Control of single-master multi-slave manipulator system using VIM

The authors propose an alternative coordinated motion control architecture for robot arms manipulating an object. The motion and the internal force of the object are resolved into the motion of each arm. Each arm is controlled, on the basis of the virtual internal model, so that they operate in coordination even if geometric errors exist in the arms and the object. The virtual internal model is a reference model driven by sensory information implemented in the controller. The proposed architecture maintains the stability of the system even if breakage of the manipulated object occurs. The control algorithm was experimentally applied to the coordinated motion control of two planar robot arms, each of which has three degrees of freedom. The results illustrate the validity of the proposed control architecture. >

Nowadays Industrial robots of different kinematic structures and functionality are widely used nowadays in different areas of industry and most of them function autonomously with preprogrammed set of actions or typical trajectories. Some special purposes mobile and stationary robots are human-controlled and in most cases require qualified operator skills. For example, in nuclear industry the mechanical and electro-mechanical “master arm – slave arm” manipulators are widely used. Modern approaches of control systems and human machine interfaces designs allow to eliminate direct copy of kinematic configuration of manipulator arms, add semi-automatic and automated control modes. Key feature of such manipulator systems is a presence of human in control loop, by reason of variety and complexity of manipulations and, in some cases, non-deterministic environment. Due to these factors, it is very desirable to form operator sustainable skills to control such manipulators, including learning process using training systems. This article describes general approaches and practical aspects of the operator training and qualification system for arm-based special purpose manipulators. The set of training system functions include: general manipulator control (basic motion) and grasping actions, manipulator operations in restricted working areas, operator actions using virtual reality helms and multi-monitor visualization, etc. The hardware and software architecture of training system should allow effective training process and teamwork of trainee and instructor to reach good results. The paper proposes ROS-based software part of training system with description of inter-process communication messages, data formats, integration with database and following analysis of trainee action.

In this paper, we consider wireless telerobotic systems and protocol development for low-delay wireless communication. Telerobotics can be defined as the control of robot arms from a remote location. In a telerobotic system, there is a robot arm to be controlled that is identified as the `slave arm', and a remote operator at a distant location using a robotic manipulator that is called the `master arm'. In the control system measurements, actuator delays do degrade the system's performance. Therefore, communication delays between the master and slave arms, and their minimization, are of extreme importance in telerobotics. In this paper, we first develop a new wireless communication protocol, the lightweight wireless protocol (LWP), designed on top of the 802.11 media access control layer. This low-delay wireless LWP protocol is implemented on an embedded system (AirDrop-LWP) without an operating system and its associated overhead. Finally, 2 AirDrop-LWP--embedded systems running this low-delay wireless LWP protocol are used to build a telerobotic system with a Mitsubishi RV-2AJ industrial robot. The LWP protocol is also tested on a robot car controlled by an AirDrop-LWP card as a slave arm and a standard PC as a master arm. The key features of the LWP are a reduced packet size, simple protocol stack, predictive compression of operator movements, and prediction of lost data packets. The LWP protocol is compared with the user datagram protocol and significant performance improvements are observed: a reduced delay of up to 50% and an additional 20% lower delay via compression. Variation in the packet delay times is also an important parameter for the wireless control system. As the standard deviation of the packet delay times increase, and becomes less and less predictable, the resulting telerobotic system will be more and more difficult to operate. We measured the standard deviation of packet delays and observed that it increases with the packet size, and this increase is faster than the increase in mean packet delay.

An electric master-slave manipulator was generally used for remote control systems. Generally, the master arm has the same mechanism as the slave arm. Thus, the operator is constrained by the master arm. From such a point of view, a nonconstrained master arm with tactile feedback actuator was developed. The operator can move without constraint and feel the force or touch between slave and objects. If a tactile feedback actuator on a master arm is made from mechanical actuator, it will constrain the operator. Thus, a pneumatic balloon actuator was developed to return the touch between the slave arm and objects to the master arm. The system was experimentally produced and its performance tested and evaluated. It was found to be applicable to a nonconstrained master arm with tactile feedback actuator.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The servicing aid tool (SAT) is a teleoperated manipulation system designed for use on the NSTS Orbiter. The system will assist EVA servicing of spacecraft such as the Hubble Space Telescope and Explorer platform. SAT components are spaceflight adaptations of existing ground-based designs from Robotics Research and Schilling Development. Fairchild Space is providing the control electronics, safety system, and flight integration. The manipulator consists of a 6-DOF slave arm mounted on a 1-DOF positioning link in the payload bay. The slave arm is controlled via a highly similar, 6-DOF, force-reflecting master arm. Each slave arm joint receives position commands from the corresponding master arm joint; torque commands are reflected to each master joint based on the current state of the slave joint and the master/slave relationship. Scaled and indexed control will be accommodated, as will various features to ensure safe operation. The paper focuses on the development of the safety system, and operations for the demonstration and servicing missions.

In the existing master-slave system, the design of the control parameters is performed in the heuristics, and veteran designers and workers are needed. In this paper, we aimed to realize the ideal behavior for each person more easily, devised a method incorporating DeepQ-Network (DQN) in the virtual internal model. As a result of verifying the method using simulation, we could not realize master - slave control. but could show the learning possibility of the model.

