On-Screen Visual Feedback Effect on Static Balance Assessment with Perturbations.

In this study, the novel mobile dynamometric platform, OREKA, was utilized to perform an extensive analysis of the centre of pressure behaviour during different tilt motion exercises. This platform is based on a parallel manipulator mechanism and can perform rotations around both horizontal axes and a vertical translation. A group of participants took part in an experimental campaign involving the completion of a set of exercises. The aim was to evaluate the platform's potential practical application and investigate the impact of visual on-screen feedback on centre of pressure motion through multiple balance indicators. The use of the OREKA platform enables the study of the impact on a user's balance control behaviour under different rotational perturbations, depending on the availability of real-time visual feedback on a screen. Furthermore, it presented data identifying postural control variations among clinically healthy individuals. These findings are fundamental to comprehending the dynamics of body balance. Further investigation is needed to explore these initial findings and fully unlock the potential of the OREKA platform for balance assessment methodologies.

Collision Detection of a HEXA Parallel Robot Based on Dynamic Model and a Multi-Dual Depth Camera System.

This paper introduces a Hexa parallel robot and obstacle collision detection method based on dynamic modeling and a computer vision system. The processes to deal with the collision issues refer to collision detection, collision isolation, and collision identification applied to the Hexa robot, respectively, in this paper. Initially, the configuration, kinematic and dynamic characteristics during movement trajectories of the Hexa parallel robot are analyzed to perform the knowledge extraction for the method. Next, a virtual force sensor is presented to estimate the collision detection signal created as a combination of the solution to the inverse dynamics and a low-pass filter. Then, a vision system consisting of dual-depth cameras is designed for obstacle isolation and determining the contact point location at the end-effector, an arm, and a rod of the Hexa robot. Finally, a recursive Newton-Euler algorithm is applied to compute contact forces caused by collision cases with the real-Hexa robot. Based on the experimental results, the force identification is compared to sensor forces for the performance evaluation of the proposed collision detection method.

Design and Experimental Characterization of L-CADEL v2, an Assistive Device for Elbow Motion.

An experimental characterization is presented for an improved version of a wearable assistive device for elbow motion. The design is revised with respect to requirements for elbow motion assistance, looking at applications both in rehabilitation therapies and exercising of elderly people. A laboratory prototype is built with lightweight, portable, easy-to-use features that are verified with test results, whose discussion is also provided as a characterization of operating performance.

Development and Control of a Pneumatic-Actuator 3-DOF Translational Parallel Manipulator with Robot Vision.

A vision-based three degree-of-freedom translational parallel manipulator (TPM) was developed. The developed TPM has the following characteristics. First, the TPM is driven by three rodless pneumatic actuators and is designed as a horizontal structure to enlarge its horizontal working space to cover a conveyor. Then, a robot-vision system (including a webcam mounted on the TPM) collects images of objects on the conveyor and transfers them through the LabVIEW application programming interface for image processing. Since it is very difficult to achieve precise position control of the TPM due to the nonlinear couplings among the robot axes, feedback linearization is utilized to design an adaptive interval type-2 fuzzy controller with self-tuning fuzzy sliding-mode compensation (AIT2FC-STFSMC) for each rodless pneumatic actuator to attenuate nonlinearities, function approximation errors, and external disturbances. Finally, experiments proved that the vision-based three degree-of-freedom TPM was capable of accurately tracking desired trajectories and precisely executing pick-and-place movement in real time.

Cable-Driven Parallel Robot with Reconfigurable End Effector Controlled with a Compliant Actuator.

Redundancy in cable-driven parallel robots provides additional degrees of freedom that can be used to achieve different objectives. In this robot, this degree of freedom is used to act on a reconfigurable end effector with one degree of freedom. A compliant actuator actuated by one motor exerts force on both bodies of the platform. Due to the high tension that appears in this cable in comparison with the rest of the cables, an elastic model was developed for solving the kinestostatic and wrench analysis. A linear sensor was used in one branch of this cable mechanism to provide the needed intermediate values. The position of one link of the platform was fixed in order to focus this analysis on the relationship between the cables and the platform's internal movement. Position values of the reconfigurable end effector were calculated and measured as well as the tension at different regions of the compliant actuator. The theoretical values were compared with dynamic simulations and real prototype results.

