Lei Zhou

Lei Zhou

Ph.D. Candidate
Precision Motion Control Laboratory
Department of Mechanical Engineering
Massachusetts Institue of Technology
Address: 77 Mass. Ave., 35-030, Cambridge, MA, 02139
Email: leizhou AT mit DOT edu
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Welcome to my website!

I am PhD Candidate in the Department of Mechanical Engineering at MIT, under the supervision of Professor David L. Trumper. I am fortunate to have Professor Alexander H. Slocum, Professor Jeffery H. Lang, and Professor James L. Kirtley Jr. on my thesis committee together with my advisor.

My research interest focuses on the design and control for mechatronics systems, with an emphasis on electromagnetic actuators and sensors design, precision machines, control and estimation for motion systems, magnetic levitation, and manufacturing systems.

Before joining MIT, I earned my Bachelor's degree from the Dept. of Precision Instrument and Mechanology at Tsinghua University, Beijing, China.

I am interested in building high performance mechatronic systems through design and optimizations at all levels of the machine architecture, including modeling, machine design, electromagnetic design, electronics, instrumentation, control and estimation algorithm, etc.

Project Summary

Magnetically Suspended Reaction Sphere with One-axis Hysteresis Drive (1D-MSRS)

This project focuses on the design, modeling, and testing of a magnetically suspended reaction sphere driven by an one-axis hysteresis motor (1D-MSRS). The goal of this work is twofold: (a) exploring the possible design of a magnetically suspended reaction sphere driven about three-axes for spacecraft's attitude control; and (b) evaluating the performance of a hysteresis motor for the reaction wheel/sphere application. The novel 1D-MSRS demonstrates a hysteresis motor with a solid steel spherical rotor, which is magnetically suspended in all translational directions by a combination of an electromagnetic actuator and a bearingless motor. Modeling of the sphere’s magnetic suspension is demonstrated, and its motor dynamics is analyzed by an equivalent circuit model. This study also demonstrated that the hysteresis motor has a good potential for being used for high speed, low vibration reaction wheels.

Induction Motor Sensorless Estimation for Bandwidth Improvement

In the induction motor speed sensorless control, the bandwidth of the speed control loop is mainly limited by the convergence rate of the state estimation, especially the speed estimation. In order to improve the motor's speed tracking bandwidth and therefore allowing them being used in applications where the dynamic performance is critical, new state estimation schemes are needed. In this project, we first studied the application of the Moving Horizon Estimation (MHE) for induction motor state estimation. To improve the estimator's robustness with respect to the model parametric uncertainties, we designed a dual-stage adaptive MHE to estimate the parameters and the states simultaneously.

We also studied improvements towards the full-order adaptive observer for induction motors. In order to provide a better balance between the fundamental trade-off between bandwidth and noise in the speed estimation, we proposes a new speed estimation method with non-linear adaptation gain and feedforward terms. An iterative tuning method is used to automatically tune the feedforward gains for the speed estimation online. Experiments show that compared with the baseline adaptive estimation approach, the proposed method can demonstrate a 20x bandwidth improvement. Poster: [ Link].

This project is in colabration with Dr. Yebin Wang at Mitsubishi Electric Research Laboratories.

Concentrated Solar Power on Demand (CSPonD)

This project targeting at design and further deliver a set of design rule for an advanced thermal energy storage (TES) system directly charged by concentrated solar power (CSP). In the system, the concentrated beam enters directly into the molten salt TES vessel where it is absorbed and stored as sensible heat by the molten salt through the depth; hence the molten salt tank simultaneously acts as a volumetric receiver and a thermal energy storage system. We call this novel concept Concentrated Solar Power on Demand (CSPonD). One major feature of this system is the concept of virtual two-tank: using a loose-fitting horizontal moving raft (divider plate) in the vessel to separate hot and cold salt, and therefore making a more efficient thermocline than other similar designs. My research in this project focuses on the control of the temperature and flow field in the tank, and the design and control for the divider plate.

This project is led by Prof. Alexander H. Slocum, and is collaborating with Department of Nuclear Engineering at MIT and Masdar Institute of Science and Technology at UAE.

FlexLab and LevLab: A Portable Lab for Mechatronics Teaching

Flexlab/LevLab is an educational mechatronic system for control and mechatronics teaching in the Department of Mechanical Engineering at MIT. The FlexLab is a system of flexible cantilever beam with permanent magnets attached to it, while the LevLab demonstrates a magnetic suspension system, in which a spherical permanent magnet is magnetically levitated. Linear power amplifiers are used to energize the actuator coils, and Hall effect sensors are used to measure the position of the permanent magnet. Both labs are implemented on one printed circuit board, with actuators, sensors, and power amplifiers arranged on it. This system works together with myRIO from National Instruments, and the real-time controller is implemented in the myRIO. The system is designed to be portable, which allow students to work on experiments outside of the laboratory, and thus making better use of the time in lab. The design file of the Flexlab/LevLab is open source at here:

  • LabVIEW project for FlexLab and LevLab.
  • PCB design file and gerber file.

  • Videos

    Magnetic Suspended Reaction Sphere with One-axis Hysteresis Motor

    FlexLab and LevLab: A Portable Lab for Mechatronics Teaching

  • Journal Papers
  • Conference Proceedings
  • In Preparation
  • Patents
  • Thesis
  • Here is a list of my teaching/mentoring experiences:

  • Selected Course Projects

  • Courseworks at MIT
  • Hobbies

    In my spare time, I enjoy drawing and painting, reading fictions, and running. Here are some of my drawing/paintings :-)

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