DOF Robotic Arm Research Articles

Improvement of the joint range for 5-DOF robot arm with parallel link mechanism

Improvement of the joint range for 5-DOF robot arm with parallel link mechanism

DEVELOPMENT OF 5 DOF ROBOTIC ARM PROTOTYPE CONTROL SYSTEM IN BRACHYTHERAPY PREPARATION BASED ON ARTIFICIAL NEURAL NETWORK

Brachytherapy is a cancer treatment that uses radioactive sources with temporary or permanent implantation in cancer tissue. The theraphy uses a radioactive Ir-192 source wrapped in a stainless steel capsule with a diameter of 0.5 mm and a length of 4 mm. The Center for Radioisotopes and Radiopharmaceutical Technology applies a remote manipulator to manufacture microcapsules, which affects the accuracy and risks of the radiation received by the operator. Therefore, to solve this problem, it is necessary to design a 5 DoF robotic arm based on artificial neural networks as a radioactive source transfer tool to improve the precision and safety of operators in preparing the radioactive sources. In developing the 5 DoF robotic arm control system, the NImyRIO was employed, which can control the servo motor, relay pump and valve reality, image processing, and inverse kinematic. The inverse kinematic uses the neural network method with a forward kinematic validation. The inverse kinematic test obtains the RMSE value of 2.78932 for x, 5.05205 for y, and 12.641 for z in the inverse kinematic test of artificial neural networks. Therefore, the inverse kinematic accuracy of the artificial neural network needs to be redeveloped.

Automatic interpolation algorithm for NURBS trajectory of shoe sole spraying based on 7-DOF robot

PurposeThe purpose of this paper is to propose an automatic interpolation algorithm for robot spraying trajectories based on cubic Non-Uniform Rational B-Splines (NURBS) curves, to solve the problem of sparse and incomplete trajectory points of the head and heel of the shoe sole when extracting robot motion trajectories using structured-light 3D cameras and to ensure the robot joints move smoothly, so as to achieve a good effect of automatic spraying of the shoe sole with a 7-degree-of-freedom (DOF) robot.Design/methodology/approachFirstly, the original shoe sole edge trajectory position points acquired by the 3D camera are fitted with NURBS curves. Then, the velocity constraint at the local maximum of the trajectory curvature is used as the reference for curve segmentation and S-shaped acceleration and deceleration planning. Immediately, real-time interpolation is performed in the time domain to obtain the position and orientation of each point of the robot motion trajectory. Finally, the inverse kinematics of the anthropomorphic motion of the 7-DOF robot arm is used to obtain the joint motion trajectory.FindingsThe simulation and experiment prove that the shoe sole spraying trajectory is complete, the spraying effect is good and the robot joint movement is smooth, which show that the algorithm is feasible.Originality/valueThis study is of good practical value for improving the quality of automated shoe sole spraying, and it has wide applicability for different shoe sole shapes.

Automatic Robot-Driven 3D Reconstruction System for Chronic Wounds.

Chronic wounds, or wounds that are not healing properly, are a worldwide health problem that affect the global economy and population. Alongside with aging of the population, increasing obesity and diabetes patients, we can assume that costs of chronic wound healing will be even higher. Wound assessment should be fast and accurate in order to reduce the possible complications, and therefore shorten the wound healing process. Contact methods often used by medical experts have drawbacks that are easily overcome by non-contact methods like image analysis, where wound analysis is fully or partially automated. This paper describes an automatic wound recording system build upon 7 DoF robot arm with attached RGB-D camera and high precision 3D scanner. The developed system presents a novel NBV algorithm that utilizes surface-based approach based on surface point density and discontinuity detection. The system was evaluated on multiple wounds located on medical models as well as on real patents recorded in clinical medical center.

HARMONIC: A multimodal dataset of assistive human–robot collaboration

We present the Human And Robot Multimodal Observations of Natural Interactive Collaboration (HARMONIC) dataset. This is a large multimodal dataset of human interactions with a robotic arm in a shared autonomy setting designed to imitate assistive eating. The dataset provides human, robot, and environmental data views of 24 different people engaged in an assistive eating task with a 6-degree-of-freedom (6-DOF) robot arm. From each participant, we recorded video of both eyes, egocentric video from a head-mounted camera, joystick commands, electromyography from the forearm used to operate the joystick, third-person stereo video, and the joint positions of the 6-DOF robot arm. Also included are several features that come as a direct result of these recordings, such as eye gaze projected onto the egocentric video, body pose, hand pose, and facial keypoints. These data streams were collected specifically because they have been shown to be closely related to human mental states and intention. This dataset could be of interest to researchers studying intention prediction, human mental state modeling, and shared autonomy. Data streams are provided in a variety of formats such as video and human-readable CSV and YAML files.

