Evolving controllers for autonomous robot search teams

Deploying autonomous robot teams instead of humans in hazardous search and rescue missions could provide immeasurable benefits. In such operations, rescue workers often face environments where information about the physical conditions is impossible to obtain, which not only hampers the efficiency and effectiveness of the effort, but also places the rescuers in life-threatening situations. These types of risk promote the potential for using robot search teams in place of humans. This article presents the design and implementation of controllers to provide robots with appropriate behavior. The effective utilization of genetic algorithms to evolve controllers for teams of homogeneous autonomous robots for area coverage in search and rescue missions is described, along with a presentation of a robotic simulation program which was designed and developed. The main objective of this study was to contribute to efforts which attempt to implement real-world robotic solutions for search and rescue missions.     

Bionic autonomous learning control of a two-wheeled self-balancing flexible robot

This paper presents an OCPA (operant conditioning probabilistic automaton) bionic autonomous learning system based on Skinner’s operant conditioning theory for solving the balance control problem of a two-wheeled flexible robot. The OCPA learning system consists of two stages: in the first stage, an operant action is selected stochastically from a set of operant actions and then used as the input of the control system; in the second stage, the learning system gathers the orientation information of the system and uses it for optimization until achieves control target. At the same time, the size of the operant action set can be automatically reduced during the learning process for avoiding little probability event. Theory analysis is made for the designed OCPA learning system in the paper, which theoretically proves the convergence of operant conditioning learning mechanism in OCPA learning system, namely the operant action entropy will converge to minimum with the learning process. And then OCPA learning system is applied to posture balanced control of two-wheeled flexible self-balanced robots. Robot does not have posutre balanced skill in initial state and the selecting probability of each operant in operant sets is equal. With the learning proceeding, the selected probabilities of optimal operant gradually tend to one and the operant action entropy gradually tends to minimum, and so robot gradually learned the posture balanced skill.     

Biomimetic flexible/compliant sensors for a soft-body lamprey-like robot

This paper focuses on the development of biomimetic sensory abilities for an undulatory soft-body lamprey-like robot, which has been designed to replicate the locomotion mechanisms of living lamprey in order to address useful applications wherever locomotion in unstructured environments is required. The compliant sensory elements are piezo-resistive and made from compliant material called a quantum tunneling composite by mixing micro/nano carbon black particles into a highly soft silicone rubber matrix. The relationship of the composite strip between piezo-resistivity and mechanical strain is investigated by a universal strain–stress tensiometer through resistivity monitoring. Increasing and decreasing resitivity both appears during elongation and retraction, suggesting that piezo-resistivity in the composite material is governed by both percolation theory and quantum tunneling effects. Dynamic tests on the bench shows that the compliant stretch receptor is able to follow the stimulations under fairly wide frequency ranges, exceeding initial estimations. In addition, the compliant artificial stretch receptor has enough sensitivity to detect the local actuations and the actions generated by neighboring actuators in the segmented robotic structure. Finally, the experiments on biomimetic cilia-based cupula receptor show that a low cost flexible/compliant biomimetic sensor is able to detect medium fluidic speeds ranging from 0.05 m/s to 0.6 m/s.     

自主柔性变形蛇形机器人控制系统设计

针对搜救机器人对多信息获取与处理、远程监控与运动控制的实时高性能需求,设计了以ARM微处理器STM32为核心、多传感器融合的自主柔性变形蛇形机器人控制系统,实现了机器人的远程监控与运动控制、多传感器环境信息采集等功能。整个控制系统具有良好的扩展性、硬件可裁剪性。通过模拟灾难废墟场景实验,结果表明：蛇形机器人控制系统可实现多信息的实时准确无线通信,在不同的环境中,具有良好的多步态运动稳定性和自主移动性能。     

Active force-torque robot control without using wrist force-torque sensors

A method of active force-torque control of manipulator robots is considered; in this method it is proposed to use signals proportional to elastic deformations of flexible elements of the manipulators as feedback signals, rather than conventional forces and moments of reactions arising under the contact of the gripper and the moved object. It is proposed to construct control laws which are the functions of these feedback constraints in such a way that they generate artificial potential control forces. Due to it, unlike conventional approaches, simple and natural stability conditions are provided, as well as the weak dependence of dynamic properties of the control system on the variation of its parameters, i.e., the parametric robustness of the system.     

Design of robot controllers

The decoupling method is applied to the design of position-speed-acceleration and force/position-speed-acceleration robot controllers. For this purpose, the Cartesian approach and the decoupling method are used to derive the generating rules of the control laws to be implemented in these systems. In this paper, only the case of non-redundant robots is considered.     

