This paper describes external camera-based shape estimation for continuum robots. Continuum robots have a continuous backbone made of sections which bend to produce changes of configuration. A major difficulty with continuum robots is the determination of the robot's shape, as there are no discrete joints. This paper presents a method for shape determination based on machine vision. Using an engineered environment and image processing from a high speed camera, shape determination of a continuum robot is achieved. Experimental results showing the effectiveness of the technique on our Elephant's Trunk Manipulator are presented.

In this paper the concept of a serial-parallel macro-milli manipulator is presented for medical applications by investigating the feasibility of combining two different robotic structures into one system. The combination of the two structures can be used as a redundant system in which stiffness, singularity and accuracy can be optimized as related to workspace demands and restrictions that are required for a priori selected medical applications. A case study has been experienced at LARM (Laboratory of Robotics and Mechatronics) at the University of Cassino through a new system composed of a commercial Adept COBRA and CaPaMan2bis (Cassino Parallel Manipulator 2bis). The performance of this system is compared with a previous serial-parallel macro-milli robotic system also developed at LARM in Cassino. Experimental tests have been carried out in order to characterize the proposed systems.

This paper presents a simplified kinematics propulsive model for carangiform propulsion. The carangiform motion is modeled as a serial $N$-joint oscillating mechanism that is composed of two basic components: the streamlined fish body represented by a planar spline curve and its lunate caudal tail by an oscillating foil. The speed of fish's straight swimming is adjusted by modulating the joint's oscillatory frequency, and its orientation is tuned by different joint's deflections. The experimental results showed that the proposed simplified propulsive model could be a viable candidate for application in aquatic swimming vehicles.

This paper proposes a general method to develop n-DOF serial isotropic manipulators. The parameters of 6-DOF isotropy generators are used as the initial values in a numerical method to obtain redundant isotropic generators. Additional constraint equations are then added, with the parameters of the obtained generators as initial values, to obtain the isotropy generators with special parameters. Each generator can be developed into many isotropic designs with special or desired link parameters. Two different approaches for developing isotropic manipulators are also investigated.

The paper introduces artificial neural networks for the conventional control of robotic systems for better tracking performance. Different advanced dynamic control techniques are explained and a new second order recursive algorithm has been developed to tune the weights of the neural network. The problem of real-time control of a Pendubot system in difficult situations has been addressed. Examples, such as positioning and balancing structures, are presented and performances are compared to a conventional PD controller.

This paper proposes an efficient algorithm for computing finger forces involved in a three-dimensional objects grasp. Effective finger force computation is necessary for the successful manipulation on an object by a multifingered robot hand. Based on previous works, the stability forces are computed as a solution of an optimization problem. This optimization problem is mapped into a linear quadratic problem under inequality constraints. We propose a new approach for this problem: the problem is solved as a minimal distance calculation problem in the forces space. The results obtained by simulation demonstrate the efficiency and the numerical stability of the method. This method is used with the LMS mechanical hand as a component of the global control strategy dedicated to the object manipulation.

This paper presents a design methodology to stabilize a class of multi-variant nonlinear system after a high disturbance occurs. It investigates application of Takagi-Sugeno type fuzzy controller (T-S-FC) to an inverted pendulum mechanism, actuated by an armature-controlled DC electrical motor.

Fuzzy controllers use heuristic information in developing design methodologies for control of non-linear dynamic systems. This approach eliminates the need for comprehensive knowledge and mathematical modeling of the system, and in cases of more complex systems, approximation and simplifications in order to achieve feasible mathematical model is not required.

The paper presents the stages of development of the Fuzzy Controller for an inverted pendulum by developing a two-input, Mamdani type system. It evaluates the performance of the system. Then a four-input T-S-FC type is developed. The research compares performances of each controller and presents the result of tests. A model for a DC motor is developed in this study, in order to measure the effect of time delays and response time caused by inherent properties of the physical system. The final part will demonstrate the complete operational system with the DC electrical motor included in the test system.

Motion coupling is one of the typical characters of parallel robots. This makes it complicated to control the parallel robots. Therefore, the design of parallel mechanisms with decoupled motions is an important and challenging issue in the parallel robotic field. However, research in this field, including the definition and type synthesis theory, is weak or lacking. In this paper, the reducible correlation between the input and the output of 3-DOF translational mechanisms with decoupled motions is investigated and the definition of this topic is presented. A new parameter named Gf coordinate is propsed for the synthesis of 3-DOF reducible translational mechanisms. The type synthesis theory for this kind of mechanisms is obtained and some reducible mechanisms are synthesized.

Most nonlinear control concepts used in robotics are based on a more or less accurate inverse model of the robot. In contrast to this, the design and properties of a general $n$-loop control structure based on a divided forward model of the robot, the so-called multi-loop Model Following Control Structure ($n$-MFC), is presented in this paper. Its theoretical basics and its concept are explained. The stability and robustness of the proposed control structure is analyzed. The theoretical assumptions are verified in many experiments with a two-joint robot manipulator. Qualitative as well as quantitative results of the experiments are presented and discussed.

In part I of this paper (previous issue of Robotica) a dual stage system with the coarse and fine actuators is adopted to achieve sub-micron accuracy with a large working space for the proposed new three degree-of-freedom (DOF) miniaturized micro parallel mechanism with high mobility and one type of the architecture with vertical actuator locations in all three legs (C-VV type) among six possible coarse actuator architectures is selected for the coarse actuator architecture.