Design of a Biomimetic BLDC Driven Robotic Arm for Teleoperation & Biomedical Applications

For many years, robotics research and development has been held back from the high-power AC motors of industrial automation, locked to low-power, bulky Stepper motors and simple DC Servos. As of a few years ago, Brushless DC motors started seeing use in high-end quadrupedal designs such as Boston Dynamics Cheetah, and Spot. Whilst these used expensive, proprietary control systems that were closed source and out of the reach of many small-scale researchers, developers, and hobbyists, they did demonstrate the potential of a motor-class previously only commonly thought suitable for high-RPM applications like drones and quadcopters. In 2016, an open-source custom driver platform named ODrive was started, which is now in its 3rd iteration. As of 2021, it provides all of the basic hardware and software needed to control 2 closed loop Brushless DC motors per board, using off the shelf encoders and at a reasonable, hobbyist level price point. This technology is, on paper, a huge development for plenty of low-budget robotics research applications. In this project, we design, build, and evaluate a 4 DOF robotic arm using 4 BLDC motors with ODrive control, using 3D printed parts and other components available at a low price point. This arm will be used in the future for testing tele-operative control and so it is designed to be biomimetic, modelled at 2/3 scale with similar proportions and motion capabilities to a real human arm to the elbow. The extremely small, cheap, and lightweight motors selected for this project are shown to output superior speed and torque to stepper motors multiple times their size and weight, albeit at a very significant power draw requirement. The speed and power of a BLDC through a high reduction gearbox allows extremely fast and responsive movement such that it can easily execute complex movements easily in pace with a human arm. Doi: 10.28991/HEF-2021-02-04-03 Full Text: PDF

A novel hand exoskeleton to enhance fingers motion for tele-operation of a robot gripper with force feedback☆

This research describes a robotic system's design, optimization, and implementation processes for tele-operation with haptic feedback using the Hand Exoskeleton of New technologies research center (HEXON) as a novel haptic mechanism and the HEXON robotic gripper to work collaboratively with the exoskeleton. In particular, a force-sensitive robotic gripper is connected to a hand exoskeleton, mimics the user's hand movements, and transfers haptic feedback through the exoskeleton. The two-finger exoskeleton's design process consists of a multi-criteria optimization procedure to simultaneously maximize applied force to the finger and workspace of the attached exoskeleton, optimizing both the Perpendicular Impact Force (PIF) and the Global Isotropy Index (GII), considering worst-case collision avoidance. Due to the tele-operation application and using a robotic arm as a slave in the remote scenario, the gripper can be used as an end-effector for a palletizing 3-DOF robotic arm, and movement of the gripper can be achieved by using a visual sensor to pinpoint the user's hand location in 3D space. With the aim of the stress analysis software, the exoskeleton and gripper designs were analyzed to evaluate the system strength against applied forces. Finally, based on the achieved results, the gripper and two-fingered exoskeleton prototypes were fabricated. Simulations and experimental results are reported, showing the potential of the HEXON in haptics and tele-operation applications, and the exoskeleton is used to operate a robotic arm and gripper while the user can perceive the objects virtually.

Realization of Swing Manipulation by 3-DOF Robot Arm for Unknown String via Parameter Estimation and Motion Generation

Dynamically manipulating flexible objects using robots is difficult. Some studies have been conducted that only considered one type of object with known properties or that needed an identification test for string properties in advance. We propose a method to realize the dynamic manipulation of a string with unknown characteristics. We use a mass-spring-damper model for the string and repeat three steps: motion generation, real manipulation, and parameter estimation. The proposed method estimates the string properties to realize the motion objective via the real manipulation of the string. An identification test in advance was not necessary. In this study, we focus on swing manipulation. This can increase the motion energy of a string without a high-power actuator. After making a large swing, the robot can throw strings to a more distant target, such as a hammer throw. This motion is useful for explanation robots, rescue robots, and so on. We modified the proposed method to generate a swing manipulation. Then, we investigate whether swing manipulation can be performed by the proposed method and demonstrate its effectiveness via experiments with various strings with unknown characteristics.

Six DOF Robotic Arm Prototype Modelling By Matlab

Abstract The study in this paper allows us to control the manipulator and achieve any desired position and orientation. The Forward Kinematics was done using Denavait Hartenberg (DH) parameters, also the forward kinematics equations and homogenous transformation matrix was validated using MATLAB Toolbox. The modeling was carried out using the Peter Corke robotics toolbox. Finally, the forward kinematic study and the robot arm’s movement equations were compared with practical measurements to make sure it fulfilled the desired purpose and that it could point to the desired coordinates with a precision of ±0.5 cm.

