Special End Effectors Research Articles

Autonomous Installation of Electrical Spacers on Power Lines Using Magnetic Localization and Special End Effector

The combined effects of environmental factors such as high winds and melting ice can cause transmission line conductors to vibrate at high amplitudes, resulting in damaged pole structures, cracked insulating strands, and short circuits. The manual installation of electrical spacers between the two power line conductors is currently the only way to prevent this, but due to the high-voltage environment, this operation is extremely dangerous for a human worker. As a solution to automate this operation, the autonomous installation of electrical spacers using a robotic manipulator is proposed. For this purpose, a design of a special end effector for the robotic installation of electrical spacers is proposed. The end effector prototype was produced and tested under laboratory conditions and then used for the autonomous installation of spacers on power lines. Its localization with respect to the power lines is based on measurements of the magnetic field generated by the alternating currents flowing through the power lines. To verify the feasibility of the proposed solution under laboratory conditions, the proposed end effector equipped with magnetometers was developed and mounted on a 6-axis Schunk LWA 4p robotic arm. The implemented autonomous installation sequence was successfully verified using a robot and a laboratory mock-up of power lines.

Design of a Wireless Drone Recharging Station and a Special Robot End Effector for Installation on a Power Line

Drone autonomous operations near power lines are growing steadily and require innovative techniques to keep them on air. This paper presents a novel electromechanical recharging station that can be mounted on energized AC power line to charge the drone battery wirelessly without a need to modify the electrical infrastructure. The work shows a thorough analysis of the electrical and mechanical core components to build a flexible, lightweight and efficient recharging station that can be attached to a robotic arm. The work also discusses the recharging station design and its special robot end effector that mechanically couples the station with an aerial manipulator. Finally, the recharging station has been tested in the lab and in a real power line setup to validate its design and efficiency. The total achieved mass is 2300 grams with a harvesting efficiency of 77% at 250 A primary current.

Development and Validation of an End-Effector for Mitigation of Collisions

Abstract In robotics, the risk of collisions is present both in industrial applications and in remote handling. If a collision occurs, the impact may damage both the robot and external equipment, which may result in successive imprecise robot tasks or line stops, reducing robot efficiency. As a result, appropriate collision avoidance algorithms should be used or, if it is not possible, the robot must be able to react to impacts reducing the contact forces. For this purpose, this paper focuses on the development of a special end-effector that can withstand impacts. It is able to protect the robot from impulsive forces caused by collisions of the end-effector, but it has no effect on possible collisions between the links and obstacles. The novel end-effector is based on a bi-stable mechanism that decouples the dynamics of the end-effector from the dynamics of the robot. The intrinsically nonlinear behavior of the end-effector is investigated with the aid of numerical simulations. The effect of design parameters and operating conditions are analyzed and the interaction between the functioning of the bi-stable mechanism and the control system is studied. In particular, the effect of the mechanism in different scenarios characterized by different robot velocities is shown. Results of numerical simulations assess the validity of the proposed end-effector, which can lead to large reductions in impact forces. Numerical results are validated by means of specific laboratory tests.

Design of a multi-arm concentric-tube robot system for transnasal surgery.

Concentric tube robot (CTR) has gradually attracted the attention of researchers on the basis of its small size and curved shape control ability. However, most of current experimental prototypes of CTR are single-arm structure, which can only carry out simple operation such as drug delivery or monitoring. In this paper, design and analysis of a three-arm CTR system is proposed. It has a four-DOF vision arm and two six-DOF manipulator arms, which equipped with special end effectors to achieve different surgical operations. Finally, a mean motion accuracy of 0.33 mm has been obtained quantitatively through teleoperation experiments. Moreover, tissue excision experiment in skull model is carried out to prove the effectiveness and feasibility of the proposed CTR system in nasopharyngeal carcinoma surgery. Graphical Abstract Platform of the proposed Multi-Arm Concentric Tube Robot system. (a) Configuration of the end-effectors with the CTR system. (b) The setup of the tissue removal experiment in a skull model.

Design of a Coupling/decoupling Mechanism of End Effector for a First Aid Robot’s Injection Function

This paper details the design of a special end effector that allows a first aid robot to quickly and accurately give an injection. There is growing demand for robots that can perform rescue operations on behalf of rescue workers in dangerous areas such as disasters or wars. The robots are primarily responsible for searching and transporting the injured, but they sometimes need to perform rescue activities after providing simple first aid at the site. Previous studies have proposed special end effectors that are suitable for onsite situations and enable robots to perform the given task quickly and accurately. This paper proposes a mechanism design for the injection device, a special end effector that would allow a robot performing first aid to give an injection to the injured. The proposed mechanism enables easy but strong coupling/decoupling of a medical auto-injector. Only a small amount of force needs to be exerted using the robot manipulator. Coupling is maintained by an exceptionally large force. Also, the optimal design value for the injection device joint was derived using mathematical analyses and experiments with the coupling structure.

A targeting method for robot-assisted percutaneous needle placement under fluoroscopy guidance.

Minimally invasive procedures are rapidly growing in popularity thanks to advancements in medical robots, visual navigation and space registration techniques. This paper presents a precise and efficient targeting method for robot-assisted percutaneous needle placement under C-arm fluoroscopy. A special end-effector was constructed to perform fluoroscopy calibration and robot to image-space registration simultaneously and automatically. In addition, formulations were given to compute the movement of robot targeting and evaluate targeting accuracy using only one X-ray image. A pre-clinical experiment showed that the maximum angle error was 0.94° and the maximum position error of a target located 80 mm below the end-effector was 1.31 mm. And evaluation of the system in a robot-assisted pedicle screws placement surgery has justified the accuracy and reliability of proposed method in clinical applications. The positioning accuracy was increased by using present method. Moreover, radiation exposure and operation time were reduced significantly compared to other commonly used methods.