Modeling and Analysis of a 2-DOF Spherical Parallel Manipulator.

The kinematics of a two rotational degrees-of-freedom (DOF) spherical parallel manipulator (SPM) is developed based on the coordinate transformation approach and the cosine rule of a trihedral angle. The angular displacement, angular velocity, and angular acceleration between the actuators and end-effector are thus determined. Moreover, the dynamic model of the 2-DOF SPM is established by using the virtual work principle and the first-order influence coefficient matrix of the manipulator. Eventually, a typical motion plan and simulations are carried out, and the actuating torque needed for these motions are worked out by employing the derived inverse dynamic equations. In addition, an analysis of the mechanical characteristics of the parallel manipulator is made. This study lays a solid base for the control of the 2-DOF SPM, and also provides the possibility of using this kind of spherical manipulator as a 2-DOF orientation, angular velocity, or even torque sensor.

The Integration of the Image Sensor with a 3-DOF Pneumatic Parallel Manipulator.

The study aims to integrate the image sensor for a three-axial pneumatic parallel manipulator which can pick and place objects automatically by the feature information of the image processed through the SURF algorithm. The SURF algorithm is adopted for defining and matching the features of a target object and an object database. In order to accurately mark the center of target and strengthen the feature matching results, the random sample and consensus method (RANSAC) is utilized. The ASUS Xtion Pro Live depth camera which can directly estimate the 3-D location of the target point is used in this study. A set of coordinate estimation calibrations is developed for enhancing the accuracy of target location estimation. This study also presents hand gesture recognition exploiting skin detection and noise elimination to determine the active finger count for input signals of the parallel manipulator. The end-effector of the parallel manipulator can be manipulated to the desired poses according to the measured finger count. Finally, the proposed methods are successfully to achieve the feature recognition and pick and place of the target object.

Design and operation of a Peucedani Radix weeding device based on YOLOV5 and a parallel manipulator.

To avoid excessive use of herbicides in the weeding operations of Peucedani Radix, a common Chinese herb, a precision seedling avoidance and weeding agricultural robot was designed for the targeted spraying of herbicides. The robot uses YOLOV5 combined with ExG feature segmentation to detect Peucedani Radix and weeds and obtain their corresponding morphological centers. Optimal seedling avoidance and precise herbicide spraying trajectories are generated using a PSO-Bezier algorithm based on the morphological characteristics of Peucedani Radix. Seedling avoidance trajectories and spraying operations are executed using a parallel manipulator with spraying devices. The validation experiments showed that the precision and recall of Peucedani Radix detection were 98.7% and 88.2%, respectively, and the weed segmentation rate could reach 95% when the minimum connected domain was 50. In the actual Peucedani Radix field spraying operation, the success rate of field precision seedling avoidance herbicide spraying was 80.5%, the collision rate between the end actuator of the parallel manipulator and Peucedani Radix was 4%, and the average running time of the parallel manipulator for precision herbicide spraying on a single weed was 2 s. This study can enrich the theoretical basis of targeted weed control and provide reference for similar studies.

Study on modeling and dynamic performance of a planar flexible parallel manipulator based on finite element method.