Design and Fabrication of 3-DOF Robot Arm Using Parallelogram Mechanisms

This paper focuses on the design, fabrication and control of a 3-DOF robot arm using stepper motors. The robot arm uses three parallelogram mechanisms to position the end-effector of the robot and keep the end-effector always parallel to the horizontal during the robot motion. The robot is designed on the Autodesk Inventor software. Separated parts of the robot are saved in the stereolithography (STL) file format. Then the parts are fabricated by a 3D printer. The movement of the robotic arm is driven by stepper motors and controlled by Arduino. The Arduino board implements kinematics calculation, creates pulses and sends them to three drivers to driven stepper motors. A software is developed to control the robot by sending the command to the Arduino board.

Optimal torso design selection for dual 7-DOF robot arm using von Mises stress and workspace analysis

Optimal torso design selection for dual 7-DOF robot arm using von Mises stress and workspace analysis

Path Planning with Adaptive Dimensionality

Path planning quickly becomes computationally hard as the dimensionality of the state-space increases. In this paper, we present a planning algorithm intended to speed up path planning for high-dimensional state-spaces such as robotic arms. The idea behind this work is that while planning in a high-dimensional state-space is often necessary to ensure the feasibilityof the resulting path, large portions of the path have a lower-dimensional structure. Based on this observation, our algorithm iteratively constructs a state-space of an adaptive dimensionality--a state-space that is high-dimensional only where the higher dimensionality is absolutely necessary for finding a feasible path. This often reduces drastically the size of the state-space, and as a result, the planning time and memory requirements. Analytically, we show that our method is complete and is guaranteed to find a solution if one exists, within a specified suboptimality bound. Experimentally, we apply the approach to 3D vehicle navigation (x, y, heading), and to a 7 DOF robotic arm on the Willow Garage’s PR2 robot. The results from our experiments suggest that ourmethod can be substantially faster than some of the state-of-the-art planning algorithms optimized for those tasks.

Modelling and Control of a 2-DOF Robot Arm with Elastic Joints for Safe Human-Robot Interaction.

Collaborative robots (or cobots) are robots that can safely work together or interact with humans in a common space. They gradually become noticeable nowadays. Compliant actuators are very relevant for the design of cobots. This type of actuation scheme mitigates the damage caused by unexpected collision. Therefore, elastic joints are considered to outperform rigid joints when operating in a dynamic environment. However, most of the available elastic robots are relatively costly or difficult to construct. To give researchers a solution that is inexpensive, easily customisable, and fast to fabricate, a newly-designed low-cost, and open-source design of an elastic joint is presented in this work. Based on the newly design elastic joint, a highly-compliant multi-purpose 2-DOF robot arm for safe human-robot interaction is also introduced. The mechanical design of the robot and a position control algorithm are presented. The mechanical prototype is 3D-printed. The control algorithm is a two loops control scheme. In particular, the inner control loop is designed as a model reference adaptive controller (MRAC) to deal with uncertainties in the system parameters, while the outer control loop utilises a fuzzy proportional-integral controller to reduce the effect of external disturbances on the load. The control algorithm is first validated in simulation. Then the effectiveness of the controller is also proven by experiments on the mechanical prototype.

Paquitop.arm, a Mobile Manipulator for Assessing Emerging Challenges in the COVID-19 Pandemic Scenario

The use of automation and robotics technologies for caregiving and assistance has become a very interesting research topic in the field of robotics. The spread of COVID-19 has highlighted the importance of social distancing in hospitals and health centers, and collaborative robotics can bring substantial improvements in terms of sparing health workers basic operations. Thus, researchers from Politecnico di Torino are working on Paquitop.arm, a mobile robot for assistive tasks. The purpose of this paper is to present a system composed of an omnidirectional mobile platform, a 6 DOF robot arm, and a depth camera. Task-oriented considerations are made to estimate a set of mounting parameters that represents a trade-off between the exploitation of the robot arm workspace and the compactness of the entire system. To this end, dexterity and force transmission indexes are introduced to study both the kinematic and the static behavior of the manipulator as a function of the mounting parameters. Finally, to avoid singularities during the execution of the task, the platform approach to the task workspaces is studied.

Learning latent actions to control assistive robots.

