A CNN-based chip for robot locomotion control

In this paper, the paradigm of emergent computation is applied to locomotion control in legged robots: the locomotion gait is the result of self-organization of a network of locally coupled nonlinear oscillators. This means to adopt the biological paradigm of central pattern generator (CPG), implemented by using cellular neural networks (CNNs). The whole control strategy is hybrid in the sense that the gait generation is accomplished by a fully analog CNN, while a simple logic unit modulates the behavior of the CNN-based CPG, so that the strategy is suitable to eventually include sensory feedback. The design of a VLSI chip implementing the CNN-based CPG and some experimental results on the chip are presented. The chip is designed using a switched-capacitor technique, fundamental to obtain in a simple and direct way some key features of the hybrid control discussed. The experimental results confirm the suitability of the approach.     

CPG-based control of serpentine locomotion of a snake-like robot

In this paper, a biomimetic approach is proposed to solve the difficulty in control of a snake-like robot with a large number of degrees of freedom. This method is based on the central pattern generator (CPG), which is a rhythmical motion generator existing in most animals. Compared with the previous research, a new network with feedback connection is presented, which can generate uniform outputs without any adjustment. Furthermore, the relation characteristics between the CPG parameters and the outputs are investigated. Both simulation and experiment of the snake-like robot have been taken for the analysis of the locomotion control. Desired locomotion patterns can be achieved by adjusting the CPG parameters correspondingly from the results.     

Articulated hybrid mobile robot mechanism with compounded mobility and manipulation and on-board wireless sensor/actuator control interfaces

This paper presents the development of a remotely operated mobile robot system with a hybrid mechanism whereby the locomotion platform and manipulator arm are designed as one entity to support both locomotion and manipulation interchangeably. The mechanical design is briefly described as well as the dynamic simulations used to analyze the robot mobility and functionality. As part of the development, this paper mainly focuses on a new generalized control hardware architecture based on embedded on-board wireless communication network between the robot’s subsystems. This approach results in a modular control hardware architecture since no wire connections are used between the actuators and sensors in each of the mobile robot subsystems and also provides operational fault-tolerance. The effectiveness of this approach is experimentally demonstrated and validated by implementing it in the hybrid mobile robot system. The new control hardware architecture and mechanical design demonstrate the qualitative and quantitative performance improvements of the mobile robot in terms of the new locomotion and manipulation capabilities it provides. Experimental results are presented to demonstrate new operative tasks that the robot was able to accomplish, such as traversing challenging obstacles, and manipulating objects of various capacities; functions often required in various challenging applications, such as search and rescue missions, hazardous site inspections, and planetary explorations.     

Design and control of robot manipulator with a distributed actuation mechanism

This paper presents a design methodology based on the distributed actuation principle to achieve a high-performance robot manipulator. Spatial movement of the actuation points provides several advantages such as high payload capacity, high efficiency and a light weight structure for the proposed robot manipulator. Based on the analysis, the distributed actuation mechanism using a single slider is adopted for the proposed manipulator. A prototype of the manipulator with two degrees of freedom is developed and controlled as an example. The efficacy of the proposed approach is verified experimentally.     

Generalized impedance control of robot for assembly tasks requiringcompliant manipulation

To perform assembly tasks requiring compliant manipulation, the robot must follow a motion trajectory and exert an appropriate force profile while making compliant contact with a dynamic environment. For this purpose, a generalized impedance in the task space consisting of a second-order function relating the motion errors and interaction force errors is introduced such that the contact force can be commanded and controlled. With generalized impedance control, the robot can behave with a desired dynamic characteristic when it interacts with the environment. To ensure the success of the assembly, a strategy during task planning which takes into consideration the interrelation between motion and force trajectories as well as contact compliance is introduced. The generalized impedance control method is applied to the prismatic joint of a selective compliance assembly robot arm (SCARA) robot for inserting a printed circuit board (PCB) into an edge connector socket. Depending on the progress of the parts joining operation, various amount of interaction forces are generated which have to be accommodated. It is demonstrated that an assembly strategy which consists of a sequence of carefully planned target impedance can enable the task to be executed in a desirable manner. The effectiveness of this approach is illustrated through experiments by comparing the results with those obtained using a well-established position control scheme as well as the original impedance control method     