The application of a high-speed parallel manipulator necessitates the adoption of a lightweight design to reduce dead weight. However, this increases the elastic deformation of certain components, affecting the dynamic performance of the system. This study examined a 2-DOF planar flexible parallel manipulator. A dynamic model of the parallel manipulator composed of fully flexible links was established using a floating reference coordinate system and a combination of the finite element and augmented Lagrange multiplier methods. A dynamic analysis of the simplified model under three driving torque modes showed that the axial deformation was less than the transverse deformation by three orders of magnitude. Further, the kinematic and dynamic performance of the redundant drive was significantly better than that of the non-redundant drive, and the vibration was well suppressed in the redundant drive mode. In addition, the comprehensive performance of driving Mode 2 was better than that of the other two modes. Finally, the validity of the dynamic model was verified by modeling via Adams. The modular modeling method is conducive to the extension to other models and programming. Furthermore, the dynamic model of the established fully flexible link system can aid in optimizing the lightweight design and dynamic performance of the parallel manipulator.

Wearable neck assistive device strain evaluation study on surface neck muscles for head/neck movements.

BACKGROUND: This article examines a dynamic wearable assistive device for individuals suffering from pain in the neck. As a part of the clinical treatment, static braces/cervical collars are suggested, however, these collars aid the person in maintaining the upright position of the head but restrict the head motion to a single configuration. To address this problem, a dynamic wearable assistive cervical collar is fabricated based on human anatomical head/neck data. OBJECTIVE: The objective of this study is to observe the strain acting on the neck surface muscles for bending and compression neck movements with and without the neck brace using a strain sensor. METHODS: To evaluate the performance of this device, experimental trials were conducted on test subjects to find out the angular tilt of the head with the device worn using the cervical range of motion (CROM) device. In addition, a neck surface muscle strain study is also conducted using strain sensors to investigate the strain produced while using the wearable assistive device. The strain on the neck surface muscle is measured using NI-9236 strain DAQ (data acquisition system). In this experimental study, a group of aged individuals with minor neck pain were recruited to study the head/neck movements. RESULTS: It was found that by using the proposed assistive device, test subjects were able to mimic 65% of human head/neck movements like flexion, extension, lateral bending, and rotation, and the strain generated from the neck surface muscle was minimal. CONCLUSION: The results show that using the designed assistive device reduced the strain on neck surface muscle, and strain obtained is within the range of 40 × 10-6 to 80 × 10-6, and may aid in recovery of the individuals suffering with neck pain.

Design and kinematic analysis of a novel rehabilitative robotic walking simulation device.

This paper presents an original rehabilitative robotic walking simulation device. As a novel feature, it can duplicate the walking motion of the feet completely by including the motion of the metatarsophalangeal joints as well. It is also adjustable to different foot sizes and gait parameters such as speed, step length, and foot elevation. The presented device comprises two identical mechanisms that simulate the right and left feet. Each mechanism is designed as a planar parallel manipulator with three degrees of freedom and thus its platform (i.e. foot plate) can duplicate the sagittal-plane motion of a foot completely. A prototype of the device is already built, patented, and tested by several people, two of whom are physiotherapists. In the paper, the inverse and forward kinematic analyses of each parallel manipulator are also presented. The inverse kinematic analysis is carried out based on a typical gait cycle data of a healthy person gathered from the related literature. The results of the inverse kinematic analysis are then used as reference trajectory data in testing the device with different healthy people at different speeds.

Structural design of a positioning spherical parallel manipulator to be utilized in brain biopsy.

BACKGROUND: During the last decades, there has been a great increase in the usage of robotic systems during surgeries in order to reach increased operational precision, reduced operation times, enhanced recovery periods, low infection risks, and limited scar formations for aesthetic reasons. In light of this, the current study focuses on the field of robotic surgery by introducing the kinematic structure of the precise robotic positioning manipulator for brain biopsy. METHODOLOGY: Throughout the study, two degrees of freedom spherical parallel robot manipulator was proposed in order to position brain biopsy needle precisely during the brain biopsy operation on the target workspace. RESULTS: Direct and inverse kinematics of the manipulator were carried out parametrically by using quaternion algebra. The prototype of the manipulator was manufactured by rapid prototyping for hardware verification. CONCLUSIONS: Hardware verification of the manufactured prototype was completed distinctly by using motion capture cameras and manufactured mock-up setup that mimics tumour locations inside the brain. Successful verification results in terms of precision were achieved.