Optimization of interval type-2 fuzzy logic controllers for a perturbed autonomous wheeled mobile robot using genetic algorithms

We describe a tracking controller for the dynamic model of a unicycle mobile robot by integrating a kinematic and a torque controller based on type-2 fuzzy logic theory and genetic algorithms. Computer simulations are presented confirming the performance of the tracking controller and its application to different navigation problems.     

Development of a novel autonomous lower extremity exoskeleton robot for walking assistance

Today, exoskeletons are widely applied to provide walking assistance for patients with lower limb motor incapacity. Most existing exoskeletons are under-actuated, resulting in a series of problems, e.g., interference and unnatural gait during walking. In this study, we propose a novel intelligent autonomous lower extremity exoskeleton (Auto-LEE), aiming at improving the user experience of wearable walking aids and extending their application range. Unlike traditional exoskeletons, Auto-LEE has 10 degrees of freedom, and all the joints are actuated independently by direct current motors, which allows the robot to maintain balance in aiding walking without extra support. The new exoskeleton is designed and developed with a modular structure concept and multi-modal human-robot interfaces are considered in the control system. To validate the ability of self-balancing bipedal walking, three general algorithms for generating walking patterns are researched, and a preliminary experiment is implemented.

     

Development of an indoor navigation system for a monocular-vision-based autonomous mobile robot

We have developed a technology for a robot that uses an indoor navigation system based on visual methods to provide the required autonomy. For robots to run autonomously, it is extremely important that they are able to recognize the surrounding environment and their current location. Because it was not necessary to use plural external world sensors, we built a navigation system in our test environment that reduced the burden of information processing mainly by using sight information from a monocular camera. In addition, we used only natural landmarks such as walls, because we assumed that the environment was a human one. In this article we discuss and explain two modules: a self-position recognition system and an obstacle recognition system. In both systems, the recognition is based on image processing of the sight information provided by the robot’s camera. In addition, in order to provide autonomy for the robot, we use an encoder and information from a two-dimensional space map given beforehand. Here, we explain the navigation system that integrates these two modules. We applied this system to a robot in an indoor environment and evaluated its performance, and in a discussion of our experimental results we consider the resulting problems.     

Development of tethered autonomous mobile robot systems for field works

This paper describes the implementation details, advantages and potential applications of autonomous tethered mobile robot systems using the 'hyper-tether' concept. Hyper-tether is a new research area on tethered connections, which provide tethering among different mobile robot types, such as a robot with the environment and a robot with humans and animals. Its basic function is to actively control the tether's tension and/or length, but it also considers tether launching, anchoring, power delivery, data communication cabling and built-in trajectory command generation capabilities. Many of these features can be efficiently applied to build a tethered mobile robot system which remotely manipulates a working tool that can be useful for land-mine detection and removal, trimming of gardens and grass cutting of wide areas (e.g. golf courses, soccer and baseball fields), spraying of agricultural chemicals, forestry and construction works, etc. In this paper, a simple prototype of hypertether's winch-tether pair and a working tool equipped with a grass cutter was constructed, and basic experiments were performed to demonstrate the validity of the proposed system.     

Robo-Erectus: a low-cost autonomous humanoid soccer robot

An exoskeleton robot can replace the wearer's motion function by operating the human's body. The purpose of this study is to propose a power assist method of walking, standing up and going up stairs based on autonomous motion of the exoskeleton robot suit, HAL (Hybrid assistive Limb), and verify the effectiveness of this method by experiment. In order to realize power assist of tasks (walking, standing up and going up stairs) autonomically, we used the Phase Sequence control which generates a task by transiting some simple basic motions called Phases. A task was divided into some Phases on the basis of the task performed by a normal person. The joint moving modes were categorized into active, passive and free modes according to the characteristic of the muscle force conditions. The autonomous motions which HAL generates in each Phase were designed corresponding to one of the categorized modes. The power assist experiments were performed by using the autonomous motion with a focus on the active mode. The experimental results showed that the wearer's muscle activation levels in each Phase were significantly reduced. With this, we confirmed the effectiveness of the proposed assist method.     