Minimally invasive surgery (MIS) which thinks a great deal of patient’s quality of life (QOL) has attracted attention during about ten years. In this paper, it aims at development of the technology for transmitting force sensation required in medical treatment especially through surgical instruments, such as forceps. In bilateral control, it is a problem how master and slave robots realize the law of action and reaction to the environment. Mechanism of contact with environment and bilateral controller based on stiffness are shown. Master arm in contact with human and slave arm in contact with environment are given compliance, and stable contact with environment can be realized. The proposed method is applied to 3-link master-slave manipulators. As a result, transmission and reproduction of force sensation can be realized. The experimental results show viability of the proposed method.

Advances in technology have expanded the use of soft actuators in various fields especially in robotics, rehabilitation and medical field. Soft actuator development provides many advantages, primarily being simple structures, high power to weight ratio, good compliance, high water resistance and low production cost. However, most soft actuators suffer the problem of being oversized which could potentially hurt users as it is often made of hard materials such as steels and hard rigid plastics. Current drawbacks of soft actuator implementation in robotic arms are on its excessive weights, causing these robots to be difficult to set up by patients themselves which in turn makes it less applicable for home rehabilitation training program. Hence, there is a need to design a soft actuator which is safe and more flexible, especially for applications in areas of patients in rehabilitation area or in-house rehabilitation program. In this paper, we propose the design of robot arm using master device pneumatic actuator and analyse the implementation for the above purpose. The system comprises primarily of the master and slave arms, two accelerometers and two potentiometers providing references for attitude control, six quasi-servo valves, and SH-7125 microcontroller. Our proposed design exhibits functions of the actuator that has been generated from elastic deformation of extension and contraction of the cylinder structure when high pneumatic pressure is supplied to the chamber. The control performance of the device is investigated using simulation method, whereby the rational model of the robot arm and the quasi servo valve with the embedded controller is implemented and analysed. It is found that the analysed results of the model approved well with the desired values.

Design Fundamentals of Master-Slave Systems with a Force-Position Bilateral Control Scheme

In recent years the disappointment about the very slow progress in the area of sensor-based robot intelligence and autonomy has led to an increasing interest in master-slave systems. This teleoperational solution-developed by the Department of Mechanical Engineering of Banki Donat Polytechnic-is based on 6D force reflection. The joystick-like master arm with the hydraulic force percolation generated by the executive mechanism, connects the signal from the force perceptors and proceeding electronics to the controller of the proportional valves. The proportional valves transmit proportional pressure with the force generated at the final point of the manipulator to the force feeling valves of the master arm. The system also supplies the ability to select the force feeling and also the actuator control by degrees of freedom, but the force reflection can be stopped at any time by the operator. The force is visualised by a digital display. This paper is an overview of the master-slave development.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Trabecular bone microdamage significantly influences the skeletal integrity and bone remodelling process. In this paper a novel constitutive model, called the virtual internal bond model (VIB), was adopted for simulating the damage behaviour of bone tissue. A unique 3D image analysis technique, named individual trabeculae segmentation, was used to analyse the effects of microarchitectures on the damage behaviours of trabecular bone. We demonstrated that the process of initiation and accumulation of microdamage in trabecular bone samples can be captured by the VIB-embedded finite-element method simulation without a separate fracture criterion. Our simulation results showed that the microdamage can occur at as early as about 0.2–0.4% apparent strain, and a large volume of microdamage was accumulated around the apparent yield strain. In addition we found that the plate-like trabeculae, especially the longitudinal ones, take crucial roles in the microdamage behaviours of trabecular bone.

It is evident that biocomposites, specifically mineralized Type-I collagen fibrils, have strong mechanical properties, such as a desirable combination of elastic modulus, fracture toughness, and fracture strength. The mineral Hydroxyapatite [Hap] by itself is stiffer, and it is not clear whether a collagen fiber by itself has a lower breaking strength than the mineralized fiber. Hence, the objective of this paper is to develop, outline, apply, and demonstrate issues involving a new nano explicit finite element based framework, by which the mechanical behavior of mineralized collagen fibrils and their constituents can be studied. A multi-scale virtual internal bond model is used to model the material behavior and failure of such biocomposites. In this research two models have been studied. The first model attempts to illustrate the hypothesis that materials are less sensitive to flaws at nanoscale and the second model studies the mechanical behavior of a nano sized dahlite mineral crystal commonly found in collagen fibril. Two important implementation characteristics have been introduced and illustrated, namely that scaled properties can be used at the micro and nano length scales along with scaled dimensions and secondly the loading time can be appropriately scaled without the loading becoming a dynamic loading.

Finite element implementation of virtual internal bond model for simulating crack behavior

An assessment of industrial robots: Capabilities, economics, and impacts

Myoelectric bionic limbs hold the promise of restoring functionality and improving life quality for people with amputation. With recent advances in surgical reconstruction, which created additional signal sites for myoelectric control, intuitively controlling all fingers of a prosthetic hand became a possibility. To fully utilize a multiple degree of freedom (DoF) bionic hand, the fingers need to be controllable both individually and simultaneously. However, training algorithms to decode motor intent typically requires large sets of labeled data. This data requirement grows combinatorically with each additional DoF, complicating the training process for multi-DoF control. Here, we evaluated a method to create labeled simultaneous data from linearly combining individual movement data. We found that a classifier trained on such artificial data performed equivalently in decoding 3 DoF real-time finger movement to a classifier trained on ground truth data. However, its effectiveness diminishes with more complex tasks, i.e., 5 DoF finger control. In both cases, linearly combining individual movements decreased the time to acquire labeled data to train the classifier by up to 85%.