Development of a new 3-DOF parallel manipulator for minimally invasive surgery.

This article proposes a novel dexterous endoscopic parallel manipulator for minimally invasive surgery. The proposed manipulator has 3 degrees of freedom (3-DOF), which consist of two rotational DOFs and one translational DOF (2R1T DOFs). The manipulator consists of 3 limbs exhibiting identical kinematic structure. Each limb contains an active prismatic joint followed by 2 consecutive passive universal joints. The proposed manipulator has a unique arrangement of its joints' axes. This unique arrangement permits large bending angles, ±90° in any direction, and a workspace almost free from interior singularities. These advantages allow the proposed manipulator to outperforms existing surgical manipulators. However, this unique arrangement makes the analysis of the robot extremely difficult. Therefore, a geometrical/analytical approach is used to facilitate its singularity analysis. Construction of the virtual prototype is accomplished using ADAMS software to validate the proposed manipulator and its bending capability. A closed-form solution for inverse kinematics is obtained analytically. Also, the forward kinematics solution is obtained numerically. Moreover, evaluation of the workspace is achieved using motion/force transmissibility indices. A practical experiment has been performed using a scaling technique and PID controller. The experimental results show the feasibility of the teleoperated surgical system using the proposed parallel manipulator as the slave.

Autonomous neuro-registration for robot-based neurosurgery.

PURPOSE: Neuro-registration is of primary importance as it has a bearing on the accuracy of neurosurgery. Although the accuracy of surgical robots is within the acceptable medical standards, the overall surgical accuracy is dictated by the errors in the neuro-registration process. The purpose of this work is to automate the neuro-registration process to improve the overall accuracy of the robot-based neurosurgery. METHOD: A highly accurate 6-degree-of-freedom Parallel Kinematic Mechanism (6D-PKM) robot is used for both neuro-registration and neurosurgery. In neuro-registration, after measurement of points in the medical image space, the end-platform of the 6D-PKM surgical robot carrying the camera will autonomously navigate towards the fiducial markers to measure its coordinates in the real patient space. An accurate relationship between the medical image space and the real patient space is established, and the same robot will navigate the surgical tool to the target. RESULTS: In order to validate the proposed method for autonomous neuro-registration, experiments are performed using four phantoms. The four phantoms are as follows: PVC skull model, two acrylic blocks and a glass jar with coaxial shells. These phantoms are specifically designed to simulate the neurosurgical process. All the phantoms are registered successfully using the above-stated method. After autonomous neuro-registration, the coordinates of the target point are determined. Neurosurgery validation is carried out by attaching a 1-mm-diameter needle to the robot platform, which is autonomously traversed to reach the target point passing through the two 2-mm-diameter coaxial holes. The experiments are repeated, and the results reveal very good repeatability. CONCLUSION: A method for autonomous neuro-registration has been developed. The robot has been successfully registered using the above method. After successful neuro-registration the overall accuracy of the robot-based neurosurgery is considerably improved. The other benefits of the above method are as follows: elimination of line-of-sight problem, no need of extra unit for neuro-registration, less time for registration, intraoperative registration, human error reduction and low cost.

Design and performance analysis of a 3-RRR spherical parallel manipulator for hip exoskeleton applications.

This paper presents the design and performance analysis and experimental study of a 3-RRR spherical parallel manipulator in the context of hip exoskeleton applications. First, the mechanism's inverse kinematics analysis and Jacobian matrix development are revisited. Manipulability, dexterity, and rotational sensitivity indices are then evaluated for two different methods of attachment to the human body. The superior attachment method in terms of these performance measures is indicated, and an experimental study based on the selected method is conducted; the experiment involves testing the capability of a 3-RRR manipulator's end-effector in tracking the motions experienced by a human hip joint during normal gait cycles. Finally, the results of the experimental study indicate that the manipulator represents a feasible hip exoskeleton solution providing total kinematic compliance with the human hip joint's 3-degree-of-freedom motion capabilities.