Optimization of a spherical mechanism for a minimally invasive surgical robot: theoretical and experimental approaches

With a focus on design methodology for developing a compact and lightweight minimally invasive surgery (MIS) robot manipulator, the goal of this study is progress toward a next-generation surgical robot system that will help surgeons deliver healthcare more effectively. Based on an extensive database of in-vivo surgical measurements, the workspace requirements were clearly defined. The pivot point constraint in MIS makes the spherical manipulator a natural candidate. An experimental evaluation process helped to more clearly understand the application and limitations of the spherical mechanism as an MIS robot manipulator. The best configuration consists of two serial manipulators in order to avoid collision problems. A complete kinematic analysis and optimization incorporating the requirements for MIS was performed to find the optimal link lengths of the manipulator. The results show that for the serial spherical 2-link manipulator used to guide the surgical tool, the optimal link lengths (angles) are (60 degrees, 50 degrees). A prototype 6-DOF surgical robot has been developed and will be the subject of further study.     

EA-HD: a novel link state update mechanism for ASON

When a connection request comes in a mesh optical network, the routers automatically choose the suitable routing paths and wavelength to it according to the network topology and link-state information saved in its global link-state database. Because some of these wavelengths may be released or occupied at any time, the global state database is always out of date and need update by some update policy. A suitable link-state update policy is critical, since a high-frequency update policy imposes heavy burden on the network, while a low-frequency update would increase the inaccurate of the global link-state database. In this paper, we propose a link-state update policy, named the EA-HD policy, which considers two index of a link, one is the Hamming distance between the local link-state database and the global link-state database, and the other is the used ratio of its wavelengths. The proposed update policy gets a trade-off between the accurate of link-state information and its update cost. Simulation results prove that our scheme achieves a good performance in traffic blocking probability while maintaining moderate volume of update traffic.     

Characteristic analysis of a novel in-pipe driving robot

Gas and liquid pipelines are all around us in today’s society. The frequent inspection and maintenance of such pipeline grids is very important, especially for urban areas where there are dense populations. Many driving mechanisms for in-pipe crawling have been reported in previous studies. In this paper, a novel in-pipe drive design is presented. The proposed design uses modular helical drives. In between helical drives is a conic coil spring that allows extension and retraction. Since conic springs can be designed with telescopic feature, the proposed design can be made very compact. Furthermore, the proposed design also has much better mobility when turning a bend due to its flexible body (conic springs make the inchworm robot a compliant mechanism). The proposed design can be controlled with three modes of motion: synchronized motion (for small load), inchworm motion (for medium load), and rigid motion (for heavy load). Analysis on gripping force, locomotion force, together with experimental results will be presented as well.     

Ultra-lightweight anthropomorphic dual-arm rolling robot for dexterous manipulation tasks on linear infrastructures: A self-stabilizing system

This paper proposes the application of a very low weight (3.2 kg) anthropomorphic dual-arm system capable of rolling along linear infrastructures such as power lines to perform dexterous and bimanual manipulation tasks like the installation of clip-type bird flight diverters or conduct contact-based inspection operations on pipelines to detect corrosion or leaks. The kinematic configuration of the arms, with three joints at the shoulder and one at the elbow, allows the natural replication of the human movements to conduct these tasks, exploiting also the kinematic redundancy of the shoulder to maintain the equilibrium while perching on the line. The dynamic model of the system is derived to design a self-stabilizing controller that maintains the base of the arms at an equilibrium point. The state-dependent Riccati equation (SDRE) controller is chosen for this purpose since the system is under-actuated and the contribution of the control gain (with nonlinear optimal structure) on all states is critical. The SDRE is a nonlinear optimal controller that extends the margins of stability in comparison with linear ones. Simulation results show that the SDRE performs the regulation to the equilibrium point successfully and evidence better performance with respect to a linear quadratic regulator (LQR). The system is validated in an outdoor testbed consisting of a power line mockup, presenting experimental results to evaluate the SDRE and LQR controllers, demonstrating also the autonomous installation of clip-type bird flight diverters and the aerial deployment using a multirotor platform.     

