Showing papers on "Kinematics published in 2013"
TL;DR: A software system, named human body model (HBM), to compute joint kinematics and kinetics for a full body model with 44 degrees of freedom, in real-time, and to estimate length changes and forces in 300 muscle elements is presented.
Abstract: Mechanical analysis of movement plays an important role in clinical management of neurological and orthopedic conditions. There has been increasing interest in performing movement analysis in real-time, to provide immediate feedback to both therapist and patient. However, such work to date has been limited to single-joint kinematics and kinetics. Here we present a software system, named human body model (HBM), to compute joint kinematics and kinetics for a full body model with 44 degrees of freedom, in real-time, and to estimate length changes and forces in 300 muscle elements. HBM was used to analyze lower extremity function during gait in 12 able-bodied subjects. Processing speed exceeded 120 samples per second on standard PC hardware. Joint angles and moments were consistent within the group, and consistent with other studies in the literature. Estimated muscle force patterns were consistent among subjects and agreed qualitatively with electromyography, to the extent that can be expected from a biomechanical model. The real-time analysis was integrated into the D-Flow system for development of custom real-time feedback applications and into the gait real-time analysis interactive lab system for gait analysis and gait retraining.
285 citations
TL;DR: The Xsens system most accurately determined the flexion/extension joint angle (CMC > 0.96) for all joints under all three walking conditions, and the joint angle measurements associated with the other two joint axes had lower correlation including complex CMC values.
Abstract: This study aims to validate a commercially available inertial sensor based motion capture system, Xsens MVN BIOMECH using its native protocols, against a camera-based motion capture system for the measurement of joint angular kinematics. Performance was evaluated by comparing waveform similarity using range of motion, mean error and a new formulation of the coefficient of multiple correlation (CMC). Three dimensional joint angles of the lower limbs were determined for ten healthy subjects while they performed three daily activities: level walking, stair ascent, and stair descent. Under all three walking conditions, the Xsens system most accurately determined the flexion/extension joint angle (CMC > 0.96) for all joints. The joint angle measurements associated with the other two joint axes had lower correlation including complex CMC values. The poor correlation in the other two joint axes is most likely due to differences in the anatomical frame definition of limb segments used by the Xsens and Optotrak systems. Implementation of a protocol to align these two systems is necessary when comparing joint angle waveforms measured by the Xsens and other motion capture systems.
246 citations
TL;DR: In this paper, a high smooth trajectory planning method is presented to improve the practical performance of tracking control for robot manipulators, which is designed as a combination of the planning with multi-degree splines in Cartesian space and multidirectional B-splines in joint space.
Abstract: In this paper a high smooth trajectory planning method is presented to improve the practical performance of tracking control for robot manipulators. The strategy is designed as a combination of the planning with multi-degree splines in Cartesian space and multi-degree B-splines in joint space. Following implementation, under the premise of precisely passing the via-points required, the cubic spline is used in Cartesian space planning to make either the velocities or the accelerations at the initial and ending moments controllable for the end effector. While the septuple B-spline is applied in joint space planning to make the velocities, accelerations and jerks bounded and continuous, with the initial and ending values of them configurable. In the meantime, minimum-time optimization problem is also discussed. Experimental results show that, the proposed approach is an effective solution to trajectory planning, with ensuring a both smooth and efficiency tracking performance with fluent movement for the robot manipulators.
217 citations
TL;DR: This study investigated the influence of subject-specific geometry and knee joint kinematics on the prediction of tibiofemoral contact forces using a calibrated EMG-driven neuromusculoskeletal model of the knee to improve the accuracy of medial contact forces and lateral contact forces by 47% and 7%, respectively.
216 citations
TL;DR: The potential of an instrumented mouthguard as a research tool for measuring in vivo impacts, which could help uncover the link between head impact kinematics and brain injury in American football, is demonstrated.
Abstract: The purpose of this study was to evaluate a novel instrumented mouthguard as a research device for measuring head impact kinematics. To evaluate kinematic accuracy, laboratory impact testing was performed at sites on the helmet and facemask for determining how closely instrumented mouthguard data matched data from an anthropomorphic test device. Laboratory testing results showed that peak linear acceleration (r2 = 0.96), peak angular acceleration (r2 = 0.89), and peak angular velocity (r2 = 0.98) measurements were highly correlated between the instrumented mouthguard and anthropomorphic test device. Normalized root-mean-square errors for impact time traces were 9.9 ± 4.4% for linear acceleration, 9.7 ± 7.0% for angular acceleration, and 10.4 ± 9.9% for angular velocity. This study demonstrates the potential of an instrumented mouthguard as a research tool for measuring in vivo impacts, which could help uncover the link between head impact kinematics and brain injury in American football.