In-bore prostate transperineal interventions with an MRI-guided parallel manipulator: system development and preliminary evaluation.

BACKGROUND: Robot-assisted minimally-invasive surgery is well recognized as a feasible solution for diagnosis and treatment of prostate cancer in humans. METHODS: This paper discusses the kinematics of a parallel 4 Degrees-of-Freedom (DOF) surgical manipulator designed for minimally invasive in-bore prostate percutaneous interventions through the patient's perineum. The proposed manipulator takes advantage of four sliders actuated by MRI-compatible piezoelectric motors and incremental rotary encoders. Errors, mostly originating from the design and manufacturing process, need to be identified and reduced before the robot is deployed in clinical trials. RESULTS: The manipulator has undergone several experiments to evaluate the repeatability and accuracy (about 1 mm in air (in x or y direction) at the needle's reference point) of needle placement, which is an essential concern in percutaneous prostate interventions. CONCLUSION: The acquired results endorse the sustainability, precision and reliability of the manipulator. Copyright © 2015 John Wiley & Sons, Ltd.

Robust nonlinear PID-like fuzzy logic control of a planar parallel (2PRP-PPR) manipulator.

In this paper, a robust nonlinear proportional-integral-derivative (PID)-like fuzzy control scheme is presented and applied to complex trajectory tracking control of a 2PRP-PPR (P-prismatic, R-revolute) planar parallel manipulator (motion platform) with three degrees-of-freedom (DOF) in the presence of parameter uncertainties and external disturbances. The proposed control law consists of mainly two parts: first part uses a feed forward term to enhance the control activity and estimated perturbed term to compensate for the unknown effects namely external disturbances and unmodeled dynamics, and the second part uses a PID-like fuzzy logic control as a feedback portion to enhance the overall closed-loop stability of the system. Experimental results are presented to show the effectiveness of the proposed control scheme.

Mechanical chest compression with a medical parallel manipulator for cardiopulmonary resuscitation.

BACKGROUND: Chest compression is the primary technique in emergency situations for resuscitating patients who have a cardiac arrest. Even for experienced personnel, it is difficult to perform chest compressions at the correct compression rate and depth. METHODS: We describe a new translational three-revolute-revolute-revolute (3-RRR) parallel manipulator designed for delivering chest compressions. The kinematic and chest analyses have been carried out analytically. The motion of the parallel manipulator while performing chest compressions was simulated under experimental conditions and the results were verified in MSC ADAMS software. RESULTS: Simulation and experimental results had more or less similar results. The proposed parallel manipulator was able to achieve 120 compressions/min (cpm) with a depth in the range 38-51 mm during cardio-pulmonary resuscitation (CPR). CONCLUSIONS: The design of the manipulator makes it easy to deploy for performing chest compressions at the correct compression rate and depth, as outlined in the 2010 resuscitation guidelines.

Femoral fracture reduction with a parallel manipulator robot on a traction table.

BACKGROUND: A parallel manipulator robot (PMR) on a traction table was developed to achieve better alignment of a fractured femur and reduce radiation exposure to both patients and physicians. METHODS: A PMR was built with a disk platform and a two-thirds circular ring. Fracture reductions were performed on eight artificially broken sawbone models and a cadaveric model. Fracture reduction was achieved using six degrees of freedom (6-DOF) movements of the two-thirds circular ring, while the PMR disk platform and the proximal femur remained stationary. RESULTS: Axial discrepancy, lateral translation and angulation had mean errors of 1.31 ± 0.45, 2.43 ± 0.49 and 2.26 ± 0.23 mm, respectively, when coarse adjustment was used. For the fine adjustment step, the mean errors were 0.63 ± 0.19 mm for axial discrepancy and 0.75 ± 0.26 mm for lateral translation. CONCLUSION: Femoral shaft fracture reduction with PMR on a traction table is a feasible and accurate approach to fracture reduction.