In this part of the paper, an optimal kinematic parameter set is determined for the selected coarse actuator architecture. To determine this set, the design tool of the physical model of the solution space (PMSS) and the evaluation of the conditioning index (CI) and global mobility conditioning index (GMCI) are used. The basic size of the micro parallel mechanism is 45.0 mm×22.5 mm×22.9 mm with 100° mobility, the workspace 5.0 mm (y-axis)×5.0 mm (z-axis), and sub-micron resolution. After finishing the design of the main coarse actuator architecture, one architecture among six possible fine actuator architectures is selected to achieve sub-micron positioning accuracy based on the requirements of the continuous fine motion and smaller platform resolution. The selected coarse-and-fine actuator combination is used for the micro positioning platform for laser-machining application.

The complexity and uncertainty of the cross-sectional shape of the parts to be mated is one of the main reasons that misalignment between them occurs in assembly processes. Misalignment cannot only give rise to assembly failure but also cause damage to the parts or a robot due to large contact force. Therefore, misalignment sensing and compensation is essential for successful assembly operation. In this paper, we propose a novel misalignment estimation and compensation method which does not need any advance information on the cross-sectional shapes of the mating parts. This method utilizes a $\varphi-r$ transformation and an M-estimation pattern matching technique with misalignment images of a peg and a hole taken by an omni-directional visual sensing system during assembly. At every sampling instant during assembly action, it furnishes information on the relative position and orientation between the mating parts, and thus helps to estimate and compensate any possible misalignment between them. Also, a series of experiments are performed with a couple of peg-in-hole tasks, and the results are discussed. The experimental results show that the proposed method is effective for misalignment compensation in robotic assembly even though there is no prior information on part geometry and the images are very noisy.

For many biological creatures sensory whiskers are an effective means of detecting and recognising nearby objects. The project described in this paper has the aim of demonstrating that whisker sensors can be used as a similarly effective form of robot sensing. Many mobile robots have used whiskers as simple switches to warn of an imminent collision. However, these devices cannot provide the detailed surface profile information required to recognise and accurately locate objects. Several research groups have built advanced whisker sensors that can determine the position of a contact along the length of the whisker. Although these whisker sensors are usually little more than a length of flexible spring material they do require complex sensing and actuation mechanisms at the whisker root. In this project an array of eight whisker sensors is scanned over external objects by the motion of the robot. The resulting deflection of the whiskers is monitored by a potentiometer at each whisker root. By recording the deflection of the whiskers as they slide over external objects sequences of surface points can be determined. Object recognition algorithms have been developed that allow the robot to recognise, grasp and retrieve a range of objects using the whisker data. In this paper the robot, WhiskerBOT, is described together with the object recognition and localisation algorithms. Results of practical experiments are also presented.

In this paper an algorithm for real-time estimation of the position and orientation of a moving object using a video camera is presented. The algorithm is based on the extended Kalman filter which iteratively computes the object pose from the position measured in the image plane of a set of feature points of the object. A new technique is proposed for the selection of the optimal feature points based on the representation of the object geometry by means of a Binary Space Partitioning (BSP) tree. At each sample time, a visit algorithm of the tree allows pre-selecting all the feature points of the object that are visible from the camera in the pose predicted by the Kalman filter. A further selection is performed to find the optimal set of visible points to be used for image feature extraction. Experimental results are presented which confirm the feasibility and effectiveness of the proposed technique.

An ultra-precision integrated robotic system is developed, which integrates a passive robotic measurement system (shadow system) with an industrial robot. The shadow system is built almost ideal. In a working process, when the end-effecter of integrated robot is driven to a target with errors which are caused by degrading factors associated with the robot, the shadow system will independently detect the end-effecter frame instantly with ultra-precision kinematic accuracy. A scheme of approach control is then established to drive the end-effecter of the integrated robot to compensate the error step by step until the desired target is achieved with ultra-precision positioning accuracy.

This technical note deals with the way of organizing the work of a manipulator on a mobile robot. Every robotic mission is composed of several navigation and manipulation operations. In this research, the robot arm actions have been sequenced, once the mobile robot has stopped, with the help of the graphical specification tool Grafcet. The proposed method has been successfully implemented in the mobile manipulator RAM-2 for transporting videotapes.

For robotic manipulators that are redundant or with high degrees of freedom (dof), an analytical solution to the inverse kinematics is very difficult or impossible. Pioneer 2 robotic arm (P2Arm) is a recently developed and widely used 5-dof manipulator. There is no effective solution to its inverse kinematics to date. This paper presents a first complete analytical solution to the inverse kinematics of the P2Arm, which makes it possible to control the arm to any reachable position in an unstructured environment. The strategies developed in this paper could also be useful for solving the inverse kinematics problem of other types of robotic arms.

This paper describes a software tool to automate a design method for robotic fuzzy force control. The original method was developed to ensure robust and stable force control in situations where environmental stiffness at the robot/task interface is unknown, obviating the use of fixed-gain controllers. It did, however, involve a manual design process requiring significant knowledge of control theory and fuzzy logic. This process has been automated in the form of a Windows-based application, requiring minimal user inputs and incorporating an automatic tuning technique for improved performance in the final controller application. Results obtained from an experimental robot are presented.

This paper concerns the proposal and analysis of HANA, a novel spatial parallel manipulator with over constraint. The parallel manipulator consists of a base plate, a movable platform, and three connecting legs. The moving platform has three degrees of freedom (DoFs), which are two degrees of translational freedom and one degree of rotational freedom, with respect to the base plate. The new parallel manipulator is very interesting for the reason of a lack of singularity in its workspace, single-DoF joint architecture and high rotational capability of its moving platform. The inverse and forward kinematics problems are described in closed-forms. The velocity equation of the new parallel manipulator is given. Three kinds of singularities are presented. The workspace for the manipulator is analyzed systematically. Especially, the index to evaluate the rotational capability of the manipulator is defined and discussed in detail. The proposed manipulator has a wide application in the fields of industrial robots, simulators, micro-motion manipulators, and parallel kinematics machines.