188 citations
TL;DR: The clinical motivation, design considerations, kinematics, statics, and mechanical design of the IREP, a new insertable robotic end-effectors platform for single port access surgery, are presented.
Abstract: Single port access surgery (SPAS) presents surgeons with added challenges that require new surgical tools and surgical assistance systems with unique capabilities To address these challenges, we designed and constructed a new insertable robotic end-effectors platform (IREP) for SPAS The IREP can be inserted through a O15 mm trocar into the abdomen and it uses 21 actuated joints for controlling two dexterous arms and a stereo-vision module Each dexterous arm has a hybrid mechanical architecture comprised of a two-segment continuum robot, a parallelogram mechanism for improved dual-arm triangulation, and a distal wrist for improved dexterity during suturing The IREP is unique because of the combination of continuum arms with active and passive segments with rigid parallel kinematics mechanisms This paper presents the clinical motivation, design considerations, kinematics, statics, and mechanical design of the IREP The kinematics of coordination between the parallelogram mechanisms and the continuum arms is presented using the pseudo-rigid-body model of the beam representing the passive segment of each snake arm Kinematic and static simulations and preliminary experiment results are presented in support of our design choices
186 citations
TL;DR: It is concluded that adaptations in stride frequency, stride length and/or walking speed can result in an increase of the medio-lateral and backward margins of stability, while these adaptations do not seem to affect local dynamic stability.
Abstract: The purpose of the current study was to investigate whether adaptations of stride length, stride frequency, and walking speed, independently influence local dynamic stability and the size of the medio-lateral and backward margins of stability during walking. Nine healthy subjects walked 25 trials on a treadmill at different combinations of stride frequency, stride length, and consequently at different walking speeds. Visual feedback about the required and the actual combination of stride frequency and stride length was given during the trials. Generalized Estimating Equations were used to investigate the independent contribution of stride length, stride frequency, and walking speed on the measures of gait stability. Increasing stride frequency was found to enhance medio-lateral margins of stability. Backward margins of stability became larger as stride length decreased or walking speed increased. For local dynamic stability no significant effects of stride frequency, stride length or walking speed were found. We conclude that adaptations in stride frequency, stride length and/or walking speed can result in an increase of the medio-lateral and backward margins of stability, while these adaptations do not seem to affect local dynamic stability. Gait training focusing on the observed stepping strategies to enhance margins of stability might be a useful contribution to programs aimed at fall prevention.
185 citations
01 May 2013
TL;DR: Results indicate that the powered prosthesis provides gait kinematics that are considerably more representative of healthy gait, relative to the passive prosthesis, for both stair ascent and descent.
Abstract: This paper presents a finite state-based control system for a powered transfemoral prosthesis that provides stair ascent and descent capability. The control system was implemented on a powered prosthesis and evaluated by a unilateral, transfemoral amputee subject. The ability of the powered prosthesis to provide stair ascent and descent capability was assessed by comparing the gait kinematics, as recorded by a motion capture system, with the kinematics provided by a passive prosthesis, in addition to those recorded from a set of healthy subjects. The results indicate that the powered prosthesis provides gait kinematics that are considerably more representative of healthy gait, relative to the passive prosthesis, for both stair ascent and descent.
184 citations
24 Jun 2013
TL;DR: Preliminary analysis into how the walking kinematics differed across the subjects is reported - as a first step to understand the possible contribution to the velocity range and determine if the subjects who did not walk as well could be taught to improve by mimicking the better walkers.
Abstract: The ReWalkTM powered exoskeleton assists thoracic level motor complete spinal cord injury patients who are paralyzed to walk again with an independent, functional, upright, reciprocating gait. We completed an evaluation of twelve such individuals with promising results. All subjects met basic criteria to be able to use the ReWalkTM - including items such as sufficient bone mineral density, leg passive range of motion, strength, body size and weight limits. All subjects received approximately the same number of training sessions. However there was a wide distribution in walking ability. Walking velocities ranged from under 0.1m/s to approximately 0.5m/s. This variability was not completely explained by injury level The remaining sources of that variability are not clear at present. This paper reports our preliminary analysis into how the walking kinematics differed across the subjects - as a first step to understand the possible contribution to the velocity range and determine if the subjects who did not walk as well could be taught to improve by mimicking the better walkers.
175 citations
TL;DR: This paper proposes a distributed control scheme to solve the problem of decentralized cohesive motion control of a formation of autonomous vehicles or robots moving in three dimensions utilizing the notions of graph rigidity and persistence as well as techniques of virtual target tracking and smooth switching.
