Baofeng Gao

Motion-control analysis of ICPF-actuated underwater biomimetic microrobots

This paper introduces the development of biomimetic underwater microrobots consisting of AVR microcontroller, an infrared ray communication system, and ionic conducting polymer film (ICPF) actuators. We use AVR ATmega16 as the control unit and an infrared ray receiver to provide feedback to the AVR unit. The spiral particle pathway searching approach is developed to search for particles. We also use MATLAB and OpenGL to simulate the path planning and optimisation according to the particle swarm optimisation algorithm. We implemented and demonstrated wireless control over the trajectory of individual microrobot, and extended this to three units in an expect formation.

A Novel Soft Biomimetic Microrobot with Two Motion Attitudes

A variety of microrobots have commonly been used in the fields of biomedical engineering and underwater operations during the last few years. Thanks to their compact structure, low driving power, and simple control systems, microrobots can complete a variety of underwater tasks, even in limited spaces. To accomplish our objectives, we previously designed several bio-inspired underwater microrobots with compact structure, flexibility, and multi-functionality, using ionic polymer metal composite (IPMC) actuators. To implement high-position precision for IPMC legs, in the present research, we proposed an electromechanical model of an IPMC actuator and analysed the deformation and actuating force of an equivalent IPMC cantilever beam, which could be used to design biomimetic legs, fingers, or fins for an underwater microrobot. We then evaluated the tip displacement of an IPMC actuator experimentally. The experimental deflections fit the theoretical values very well when the driving frequency was larger than 1 Hz. To realise the necessary multi-functionality for adapting to complex underwater environments, we introduced a walking biomimetic microrobot with two kinds of motion attitudes: a lying state and a standing state. The microrobot uses eleven IPMC actuators to move and two shape memory alloy (SMA) actuators to change its motion attitude. In the lying state, the microrobot implements stick-insect-inspired walking/rotating motion, fish-like swimming motion, horizontal grasping motion, and floating motion. In the standing state, it implements inchworm-inspired crawling motion in two horizontal directions and grasping motion in the vertical direction. We constructed a prototype of this biomimetic microrobot and evaluated its walking, rotating, and floating speeds experimentally. The experimental results indicated that the robot could attain a maximum walking speed of 3.6 mm/s, a maximum rotational speed of 9°/s, and a maximum floating speed of 7.14 mm/s. Obstacle-avoidance and swimming experiments were also carried out to demonstrate its multi-functionality.

Comparison of sEMG-Based Feature Extraction and Motion Classification Methods for Upper-Limb Movement

The surface electromyography (sEMG) technique is proposed for muscle activation detection and intuitive control of prostheses or robot arms. Motion recognition is widely used to map sEMG signals to the target motions. One of the main factors preventing the implementation of this kind of method for real-time applications is the unsatisfactory motion recognition rate and time consumption. The purpose of this paper is to compare eight combinations of four feature extraction methods (Root Mean Square (RMS), Detrended Fluctuation Analysis (DFA), Weight Peaks (WP), and Muscular Model (MM)) and two classifiers (Neural Networks (NN) and Support Vector Machine (SVM)), for the task of mapping sEMG signals to eight upper-limb motions, to find out the relation between these methods and propose a proper combination to solve this issue. Seven subjects participated in the experiment and six muscles of the upper-limb were selected to record sEMG signals. The experimental results showed that NN classifier obtained the highest recognition accuracy rate (88.7%) during the training process while SVM performed better in real-time experiments (85.9%). For time consumption, SVM took less time than NN during the training process but needed more time for real-time computation. Among the four feature extraction methods, WP had the highest recognition rate for the training process (97.7%) while MM performed the best during real-time tests (94.3%). The combination of MM and NN is recommended for strict real-time applications while a combination of MM and SVM will be more suitable when time consumption is not a key requirement.

Design of a Novel Telerehabilitation System with a Force-Sensing Mechanism

Many stroke patients are expected to rehabilitate at home, which limits their access to proper rehabilitation equipment, treatment, or assessment by therapists. We have developed a novel telerehabilitation system that incorporates a human-upper-limb-like device and an exoskeleton device. The system is designed to provide the feeling of real therapist–patient contact via telerehabilitation. We applied the principle of a series elastic actuator to both the master and slave devices. On the master side, the therapist can operate the device in a rehabilitation center. When performing passive training, the master device can detect the therapist’s motion while controlling the deflection of elastic elements to near-zero, and the patient can receive the motion via the exoskeleton device. When performing active training, the design of the force-sensing mechanism in the master device can detect the assisting force added by the therapist. The force-sensing mechanism also allows force detection with an angle sensor. Patients’ safety is guaranteed by monitoring the motor’s current from the exoskeleton device. To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients’ safety. Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication.