Assistive robot arms enable people with disabilities to conduct everyday tasks on their own. These arms are dexterous and high-dimensional; however, the interfaces people must use to control their robots are low-dimensional. Consider teleoperating a 7-DoF robot arm with a 2-DoF joystick. The robot is helping you eat dinner, and currently you want to cut a piece of tofu. Today’s robots assume a pre-defined mapping between joystick inputs and robot actions: in one mode the joystick controls the robot’s motion in the x–y plane, in another mode the joystick controls the robot’s z–yaw motion, and so on. But this mapping misses out on the task you are trying to perform! Ideally, one joystick axis should control how the robot stabs the tofu, and the other axis should control different cutting motions. Our insight is that we can achieve intuitive, user-friendly control of assistive robots by embedding the robot’s high-dimensional actions into low-dimensional and human-controllable latent actions. We divide this process into three parts. First, we explore models for learning latent actions from offline task demonstrations, and formalize the properties that latent actions should satisfy. Next, we combine learned latent actions with autonomous robot assistance to help the user reach and maintain their high-level goals. Finally, we learn a personalized alignment model between joystick inputs and latent actions. We evaluate our resulting approach in four user studies where non-disabled participants reach marshmallows, cook apple pie, cut tofu, and assemble dessert. We then test our approach with two disabled adults who leverage assistive devices on a daily basis.

Design of a 6-DOF robot manipulator for 3D printed construction

Robotics and their application in industrial automation are increasing over the decades. There are a variety of conventional and non-conventional applications of robotic manipulators. One example of the non-traditional application of robot manipulators is the 3D printing-based construction of houses and buildings. Up to date, different ambitious solutions and methods are proposed, and they are expanding fast. In large-scale production, 6 DOF robotic arms, designed by common manufacturers such as KUKA, DENSO are widely used in 3D construction. The main objective of this work is to model a 6 DOF robot manipulator for 3D printing-based construction technology. This paper presents two new designs of robot manipulators for construction purposes; one is to transport the building materials, and the other is to help print with the concrete mixtures. The simulation results are obtained applying fundamental theories of robotics through Roboanalyzer software. The simulation parameters are chosen for the designed specific model.

Articulated Robot Arm

In medical rehabilitation programs, trajectory tracking is used to increase the repeatability of joint movement and the patient's recovery in the early phases of rehabilitation. In order to achieve that, the robotic arm has been implemented since it can provide a precise and move in almost perfect motion. This manuscript aim to develop and simulate a 2DOF robotic arn that will able to tracking the trajectory successfully. Hence, in order to achieved that a modeling, simulation, and control of a Two Degree of Freedom (2-DOF) Robot Arm is being discussed in this manuscript. First, the robot specifications, as well as Robot Kinematics forward and inverse kinematics of a 2-DOF robot arm, are provided. The dynamics of the 2-DOF robot arm were then formulated in order to obtain motion equations by using the Eular-Lagrange Equation. For the controller of the robot, a control design was created utilising a PID controller. All the data is recorded from the margin of error as well as the overshoot and peak settling time is being record via matlab. The data is differentiate by with with controller, with PI and PID, in which the error is less than 12.5 and 1.63 consecutively. The data that being gathered show that a controller best suited in this rehabilitation robot

Vision-Guided Recognition Method for Working State of Robot Arm based on Machine Learning

To realize the capture of the target in any position within the working range of the robot arm, a vision-guided target recognition and positioning control method based on machine learning was proposed to improve the accuracy of the working state recognition. The system grabs four different contours of workpieces (triangle, pentagon, round, square and place in the designated area as the task, and by using the MATLAB to process the image information, and all the connected domains are marked bythe neighborhood areamarking algorithm. Later, the logarithmic coordinates-Fourier transform template matchingmethod is adopted to identify workpiece types and extract their centroid as the positioning reference coordinates.Combined with the 3-DOF robot arm, the standard D-H parametric method is usedto establishthe robot arm kinematics model, and through the inverse operation of the robot armand according to the position of the workpiece coordinates,the joint angle of each robot arm can be obtained. Later, it is sent to the lower microcontroller Arduino through a serial port, and then the control instruction is completed by the Arduino torealize the capture and placement of the workpiece and complete the work state recognition task.The experimental results show that the working state recognition system can meet the design requirements.

Design and Development of a 5 DOF Robotic Arm

Design and Development of a 5 DOF Robotic Arm

Beam orientation of EAST visible optical diagnostic using a robot-camera system

On Experimental Advanced Superconducting Tokamak (EAST) several visible optical diagnostics are utilized to measure the operation parameters of the plasma, in order to obtain the high performance and steady-state of the plasma profile. The light beam spatial orientation of these optical diagnostics needs to be calibrated before plasma experiment. The calibration process is carried out manually in past, which is quite tedious and exhausting especially in a narrow and harsh environment inside vacuum vessel. To improve this situation, an automatic calibration process based on a robot-camera system is proposed. A dedicated camera system is mounted at the end of a 6-DOF robot arm, to track and calculate the beam orientation and a via point. Both a simulation and a physical test platform were built to verify the performance of the proposed beam orientation process, and the results show a good accuracy of the beam orientation error within 0.5 degree.