Development of a parallel wire mechanism for measuring position and orientation of a robot end-effector

This paper presents a parallel wire mechanism developed for measuring six degrees of freedom of a robot end-effector. The mechanism consists of six parallel wire links. The position and orientation of a robot are obtained from the wire lengths measured in the parallel wire mechanism. The complex nonlinear equations of the forward kinematics are solved by using a Newton–Raphson method, and a unique solution is determined from the geometric configuration of the developed mechanism. The wire length error caused by longitudinal deformation of the wires is compensated by a wire compensation factor. Through the experiment, it is verified that the developed mechanism has an accuracy of ±0.05 mm, ±0.1° in the position and the orientation, respectively. The developed parallel wire mechanism can be used effectively for measuring the position and orientation of a six degree of freedom (DOF) of robot end-effector with low cost and effort.     

Development of a novel compact hydraulic power unit for the exoskeleton robot

Exoskeleton robots require powerful and lightweight power supplies. Because of its high power-to-mass ratio and fast response, hydraulic systems can meet the requirement for locomotion robots. In this paper, a novel compact hydraulic power unit (CHPU) is proposed. A two-stroke IC engine, with a rated power of 2.4 kW at 13,000 rpm, is used as the prime mover. The engine drives a high speed (10,000 rpm) piston pump to allow the engine to operate at high power. A spring loaded reservoir has been developed to prevent the pump intake from cavitation and contamination. The payload flow rate is indirectly estimated using the displacements of the actuator. A Ragone plot analysis shows that the CHPU can maintain a high specific power over a long duration. A dynamic model for the CHPU has been developed based upon simplified engine operating characteristics and a set of experimentally identified parameters. A prototype of the CHPU has been constructed with a rated power of 1.45 kW and a weight of 16.6 kg. Experimental testing of the prototype confirms the dynamic model and the output capacity of the CHPU.     

新型机器人视觉系统准直相干光束的获取

论述了一种新型的机器人视觉系统所用激光准直光束的获取方法，分析了半导体激光束的像散椭圆高斯光束特性，设计了光束准直系统的光学结构，利用光斑法对准直度进行了检验。实验证明利用这种方法获取的直光束符合该视觉系统的要求。     

Hybrid electrostatic and elastomer adhesion mechanism for wall climbing robot

In this paper a hybrid solution to the problem of robots climbing on featureless surface is presented. The research focus of wall climbing robot is on the adhesion and the mechanism of locomotion. An efficient, robust, standalone and scalable mechanism is often desired for such robots to perform many critical tasks. The performance of electrostatic adhesion can be enhanced by using flexible and soft elastic material as the dielectric to improve its resistance against peeling force. A novel multiple stage fabrication process of the layered hybrid adhesive using blade coating technique is proposed in this work. This yields a track structure that is compliant on the surface, electrically functional, and geometrically controllable. When excited by high voltage, the track becomes an active actuator. It also passively adheres to smooth surfaces with the elastomer effect. Inspired by the climbing strategy of the gecko, a solution for track locomotion is proposed by utilizing electrostatic, elastomer adhesion and tail forces simultaneously. The biomimetic tail is implemented with torsion spring design. As a result, the robot prototype ELAD (electrostatic and elastomer adhesion) can climb a slope of 80° on smooth surfaces at speed of 4 cm/s, and perch for more than 2 h using on-board power. Effects of tail design and hybrid adhesion with force analysis are numerically evaluated and presented. It is also demonstrated that the elastomer material properties for the hybrid adhesive are suitable for stable climb on vertical surfaces. Further, analysis has shown that the hybrid adhesive is able to work on surfaces with roughness value Ra within 300 nm.     

