical robot with a cable transmission mechanism. Cable transmission mechanism replaces conventional gear train to eliminate the influence of gear backlash, reduce the robot mass, lower the costs on mechanical customization and can be arranged flexibly. By projection method, the 3D robot dynamic model with structural asymmetry is decoupled into balance subsystem and velocity subsystem, and the kinetics equations are established based on Newton-Euler’s law. For the balance control, an adaptive law is designed to estimate the upper bound instead of the exact value of the uncertainty caused by the structural asymmetry online firstly, then a finite-time adaptive hierarchical sliding mode control (FAHSMC) strategy is proposed based on the estimation result to minimize the convergence time. For the velocity control, a hierarchical sliding mode controller (HSMC) and a tracking differentiator (TD)-based nonlinear disturbance observer are designed, leading to enhanced disturbance rejection capability and a reduced steady-state error. Simulations and experiments on a real spherical robot are conducted to demonstrate the efficacy of the proposed control strategies.
Tobiasova, Zuzana,Zhang, Lufeng,Yi, Tai,Qin, Linfeng,Manes, Thomas D.,Kulkarni, Sanjay,Lorber, Marc I.,Rodriguez, Frederick C.,Choi, Je-Min,Tellides, George,Pober, Jordan S.,Kawikova, Ivana,Bothwell, Ovid Technologies Wolters Kluwer -American Heart A 2011 CIRCULATION - Vol.124 No.2
<P>Ligands activating the transcription factor peroxisome proliferator-activated receptor-γ (PPARγ) have antiinflammatory effects. Vascular rejection induced by allogeneic T cells can be responsible for acute and chronic graft loss. Studies in rodents suggest that PPARγ agonists may inhibit graft vascular rejection, but human T-cell responses to allogeneic vascular cells differ from those in rodents, and the effects of PPARγ in human transplantation are unknown.</P>
Chen Haijun,Guo Tengteng,Zhang Lufeng 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4
Five-phase fractional slot concentrated winding permanent magnet (FSCWPM) machine with equal/unequal stator teeth can improve the torque density by added third harmonic current injection (Sin + 3rd). However, the injection of the third harmonic current will change the stator, rotor, and PM losses, and thus the thermal distribution. Therefore, it is necessary to conduct a comparative study on the losses and the thermal performances of the fi ve-phase FSCWPM machine with the sine current supply and Sin + 3rd current supply. In this paper, the structures of the fi ve-phase FSCWPM machines with equal/ unequal stator teeth are illustrated, and their losses characteristic at diff erent rotating speeds including copper loss, PM loss, and iron-core loss are comparatively analyzed under the same output torque constraint. Then, their thermal distributions are investigated based on the coupling of electromagnetic-thermal calculation of the 3D fi nite element (FE) method. The results demonstrate that the fi ve-phase FSCWPM machines energized with the Sin + 3rd current have a better thermal performance at a low rotating speed, especially the fi ve-phase FSCWPM machine with unequal stator teeth. Furthermore, the thermal experiment concerning a fi ve-phase FSCWPM machine with unequal stator teeth is conducted to verify the validity of the related analysis.