Tracking control of a flexible robot link

The formulation of an appropriate hybrid lumped/distributed model of a flexible robot link makes it possible to formulate and study tracking problems without the necessity for a priori approximations in the flexibility model for the link. The use of secondary support beam and active tip control provides perfect tracking with hypothetical exact measurements, and tracking to arbitrary accuracy with use of a variant of the acceleration feedback technique     

Prowling autonomous mobile robot with a network camera

This research aimed to develop an autonomous mobile robot that helps various kinds of people. The evasion of obstacles is absolutely imperative so that the robot can act in a human-life environment. Therefore, we developed a robot that moves through doors and avoids obstacles with the help of images taken by a camera set on the robot. This work was presented in part at the 13th International Symposium on Artifical Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Simulation of a SCARA robot with PD and learning controllers

In this study, a SCARA robot manipulator is simulated under PD and learning based controllers. The trajectory following performance of the robot is studied against these controllers. The adaptive/learning hybrid controller scheme and learning controller method are utilized as learning based controllers. The results of simulations show that, learning algorithm based controllers reduce the position tracking error effectively. The hybrid adaptive/learning controller has similar performance as the learning controller although it uses partial state information and compensates both mechanical and electrical dynamics, whereas the learning controller needs both position and velocity measurements neglecting electrical dynamics.     

Principles and design of model-based robot controllers

Model-based control algorithms for industrial manipulators require the on-line evaluation of robot dynamics and are particularly sensitive to modelling errors. The development of a unifying framework for the analysis and design of model-based robot control strategies is the theme of this paper. In this framework, the practical problems associated with real-time implementation are highlighted and methods to improve the robustness of the closed-loop system are suggested.     

Development of soft and distributed tactile sensors and the application to a humanoid robot

This paper describes a comprehensive tactile sensor system which can cover wide areas of full-body robots. Based on design criteria which are introduced from requirements, we develop two types of tactile sensor elements. One is a multi-valued touch sensor which has multi-level pressure thresholds. It is capable of covering wide areas of robot surfaces. The other is made of soft, conductive gel, which has the advantage of compliance compared with other sheet-type tactile sensors. With these two types sensors, we develop the tactile sensor system on the full-body robot 'H4'. Details of the sensor system on the robot and some experiments using tactile information are described.     

机器人触须传感器的设计

提出了一种利用触须来识别物体表面轮廓的新方法。传感器采用了二维PSD作为敏感元件,实时地测量由于与物体接触在触须根部所产生的微小位移量。介绍了机器人触须传感器具体的结构及工作原理。由实验数据可知,触须根部位移量的大小与接触的距离成反比,且距离越近位移量变化的速度越快。由此可获得待测物体的位置、距离、角度等信息。     

Hitting robot with a flexible link hammer

This paper describes a hammering robot with a flexible link which can hit an object from an arbitrary direction in 3-dimensional space. A dynamic equation for the flexible link hammer is presented by taking gravity into consideration. The necessary conditions for the hammer to strike an object square-on with the only velocity normal to its face are investigated, and a manipulating method to satisfy these hitting conditions is obtained. Some applicatons of the hitting robot are given. This work was presented, in part, at the Third International Symposium on Artificial Life and Robotics, Oita, Japan January 19–21, 1998.     

Design of an autonomous agricultural robot

This paper presents a state-of-the-art review in the development of autonomous agricultural robots including guidance systems, greenhouse autonomous systems and fruit-harvesting robots. A general concept for a field crops robotic machine to selectively harvest easily bruised fruit and vegetables is designed. Future trends that must be pursued in order to make robots a viable option for agricultural operations are focused upon.A prototype machine which includes part of this design has been implemented for melon harvesting. The machine consists of a Cartesian manipulator mounted on a mobile chassis pulled by a tractor. Two vision sensors are used to locate the fruit and guide the robotic arm toward it. A gripper grasps the melon and detaches it from the vine. The real-time control hardware architecture consists of a blackboard system, with autonomous modules for sensing, planning and control connected through a PC bus. Approximately 85% of the fruit are successfully located and harvested.     

Fabrication of micro sensors on a flexible substrate

Flexible micro temperature and humidity sensors on parylene thin films were designed and fabricated using a micro-electro-mechanical-systems (MEMS) process. Based on the principles of the thermistor and the ability of a polymer to absorb moisture, the sensing device comprised gold wire and polyimide film. The flexible micro sensors were patterned between two pieces of parylene thin film that had been etched using O₂ plasma to open the contact pads. The sacrificial Cr spacer layer was removed from the Cr etchant to release the flexible temperature and humidity sensors from the silicon substrate. Au was used to form the sensing electrode of the sensors while Ti formed the adhesion layer between the parylene and Au. The thickness of the device was 7 ± 1 μm, so the sensors attached easily to highly curved surfaces. The sensitivities of the temperature and humidity sensor were 4.81 × 10⁻³ °C⁻¹ and 0.03 pF/%RH, respectively. This work demonstrates the feasibility and compatibility of thin film sensor applications based on flexible parylene. The sensor can be applied to fuel cells or components that must be compressed.