Design and dynamics of a 3-DOF flexure-based parallel mechanism for micro/nano manipulation

This paper presents the mechanical design and dynamics of a 3-DOF (degree of freedom) flexure-based parallel mechanism. Flexure hinges are used as the revolute joints to provide smooth and high accurate motion with nanometer level resolution. Three piezoelectric actuators are utilized to drive active links of the flexure-based mechanism. The inverse dynamics of the proposed mechanism is established by simplifying flexure hinges into ideal revolute joints with constant torsional stiffnesses. Finite element analysis is used to validate the performance of the proposed 3-DOF flexure-based parallel mechanism. The interaction between the actuators and the flexure-based mechanism is extensively investigated based on the established model. Experiments are carried out to verify the dynamic performance of the 3-DOF flexure-based mechanism.     

Conditions for worm-robot locomotion in a flexible environment: theory and experiments

Biological vessels are characterized by their substantial compliance and low friction that present a major challenge for crawling robots for minimally invasive medical procedures. Quite a number of studies considered the design and construction of crawling robots; however, very few focused on the interaction between the robots and the flexible environment. In a previous study, we derived the analytical efficiency of worm locomotion as a function of the number of cells, friction coefficients, normal forces, and local (contact) tangential compliance. In this paper, we introduce the structural effects of environment compliance, generalize our previous analysis to include dynamic and static coefficients of friction, determine the conditions of locomotion as function of the external resisting forces, and experimentally validate our previous and newly obtained theoretical results. Our experimental setup consists of worm robot prototypes, flexible interfaces with known compliance and a Vicon motion capture system to measure the robot positioning. Separate experiments were conducted to measure the tangential compliance of the contact interface that is required for computing the analytical efficiency. The validation experiments were performed for both types of compliant conditions, local and structural, and the results are shown to be in clear match with the theoretical predictions. Specifically, the convergence of the tangential deflections to an arithmetic series and the partial and overall loss of locomotion verify the theoretical predictions.     

A novel robotic colonoscopy system integrating feeding and steering mechanisms with self-propelled paddling locomotion: A pilot study

Colonoscopy is a common procedure to perform advanced therapies such as Endoscopic Submucosal Dissection (ESD), which allows for greater diagnostic specificity and sensitivity compared to other types of examination. Nevertheless, since the colonoscope can cause patient discomfort or pain due to improper manipulation, it is quite challenging for endoscopists who need to develop the necessary skills to accurately perform the procedure and minimize this discomfort. To overcome these sorts of limitations inherent in conventional colonoscopies, various studies regarding robotic and automated systems have been made. In this paper, based on the mechanics of paddling locomotion, a fully self-propelled robotic colonoscope is proposed, then integrated with assistance modules. The feeding and the steering module aim to assist the navigation of the human colon. By building on operations already familiar to endoscopists (i.e., tip deflection, push forward and pull back, hooking, etc.), the device's automatic sequences are investigated to ensure high safety and maneuverability. In addition, a Multimodal Robotic Colonoscope Interface (MRCI) is integrated with each modular mechanism, which allows endoscopists to monitor kinetic/kinematic data and implement manual control in case of unexpected emergency (i.e., deadlocked in colon, paradoxical movement, etc.). With the integrated interface, a pilot study using a porcine colon was conducted. Through an In-vitro test along a straight path, the velocity of the proposed RC was identified as 16.9 mm/s at a paddling frequency of 2 Hz with feeding force of 10 N. These results are 1.7 times faster (9.6 mm/s) than tests that only used paddling locomotion without any feeding force and steered angle. Furthermore, at a curved path with a radius of 60 mm, the RC velocity was measured at 21.5 mm/s, and experienced a radial elongation ratio of 20%. Similarly, at an inclined path of 30°, the velocity of the robot increased 25% (8.93 mm/s) compared to paddling locomotion alone (7.14 mm/s). The final results showed that the integrated system had superior results compared to previous studies based on self-propelled locomotion alone.     

