Liang Jianhong

Hybrid undulatory kinematics of a robotic Mackerel ( Scomber scombrus ): Theoretical modeling and experimental investigation

Fishes that use undulatory locomotion occasionally change their inherent kinematics in terms of some natural behavior. This special locomotion pattern was vividly dubbed “hybrid kinematics” by biologists recently. In this paper, we employed a physical model with body shape of a Mackerel (Scomber scombrus), to use the three most typical undulatory kinematics: anguillform, carangiform and thunniform, to investigate the hydrodynamic performance of the so-called “hybrid kinematics” biological issue. Theoretical models of both kinematics and hydrodynamics of the physical model swimming were developed. Base on this model, the instantaneous force produced by fish undulatory body and flapping tail were calculated separately. We also quantitatively measured the hydrodynamic variables of the robotic model swimming with the three undulatory kinematics on an experimental apparatus. The results of both theoretical model and experiment showed that the robot with thunniform kinematics not only reaches a higher speed but also is more efficient during steady swimming mode. However, anguilliform kinematics won the speed race during the initial acceleration. Additionally, the digital particle image velocimetry (DPIV) results showed some difference of the wake flow generated by the robotic swimmer among the three undulatory kinematics. Our findings may possibly shed light on the motion control of a biomimetic robotic fish and provide certain evidence of why the “hybrid kinematics” exists within the typical undulatory locomotion patterns.

Attitude estimation for small helicopter using extended kalman filter

Accurate attitude estimation is vital for VTOL UAV (vertical take-off and landing unmanned aerial vehicle) systems, including small helicopter. The main focus of present research is to compile the principles of navigation and Kalman filtering, and their application and implementation towards UAV systems. This paper introduces a method based on EKF (Extended Kalman filter) to estimate small helicopter¿s attitude with little drift and low noise, which uses strapdown attitude as state update, and treats the attitude estimated by the bi-vector method as measurement update. By evaluating the EKF method with small helicopters real ground and flight sensor data, it shows good performance: stable, small error. So it is suitable for small helicopter attitude estimation application.

On the thrust performance of an ionic polymer-metal composite actuated robotic fish: Modeling and experimental investigation

In this paper, we theoretically predict and experimentally measure the thrust efficiency of a biomimetic robotic fish, which is propelled by an ionic polymer-metal composite (IPMC) actuator. A physics-based model that consists of IPMC dynamics and hydrodynamics was proposed, and simulation was conducted. In order to test the thrust performance of the robotic fish, a novel experimental apparatus was developed for hydrodynamic experiments. Under a servo towing system, the IPMC fish swam at a self-propelled speed where external force is averagely zero. Experimental results demonstrated that the theoretical model can well predict the thrust efficiency of the robotic fish. A maximum thrust efficiency of 2.3×10−3 at 1 Hz was recorded experimentally, the maximum thrust force was 0.0253 N, recorded at 1.2 Hz, while the maximum speed was 0.021 m/s, recorded at 1.5 Hz, and a peak power of 0.36 W was recorded at 2.6 Hz. Additionally, the optimal actuation frequency for the thrust efficiency was also recorded at the maximum self-propelled speed. The present method of examining the thrust efficiency may also be applied to the studies of other types of smart material actuated underwater robots.

An Attitude Estimate Approach using MEMS Sensors for Small UAVs

For the small UAVs (unmanned aerial vehicle) using MEMS sensors, this article puts forward a Kahnan Filter model to get attitude estimate without long term drift and showing relatively smaller error. Firstly, strapdown inertial attitude algorithm and bi-vector attitude algorithm are presented, which are widely used in small UAV autopilot systems now. However, there is a problem of long term drift with the former and heavy noise with the latter. Due to these shortcomings, accurate attitude control has not been achieved yet in small UAVs. In order to solve these problems, this paper gives out a Kalman filter model which fuses the two types of data into an optimal estimate of real attitude, and overcomes the shortages of both algorithms mentioned above. Simulation results show that this filter can be used to gain fairly good data for more accurate attitude control. Besides, compared with the filters already developed, this Kalman filter has a relatively low order and a loose architecture, which could be more easily adopted in an existed embedded computer system of small UAV.

