Wei Hongxing

Control of a self-assembly modular robot system over a wireless ZigBee network

This paper emphasizes the control problem of a self-assembly modular robot with wireless network load. A self-assembly modular robot driven by four micro DC motors is used as an example, which is named Sambot. Each motor is controlled by a separate microcontroller-ATMega8 for driving, and the ATMega8 also complete the encoder and sensor information collection, the left and right wheel drive motor are used for the control of linear and angular velocities of the robot modular, the other one motor is used for the docking-platform rotating between two robot modular, and the last one motor is used for the hook lock after successfully docking. A Zigbee network is implemented between each other modular robot uses TIs CC2430 chip with C51 microcontroller core for the realization of the underlying layer protocol stack and upper layer application, and a CAN Bus communication uses VP230 as CAN transceiver to connect with the CAN interface when they are docking locked. The wireless network controlled system and the communication network are simulated respectively with Matlab/Simulink and Truetime, and the mobile self-assembly robot control and communication system has been a very good real-time and lowjitter validation.

A Middleware Based Control Architecture for Modular Robot Systems

Robot technology has been widely used in industrial production and daily life. Unfortunately, due to the uncertainty of the environment and the diversity of functions, the complexity of the robot software is growing dramatically, in which a lot of repetitive works are done. To solve this problem, the modularization of robots and robot middleware has been proposed. From the perspective of modularization, interoperability, scalability and ease-of-use, this paper proposes a loose-coupled, service-oriented modular robot middleware (MoRoM) architecture. In this architecture, we define the standard interface to encapsulate services each functional component provides, realize system automatic configuration (plug and play), and provide a message notification mechanism as well as program frameworks. To verify the proposed middleware, we implement it using ACE-TAO, which is a real-time CORBA implementation, and test it in a modular robot system. The test shows that this architecture is suitable for improving reusability, interoperability and scalability of robot software.

Curriculum of Embedded System for Software Colleges

Embedded system has already been applied in numerous fields, such as the industry control system, information appliances, communication equipments, medical instruments, intelligence instruments and so on. As processors become more powerful, electronic products become more complex. Embedded system designers are able to include design features traditionally associated with personal computer (PC) including graphical user interfaces, TCP/IP networking, and database management. For introducing knowledge of embedded system to student of Master of Software Engineering (MSE), the Software College at Tsinghua University and Beihang University had an opportunity to add technical electives for embedded system, the author received approval to teach embedded system design course. This paper describes the development and implementation of that course toward the goal of teaching students the hardware considerations, software considerations, and design processes involved in embedded system design. In the end, the teaching effect of course for embedded system design is analyzed

A smart metering system for monitoring electricity of building based on wireless network

This paper presents a monitoring system of building electricity using IPv6 to establish a network. This smart metering system consists of three parts: the host software, the network and the sensor nodes. The network, whose data transmits via Zigbee wireless communication protocol, is designed based-on IPv6 protocol, and builds the IPv6 protocol on IEEE 802.15.4 wireless network. The Sensor node has a unique IP address and the sampling rate is set according to the host system. With real-time measurement of power, current and voltage values including RMS, instantaneous value and peak value, each node achieved accurate data sampling and communication stability. The host software is designed for building test characteristics, having a tree hierarchy and friendly interface to user. The reliability and accuracy of this monitoring system are verified in the experiment.

Trajectory planning based on latitude for painting on spherical surface

A latitude method for the trajectory planning of spraying on spherical surface is presented. The latitude method is used to optimize the time and coating thickness in the spray painting. The start curve, the velocity of the spray gun and the width between neighboring paths are the main factors to affect the final coating quality. Spray painting time is determined by the start curve of the gun, while selection of the velocity and width contribute to the coating thickness together. Based on the paint deposition model of flat surface, the deposition model on the cylindrical surface is derived. The start curve on the spherical surface is derived from the Bounding-Box method. The spray gun velocity and the width between neighboring paths are determined through the optical function in which the coating thickness is the optimized target. The simulation shows that the latitude method presented in this paper can solve the problem of the trajectory planning on spherical surface.

A digital high performance PMSM servo system based on DSP and FPGA

This paper concerns a kind of high performance permanent magnet synchronous servo system. Based on analyzing the mathematical model and vector control theory of permanent magnet synchronous motor, a method is applied to design servo system, which makes the current of D axis equal to zero. The system uses FPGA and DSP as the control unit, which increase the computation ability, simplify the circuit and guarantee the system stability. After analyzing the key links of the permanent magnet synchronous servo system, we discuss how to realize multi-loop control system through programming. Finally, the experimental course and the testing results on the numerical control machine of the designed system are given, which are the evidences of system correctness and system feasibility.

Comparison between model reference observer and reduced order observer of PMSM torque

The load torque disturbance influences the performance of permanent magnet synchronous motor speed control. Therefore, to compensate this problem, this paper designed a model reference torque observer based on Popov-super-stability theory. This observer uses off-line calculation to obtain the model parameters and PI calculation of the speed model error to get the load torque. This structure is simple and easy to implement for speed control compensation. The compare of this observer and a reduced order torque observer is studied by simulation. The results show that the model reference observer designed this paper has better performance in convergence, noise immunity and observation accuracy, and is more suitable for speed control compensation.

Adaptive model following speed control method of permanent magnet synchronous motor

Permanent magnet synchronous motor (PMSM) servo system requires a high dynamic performance of speed. The control object of speed loop, which can be described using a two-order transfer function, is the PMSM regulated by current loop. PI controller is generally used in speed control, in which the performance improvement is limited by the strong coupling and nonlinearity of the system. In this paper, an adaptive model following speed controller (AMFC) with state feedback control and model following methods is designed based on the Popov hyperstability theory and modeled in the MATLAB. The simulation results show that, compared with PI control, AMFC raises the speed loop dynamic performance of PMSM by compensating the influence of coupling and nonlinearity, so it is more suitable for servo system.

A new dual-core Permanent Magnet Synchronous Motor Servo System

A new Permanent Magnet Synchronous Motor (PMSM) Servo System is designed based on the dual-core composed of digital signal processor (DSP) and field programmable gate array (FPGA). The dual-core combined of DSP and FPGA achieves the control algorithm by assigning the tasks. The design of external circuit using FPGA simplifies the system structure and enhances the stability. DSP program with multi-interrupt drives the IPM module through pulse-width modulation (PWM) signals. The improved control methods of the three loops of PMSM servo system are achieved in interrupt program: the self-tuning control based on resistance and inductance observer is used in current loop, which ameliorate the following accuracy of current. In order to reduce the response overshoot, the speed is controlled by the integral-separated and limit-weaken PID controller. The feed-forward is added to the proportional position control to reduce the dynamic response error. The application on CNC lathe verifies the feasibility of the design of dual-core system and the control methods of the three loops.

Impedance control of robot manipulator with model reference torque observer

The impedance control is an effective way to adjust both the position and the force of the manipulator of the robot so as to accommodate the request of the application in some fields such as industry and aerospace. The algorithm is implemented into two control loops. The inner loop is the position control to ensure the precision operation of the manipulator, which uses the forward and inverse kinematics solution and rely on the closed-loop control of the joint driver. The outer loop is the impedance control which achieves the implementation of the force control between the manipulator and the environment by adjusting the impedance model. This loop outputs a correction to the position loop that includes the force control information. One problem of impedance control is that the force sensors used to measure the react force of the environment increase the complexity and reduce the reliability of the system. A model reference torque observer of the joint, which using permanent magnet synchronous motor (PMSM) as the actuator, is presented and applied to the impedance control loop. The simulation results show the correctness and feasibility of this algorithm.