Design and development of a novel type of table tennis aerial robot player with tilting propellers

Table tennis has long fascinated roboticists as a particularly difficult task which requires fast movements, accurate control and adaptation to task parameters. In addition, the development of such devices is useful for educating the undergraduate students. Up to now, several groups have developed robotic manipulators playing table tennis and other commercial interactive robots. Moreover, drones are booming right now, and they can cover a larger workspace than manipulators, for a lower device volume and at a lower price. In this context, this paper aims to propose a drone playing table tennis to analyze the benefits and the disadvantages for this task. Most vertical takeoff and landing (VTOL) vehicles are not fast enough to reproduce hitting motions. The proposed prototype is an innovative quadrotor combining a tilting propeller and a state-dependent iterative linear quadratic control (iLQR). The performance of the proposed solution is evaluated with real experiments that show the success of the approach, reaching hitting rates of 40%.     

新型混联式涂装输送机构的PD滑模控制

针对一种新型混联式汽车电泳涂装输送机构,为解决滑模控制过分依赖于动力学模型的问题、弥补传统PD控制在强耦合强非线性系统中存在的不足,采用时延估计技术对动力学模型进行线性化处理,据此设计一种线性化PD滑模控制器。首先采用拉格朗日法建立机构的动力学模型,然后针对采用时延估计技术线性化的动力学模型设计滑模控制器,同时把时延估计误差作为扰动处理,通过PD控制保证系统的全局渐定稳定。其次,运用Lyapunov稳定性理论证明了所提出控制算法的稳定性,为PD滑模控制律参数的选择提供了准则。最后,分别对滑模控制和PD滑模控制进行MATLAB仿真比较。结果表明,所提出的PD滑模控制方法不仅使系统获得更好的跟踪性能,而且结构简单、易于实现、计算量小,从而实现对新型混联式汽车电泳涂装输送机构的高性能跟踪控制。     

Early detection and prevention of denial-of-service attacks: a novel mechanism with propagated traced-back attack blocking

A major threat to the information economy is denial-of-service (DoS) attacks. These attacks are highly prevalent despite the widespread deployment of perimeter-based countermeasures. Therefore, more effective approaches are required to counter the threat. This requirement has motivated us to propose a novel, distributed, and scalable mechanism for effective early detection and prevention of DoS attacks at the router level within a network infrastructure. This paper presents the design details of the new mechanism. Specifically, this paper shows how the mechanism combines both stateful and stateless signatures to provide early detection of DoS attacks and, therefore, protect the enterprise network. More importantly, this paper discusses how a domain-based approach to an attack response is used by the mechanism to block attack traffic. This novel approach enables the blockage of an attack to be gradually propagated only through affected domains toward the attack sources. As a result, the attack is eventually confined within its source domains, thus avoiding wasteful attack traffic overloading the network infrastructure. This approach also provides a natural way of tracing back the attack sources, without requiring the use of specific trace-back techniques and additional resources for their implementation.     

EHM: a novel efficient protocol based handshaking mechanism for underwater acoustic sensor networks

Underwater Media Access Control (MAC) protocol design faces more challenges due to the unique characteristics of acoustic communication such as the long propagation delay and limited bandwidth. The long propagation delay in underwater causes the hidden terminal and spatially unfair problem. In this paper, we propose an efficient MAC protocol for multi-hop underwater acoustic sensor networks, which we shall call the EHM—Efficient Handshaking Mechanism. It is a handshaking-based protocol that addresses the hidden terminal and spatially unfair problem, and the EHM protocol can improve the channel utilization by allowing a node to receive data packets from multiple potential senders simultaneously. This method can reduce the relative proportion of time spent on control packets. The performance of the proposed protocol is evaluated via simulations. Experiment results show that the EHM protocol outperforms in channel utilization, fairness of transmission and end-to-end packets delay.