Reconfiguration Research on Modular Mobile Robot

The reconfigurable tracked mobile robot was developed for all-terrain recon. Based on the unique characters of reconfigurable robot, modular mechanical and electrical structure and control method were all discussed. The tracked robot was composed of four basic locomotion modules, three joint rods and two rotational articulations. By the different configurations of all the modules, the mechanical reconfiguration of the tracked vehicle was realized. The master-slave control system was adopted. Based on the ARM real time embedded control system, the reconfiguration was realized when the mechanical structure of the robot was reconfigured. The tracked robot was validated that it has the excellent adaptable ability in complex terrain and has easy and simple reconfigurable performance when it executed recon in the building interior simulating the real task

Modularization of Miniature Tracked Reconnaissance Robot

This paper analyzes the demanding background of the tracked reconnaissance robot, and its requisite performance is discussed in detail. According to the demand, the miniature tracked reconnaissance robot (MTRR) is developed in Beihang University. The purpose of this paper is to discuss the application of the MTRR system and its modularization design methods. The meanings of modularization are that: structure modularization, control system modularization and software modularization. The MTRR system of small size and light weight is characterized with reconfiguration and portable performance. Furthermore, the system is provided with waterproof and shock-resistant performance

An adaptive system identification method for a micro unmanned helicopter robot

Focusing on the dynamic model parameter identification problem, this paper proposed an adaptive linear-time-domain system identification method for the micro unmanned helicopter robot. Based on the flash memory in the Micro Guide Navigation Control (MGNC), system recorded the flight data sequences regarding the input signal for servos and output signals for attitude and velocity information. Through the adaptive genetic algorithm, the system can construct the high precise dynamic state space model for the micro unmanned helicopter robot. Finally, the effectiveness of the identified model is verified by a series of simulation and tests. The micro unmanned helicopter robot can finish hover, turn, and straight flight tasks.

The design and application of a sUAV system for antarctic expedition

Antarctic conditions are critical, which means low attitude flight is quite dangerous. However, with the development of the polar expedition and the upgrade of miniature sensor equipments, the introduction of small unmanned aircraft systems as a new polar expedition method, is one of the international forefront innovative research. This paper will introduce the background, research, development and scientific research flight of a small unmanned aircraft system (sUAV), which is aimed to the scientific expedition use in Antarctica.

Experimental design and performance of underwater vehicle based on capacity of voyage

The SPC-3 UUV robofish prototype is an experimental vehicle especially designed to improve efficiency of thrust and capacity of voyage based on the SPC-2 UUV robofish by Beijing University of Aeronautics and Astronautics. According to the record of power acquisition computer and camera which is used to measure the power and velocity of SPC-3 UUV in the still water, the speed-frequency and power-frequency curve were bulit. According to the estimation of capacity of voyage, the voyage time and voyage on condition of different frequency of flapping foils were calculated, the propulsion frequency could be selected base on the cruising velocity as well as voyage capacity. Experimental result of the long voyage performance in Bei Daihe showed that SPC-3 UUV achieved 22.761 kilometers, and its voyage time was 6.25 h, and obtain a average cruising speed as 1.03 m/s using the optimal frequency ranging from 1.5~1.6Hz of the flapping foils.

An approach to ground target localization for UAVs based on multi-sensor fusion

In this paper, an approach based on multiple airborne sensors fusion to ground target localization for UAVs is proposed, which is the basis of UAVs applications, such as obstacle avoidance, target confirmation, etc. Challenges from accuracy improvement and system disturbance are considered. Sensor information is obtained by a visual sensor, GPS, and IMU modules. Traditional methods are mainly aimed at an upright position for visual sensors. First of all, an online multi-sensor calibration method using GPS is designed, calibrating the orientation of the visual sensor to the UAVs location. Then the target can be detected using Adaboost algorithm based on acquisition information of different visual sensors. And information obtained by real-time GPS, IMU, altimeter, and visual image based on Kalman filter is fused for target localization. Finally a D-S method for estimating the confidence level of target location is designed for perception disturbance. Experiments are implemented on rotor aircrafts and fixed-wing UAVs and the results show that the method, as feasible as it is, can effectively percept disturbance and improve location accuracy of a certain target.