Zhenbo Li

Relative Localization Method of Multiple Micro Robots Based on Simple Sensors

This paper presents a simple relative positioning algorithm for multiple micro robots. The micro robot is designed as a differential driven vehicle and actuated by MEMS-based electromagnetic micromotors. A simple relative positioning approach based only on one infrared emitter, receiver and compass is presented. Using this method, we characterized the accuracy of positioning between robots and identified sources of imprecision. Finally, this module is clearly demonstrated with the autonomous docking of multiple micro robots. The ability of our algorithm makes it cost effective and easy to deploy its application to multiple micro robots.

Unambiguous BOC Modulated Signals Synchronization Technique

In this letter, a new unambiguous tracking technique is proposed for binary offset carrier (BOC) modulated signals, which will be utilized in global navigation satellite systems (GNSS). The proposed technique is a synthesized correlation function obtained by subtracting the cross-correlation between the received BOC signal and the local auxiliary signal from the cross-correlation of BOC signal between another local auxiliary BOC signals. The theoretical standard tracking error formulas are given. The results show that this technique can be a solution to remove the ambiguity completely with slightly degradation in acquisition and tracking for low modulation order BOC signals.

An Omni-directional Wall-climbing Microrobot with Magnetic Wheels Directly Integrated with Electromagnetic Micromotors

This paper presents an omni-directional wall-climbing microrobot with magnetic wheels. The integral design with an actuator and adhesive is realized by integrating stators and rotors of an MEMS-bas...

A Mobile Self-reconfigurable Microrobot with Power and Communication Relays

A modular mobile self-reconfigurable microrobot is developed to enlarge the whole surveillance range of mobile microrobot. The microrobot is designed as differential driven vehicle equipped with a passive universal connector with autonomic engagement/disengagement function, and actuated by MEMS-based electromagnetic micromotors. To realize that the microrobot is autonomous, its electrical system is designed in modularity and integrated. A simple autonomous docking approach based on infrared sensors is presented. Experimental results verify high efficiency and reliability of the proposed docking method, and demonstrate the improved ability of performing large-range vision-based surveillance by power and communication relays.

Wheels Optimization and Vision Control of Omni-directional Mobile Microrobot

This paper presents a millimeters scale omni-directional mobile microrobot with special dual-wheel structure. The microrobot was actuated by three electromagnetic micromotors of 2mm diameter. Dynamic analysis of translational and steering movements presented the relationship between the sizes of the dual-wheel structure and the output torque of the micromotor. Genetic algorithm (GA) was employed to optimize the dual-wheels sizes for reducing the unnecessary torque consumption and improving the driving ability of the microrobot. A computer vision system contained two sets of feedback control is devised for the microrobot. Torque self-balance and current-limiting control approach are presented to ensure the accuracy of step movement. Experiment results demonstrate the feasibility of these concepts.

Energy-efficient and low-delay scheduling scheme for low power wireless sensor network with real-time data flows

In this paper, we propose an energy-efficient and low-delay scheduling EELDS scheme for interruptible preamble sampling-based medium access control MAC protocols e.g., BoX-MAC-2 and X-MAC in IEEE 802.15.4 wireless sensor network WSN, which considers energy efficiency while reducing delay and contention in the context of real-time data gathering and remote monitoring applications. It is built on MAC layer and exploits local information to coordinate the MAC schedules of nodes in a slowly-changing topology, just with light overhead. The scheme also considers the adaptation to data aggregation with real-time data flows. Therefore, our scheme allows for much longer network lifetime while satisfying the delay constraints. The implementation and simulation results show the performance of the proposed scheme.

Design and Optimization of an Omnidirectional Permanent-Magnetic Wheeled Wall-Climbing Microrobot with MEMS-Based Electromagnetic Micromotors

The paper presents a compact omnidirectional permanent-magnetic wheeled wall-climbing microrobot. A millimeter-sized axial flux electromagnetic micromotor based on MEMS technology has been specially fabricated for the microrobot and its size is 6.8 mm × 7.8 mm × 3.9 mm. A novel permanent-magnetic wheel is designed, which is directly integrated with the stators and rotor of the electromagnetic micromotor. The omnidirectional wall-climbing mechanism is realized by a set of steering gears and three standard permanent-magnetic wheels. By static and dynamic force analysis of the microrobot, the required magnetic force and the required torques for its translational and steering movements are derived. To reduce the unnecessary torque consumption of the microrobot, its structural parameters are optimized in combination with its design constraints by ANSOFT and Pro/Engineer simulation. A prototype of the proposed microrobot with the maximum designed load capacity of 3 g is developed, whose size is 26 mm in diameter and 16.4 mm in height. Experimental and simulation results demonstrate the feasibility of these concepts.

A Magnetic Wheel Structure for an Omni-directional Microrobot to Limit Slip Effect

To fulfill the microassembly work successfully, an omnidirectional mobile microrobot is presented. To finish the micron size task, the positioning precision of the robot is highly important. But some unpredictable factors, especially the slip effect in wheel, would affect the precision of the robot and cause unwanted deviation. To limit the deviation and optimize the positioning performance of the robot, a new wheel structure is designed. The design of the new wheel is based on magnetic principle while considering the potential problems brought by the magnetic units. With nonlinear dynamic analysis with slip of the microrobot and simulations based on it, the slippage effect is shown to be limited a lot with the application of new wheel structure. And following experiments are executed to verify the optimization brought by the magnetic wheel structure.

An Omnidirectional Mobile Millimeters Size Micro-Robot with Novel Duel-Wheels

A millimeters size omni-directional mobile micro-robot is presented in this paper. A unique duel-wheel structure is designed for no-slip motion during the steering, by turning the slip friction between the wheel and ground into rolling friction. The robot was driven by four electromagnetic micromotors with 2.1mm×2.1mm×1.3mm size. Three of them are for translation and the other one is for rotation. Kinematics model is analyzed to prove the omni-directional mobility. Virtual-Winding Approach (VWA) and PWM-Based Vector-Synthesize Approach(PBVSA) current control methods are presented to satisfy a requirement of higher positioning accuracy. Experimental results demonstrate the feasibility of this concept.

Infrared communication link maintaining method for multiple mobile microrobots

The paper presents a method of infrared communication link maintaining for multiple mobile microrobots, so as to enlarge their whole inspection range. A carrier sense multiple access protocol of infrared communication is employed. A motion control model based on virtual spring-damper system is established to avoid communication network splitting by monitoring infrared link quantity information among nodes. To verify the method above, a case study on infrared communication maintenance between the task-executed mobile microrobot and the base station is presented, in which the task-executed mobile microrobot executes a task and a team of microrobots act as communication relay nodes. The relative experiments are performed, and the feasibility of the method is verified.