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Your search keyword '"Hua, Zhichao"' showing total 32 results
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32 results on '"Hua, Zhichao"'

9. Magnetic-Free Wireless Self-Direct Drive Motor System for Biomedical Applications With High-Robustness

Author

Xue, Zhiwei, Chau, Kwok Tong, Liu, Wei, and Hua, Zhichao

Abstract

The integration of high-precision robotics and magnetic resonance imaging (MRI) exhibits the potential to enhance the accuracy and safety of MRI image-guided surgery. However, the potential hazards associated with conventional electromagnetic servomotors in strong magnetic fields have hindered the development of MRI-compatible robotics. To address this issue, this article proposes and implements a novel magnetic-free wireless drive system that creatively integrates capacitive power transfer with ultrasonic motors to realize the truly wireless self-direct drive without strong magnetic field interference. The proposed system overcomes the drawbacks of existing wireless motors requiring microcontrollers, power switches and communication modules at the motor side, facilitating high-degree integration and maintenance-free operation. In addition, a dual-mode wireless drive control scheme is proposed to achieve the full-speed range wireless direct drive. Promisingly, the proposed system is unaffected by coupling mechanism misalignment and load variation, ensuring precise manipulation with high robustness. Both theoretical analysis and experimental results are conducted to verify the effectiveness of the proposed wireless motor system.

Published
2024
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12. Dynamic Wireless Charging for Electric Vehicles With Autonomous Frequency Control

Author

Hua, Zhichao, Chau, K. T., Pang, Hongliang, and Yang, Tengbo

Abstract

This article proposes a dynamic wireless charging scheme for electric vehicles (EVs) using autonomous frequency control. The key is to make the receiver circuit of an EV always operate in the splitting region by adopting proper transmitter coils and displacement between adjacent transmitter coils. Then, by sensing the primary current, the autonomous frequency control can achieve constant charging power in the splitting region even the EV is moving. The operating frequency of the system is monitored online. When the operating frequency indicates that the EV is leaving the current transmitter coil and approaching the next transmitter coil, the current transmitter circuit stops working and the next transmitter circuit starts to work, thus achieving continuous charging on the road. Both theoretical calculations and experimental results are given to validate the feasibility of the proposed scheme.

Published
2023
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26. Colony: A Privileged Trusted Execution Environment With Extensibility.

Author

Xia, Yubin, Hua, Zhichao, Yu, Yang, Gu, Jinyu, Chen, Haibo, Zang, Binyu, and Guan, Haibing

Subjects
*SYSTEMS software, *COLONIES, *BURGLARY protection, *CONFERENCE papers, *SEMANTICS, *BEE colonies
Abstract

The code base of system software is growing fast, which results in a large number of vulnerabilities: for example, 296 CVEs have been found in Xen hypervisor and 2195 CVEs in Linux kernel. To reduce the reliance on the trust of system software, many researchers try to provide trusted execution environments (TEEs), which can be categorized into two types: non-privileged TEEs and privileged TEEs. Non-privileged TEEs (e.g., Intel SGX) are extensible, but cannot protect security services like virtual machine introspection (VMI) due to the lack of system-level semantics. On the contrary, privileged TEEs (e.g., the secure world of ARM TrustZone) have system-level semantics, but any additional service implemented in the privileged TEE directly increases the TCB of the entire system. In this article, we propose a new design of TEE to support system-level security services and achieve better extensibility with a small TCB. Each TEE instance of the proposed design is named a Colony. Specifically, we introduce a secure monitor for isolation and capability management. Each Colony is assigned capabilities to access only necessary system-level semantics. We use the new TEE to build four security services, including secure device accessing, VMI tools, a system call tracer, and a much more complex service to virtualize ARM TrustZone with multiple Colonies. We have implemented the system on ARMv7 and ARMv8 platforms, in Xen hypervisor and Linux kernel, and perform a detailed evaluation to show its efficiency. 1. This paper is an extended version of the conference paper published in USENIX Security’17: vTZ: Virtualizing ARM TrustZone. A brief summary of differences is in Section. [ABSTRACT FROM AUTHOR]

Published
2022
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28. XPC

Author

Du, Dong, primary, Hua, Zhichao, additional, Xia, Yubin, additional, Zang, Binyu, additional, and Chen, Haibo, additional

Published
2019
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