Development of an Infrared Ray controlled fish-like underwater microrobot

Novel materials such as ICPF has been used as actuators in underwater microrobot for many years, and this paper developed an individual fish-like underwater microrobot which consists of ATMEL AVR minimum control system, Infrared Ray Data Association system and ICPF (Ionic Conducting Polymer Film) actuators. We use atmega16 as the control centre of the mechanical and control system of the microrobot, Infrared Ray receiver receive the infrared signal and give feed back voltage signal to AVR, then AVR sent square control signal to the electric relay as the circuit changer to adjust the input voltage signal of ICPF actuator and make the microrobot carrying out different motion underwater. The infrared communication system could be used for communication between the microrobot and mother submarine with 940nm 38k infrared ray. We discussed the infrared ray control signals on the ICPF actuator, and gave the basic communication code of microrobot. At last, we set up experiment to test the possibility of control signals on ICPF actuator and use Infrared ray control the single microrobot, the result show us the possibility of microrobot pre-movement and direction change movement driven by different type control signals. At last, we set up the experiment to make three microrobot keep the formation and go ahead together.

Implementation of Human-Machine Synchronization Control for Active Rehabilitation Using an Inertia Sensor

According to neuro-rehabilitation practice, active training is effective for mild stroke patients, which means these patients are able to recovery effective when they perform the training to overcome certain resistance by themselves. Therefore, for rehabilitation devices without backdrivability, implementation of human-machine synchronization is important and a precondition to perform active training. In this paper, a method to implement this precondition is proposed and applied in a user’s performance of elbow flexions and extensions when he wore an upper limb exoskeleton rehabilitation device (ULERD), which is portable, wearable and non-backdrivable. In this method, an inertia sensor is adapted to detect the motion of the user’s forearm. In order to get a smooth value of the velocity of the user’s forearm, an adaptive weighted average filtering is applied. On the other hand, to obtain accurate tracking performance, a double close-loop control is proposed to realize real-time and stable tracking. Experiments have been conducted to prove that these methods are effective and feasible for active rehabilitation.

Dynamic mechanics and electric field analysis of an ICPF actuated fish-like underwater microrobot

As the development of the ICPF (ionic conducting polymer films) actuator in MEMS, it has been one of the most interested materials due to its large bending deflection, high mechanical deformation, low excitation voltage, low density and manufacturing cost. In this paper, we will present the Cube Minimum Unit Model according to the hypothesis of considerable mechanical deformation principle of the ICPF actuator, and discuss the material relationships for ICPF actuator being recognized as a isotropic material, and show the equations of the forces, bending moment and transverse shear forces. We also give the electric field and stress analysis of the ICPF actuator based on the equivalent electrical circuit model and resolve the subject of output stress control based on the open-loop response. For the fish-like underwater microrobot, the ICPF actuated fish fin is an important mechanism, we will use ANSYS to give the dynamics analysis and improve the moving performance of the fish-like underwater microrobot by revising the shape of fish fin.

Development of an Infrared Sensor-based Wireless Intelligent Fish-like Underwater Microrobot

This paper is about an Infrared Sensor-based Wireless Intelligent Fish-like Underwater Microrobot. We will study on the AVR (Armoured Vehicle Reconnaissance) minimum control system, IRDA (The Infrared Ray Data Association) infrared communication system and ICPF (Ionic Conducting Polymer Film) actuators for underwater microrobot motion control. The AVR control system use atmega16 as the centre of the mechanical and control system of the microrobot, sent square control signal to the ICPF actuator, and use the electric relay G6S-2 as the circuit changer to change the input voltage of ICPF actuator to make the microrobot carrying out different motions underwater. The IRDA infrared communication system can be used for communication between the microrobot and mother submarine with 940nm 38k infrared ray. At last, the experiment results show us it is possible for the microrobot to realize motion movement underwater.

A Novel Underwater Crablike Microrobot

In this paper, we presents a novel crablike underwater microrobot named crabliker-1. The designed microrobot has eight legs, and each leg is made up of two pieces of ICPF (ionic conducting polymer film). A new analysis method to the gait of the microrobot is proposed. Based on this method, three processes of single legs movement under different control signals are proposed. The structure and motion mechanism are given. The kinematics of single leg is discussed. And then, we set up the experimental platform to analyze the characteristics of the ICPF actuator. At last, the rightwards movement and circumvolve anticlockwise of the microrobots gait are carried out

A method of decreasing time delay for a tele-surgery system

The haptics-based master-slave system for Minimally Invasive Surgery is a promising way to protect surgeons from long time radiation and to train novice doctors to learn basic wire or catheter handling skills. However, the time delay of transmission of visual video and the time difference between image information and force signals restrict the application of this technology in some extent. In this paper, we proposed a new method to reduce time delay effectively. At the slave side, the tip of the active catheter is tracked in real time to provide information on the location of the catheter in the blood vessel model. And then transmitted the coordinate values to the master site. At the master site, the location of the catheter was reappeared in the navigation chart which is the same structure with the blood vessels at master side according to the coordinate values received from the slave side. Therefore the transmission time of image information is decreased. Experimental results are given to illustrate the accuracy of our method.