A targeting method for robot-assisted percutaneous needle placement under fluoroscopy guidance

Minimally invasive procedures are rapidly growing in popularity thanks to advancements in medical robots, visual navigation and space registration techniques. This paper presents a precise and efficient targeting method for robot-assisted percutaneous needle placement under C-arm fluoroscopy. In this method, a special end-effector was constructed to perform fluoroscopy calibration and robot to image-space registration simultaneously. In addition, formulations were given to compute the movement of robot targeting and evaluate targeting accuracy using only one X-ray image. With these techniques, radiation exposure and operation time were reduced significantly compared to other commonly used methods. A pre-clinical experiment showed that the maximum angle error was 0.94° and the maximum position error of a target located 80mm below the end-effector was 1.31mm. And evaluation of the system in a robot-assisted pedicle screws placement surgery has justified the accuracy and reliability of proposed method in clinical applications.

Rapidly Exploring Random Tree Algorithm-Based Path Planning for Robot-Aided Optical Manipulation of Biological Cells

In numerous cellular applications, cells are transported to specific positions or extracted from complex cell solutions. Therefore, an efficient cell transportation path planner for these applications is important for avoiding collisions with other cells or obstacles. In this paper, a path planning approach to transporting cells using a robot-aided optical manipulation system is presented. Optical tweezers functions as a special end-effector in transporting a target cell to the desired position along the generated path. The path planner is designed based on the rapidly exploring random trees (RRT) algorithm for calculating a collision-free path for cell transportation. Both static and dynamic path planners are developed. For the dynamic path planner, an online monitoring strategy is employed to dynamically avoid collisions with randomly appeared obstacles caused by environmental influence such as the Brownian movement of microparticles. Experiments of transporting yeast cells are performed to demonstrate the effectiveness of the proposed approach. Note to Practitioners - Manipulations of cells and other microparticles represent an essential process for most cell-based bioengineering applications, such as cytopathology, cell sociology, and cytotaxonomy. Cell transportation, which is treated as a typical cell manipulation task, has recently received considerable attention because of its wide applications. This paper presents a novel approach to applying RRT-based path planner to cell transportation with a robot-aided optical manipulation system. The research outcome provides a unique solution to achieving cell transportation automatically and efficiently.

Automated Transportation of Single Cells Using Robot-Tweezer Manipulation System

Manipulation of biological cells becomes increasingly important in biomedical engineering to address challenge issues in cell-cell interaction, drug discovery, and tissue engineering. Significant demand for both accuracy and productivity in cell manipulation highlights the need for automated cell transportation with integrated robotics and micro/nano manipulation technologies. Optical tweezers, which use highly focused low-power laser beams to trap and manipulate particles at micro/nanoscale, have emerged as an essential tool for manipulating single cells. In this article, we propose to use a robot-tweezer manipulation system to solve the problem of automatic transportation of biological cells, where optical tweezers function as special robot end effectors. Dynamics equation of the cell in optical tweezers is analyzed. A closed-loop controller is designed for transporting and positioning cells. Experiments are performed on live cells to demonstrate the effectiveness of the proposed approach in effective cell positioning.

The jet experience with remote handling equipment and future prospects

The commissioning and testing of numerous pieces of equipment are now in progress at JET. Two microprocessor controlled force feedback MASCOT IV servomanipulators have shown comparable characteristics to those of the previous analogue types. Teach and repeat software permits precision welding and repetitive operations in a robotics mode. Other computer aids are planned to improve the man-machine interface: tool-weigth compensation, constraints along preferred lines or planes, automatic tracking of the TV cameras. The in-vessel transporter, provided with 5 vertical hinges, a pan-tilt-roll extension and special purpose end effectors, has been used under direct visual control to install 32 toroidal limiters and 8 radio frequency antennae. Tests of remote installation in teach and repeat were done, using the JET spare octant as a mock-up, achieving repeatability of better than 5mm. A considerable number of special remote handling tools were used inside the vessel hands-on to align, cut and weld diagnostics ports and water pipes. The cutting and welding trolleys were used hands-on, on a total of 250 m of lip joints. The ex-vessel transporter, a crane-mounted vertical telescope, 17 m high with a 10 m horizontal arm, is being manufactured. It will be equipped with manipulator and TV systems and controlled via joystick or keyboard or in teach and repeat. Image processing for collision avoidance is being studied. A low level transporter was used for turbo-pump replacement and is now being equipped with remote control. Mock-up work has started on the replacement of the Neutral Injector sources. Bench tests on flanges, heating jackets and connectors are being done to identify refinements needed. The in-vessel inspection system has been used at high temperature in vacuum.

An end effector for automatic assembly of seals by an industrial robot

Problems connected with the insertion of rubber seals in the internal grooves of hydraulic cylinders are presented, and functional specifications defined for a device oriented to automate insertion operations by the use of an industrial robot. A prototype is described, which consists of a special purpose end effector with three fingers, two of which can be moved in plane trajectories by stepper motors, so that they can grip and bend the seal to a particular shape and finally insert it, following clearly defined strategies. Test activity using a currently available industrial robot is described and future developments outlined.