Abstract: In this paper, we consider the problem of decentralized cohesive motion control of a formation of autonomous vehicles or robots moving in three dimensions, where the formation is required to move from its initial setting (defined by the positions of the agents in the formation) to a final desired setting and, during this motion, maintain its formation geometry defined by the initial distances between the agent pairs We propose a distributed control scheme to solve this problem utilizing the notions of graph rigidity and persistence as well as techniques of virtual target tracking and smooth switching The distributed control scheme is developed by modeling the agent kinematics as single-velocity integrator; nevertheless, extension to the cases with practical kinematic and dynamic models of fixed-wing autonomous aerial vehicles and quadrotors is discussed In this context, we examine the maintenance of geometric formation of a swarm of autonomous flight vehicles The developed coordination and control schemes are verified via a number of simulations
172 citations
Book•
20 Feb 2013
TL;DR: In this paper, the authors present a model of a planar manipulator using loop closure and Jacobian analysis of the Stewart-Gough platform and the Jacobian matrix of a parallel manipulator.
Abstract: Introduction What Is a Robot? Robot Components Robot Degrees-of-Freedom Robot Classification The Aims and Scope of This Book Motion Representation Spatial Motion Representation Motion of a Rigid Body Homogeneous Transformations Problems Kinematics Introduction Loop Closure Method Kinematic Analysis of a Planar Manipulator Kinematic Analysis of Shoulder Manipulator Kinematic Analysis of Stewart-Gough Platform Problems Jacobians: Velocities and Static Forces Introduction Angular and Linear Velocities Jacobian Matrices of a Parallel Manipulator Velocity Loop Closure Singularity Analysis of Parallel Manipulators Jacobian Analysis of a Planar Manipulator Jacobian Analysis of Shoulder Manipulator Jacobian Analysis of the Stewart-Gough Platform Static Forces in Parallel Manipulators Stiffness Analysis of Parallel Manipulators Problems Dynamics Introduction Dynamics of Rigid Bodies: A Review Newton-Euler Formulation Virtual Work Formulation Lagrange Formulation Problems Motion Control Introduction Controller Topology Motion Control in Task Space Robust and Adaptive Control Motion Control in Joint Space Summary of Motion Control Techniques Redundancy Resolution Motion Control of a Planar Manipulator Motion Control of the Stewart-Gough Platform Problems Force Control Introduction Controller Topology Stiffness Control Direct Force Control Impedance Control Problems Appendix: Linear Algebra Vectors and Matrices Vector and Matrix Operations Eigenvalues and Singular Values Pseudo-Inverse Kronecker Product Appendix: Trajectory Planning Point-to-Point Motion Specified Path with Via Points Appendix: Nonlinear Control Review Dynamical Systems Stability Definitions Lyapunov Stability Krasovskii-Lasalle Theorem References Index
Patent•
08 Jan 2013TL;DR: In this article, a system for providing force information for a robotic surgical system is presented, which includes storing first kinematic position information and first actual position information for the first position of an end-effector, moving the end effector via the robotic operating system from the first to a second position, and providing force feedback regarding force applied at the second position.
Abstract: Methods of and a system for providing force information for a robotic surgical system. The method includes storing first kinematic position information and first actual position information for a first position of an end effector; moving the end effector via the robotic surgical system from the first position to a second position; storing second kinematic position information and second actual position information for the second position; and providing force information regarding force applied to the end effector at the second position utilizing the first actual position information, the second actual position information, the first kinematic position information, and the second kinematic position information. Visual force feedback is also provided via superimposing an estimated position of an end effector without force over an image of the actual position of the end effector. Similarly, tissue elasticity visual displays may be shown.
TL;DR: This work proposes a method to plan optimal whole-body dynamic motion in multi-contact non-gaited transitions using a B-spline time parameterization for the active joints and addresses the problem of the balance within the optimization problem.
Abstract: We propose a method to plan optimal whole-body dynamic motion in multi-contact non-gaited transitions. Using a B-spline time parameterization for the active joints, we turn the motion-planning problem into a semi-infinite programming formulation that is solved by nonlinear optimization techniques. Our main contribution lies in producing constraint-satisfaction guaranteed motions for any time grid. Indeed, we use Taylor series expansion to approximate the dynamic and kinematic models over fixed successive time intervals, and transform the problem (constraints and cost functions) into time polynomials which coefficients are function of the optimization variables. The evaluation of the constraints turns then into computation of extrema (over each time interval) that are given to the solver. We also account for collisions and self-collisions constraints that have not a closed-form expression over the time. We address the problem of the balance within the optimization problem and demonstrate that generating whole-body multi-contact dynamic motion for complex tasks is possible and can be tractable, although still time consuming. We discuss thoroughly the planning of a sitting motion with the HRP-2 humanoid robot and assess our method with several other complex scenarios.
TL;DR: In this article, a generalized kinematics model that allows automatic configurations of all five-axis machine tools using screw theory is presented. But the model is not suitable for CNC systems, as it requires the tool orientation vectors are represented by a fifth degree B-spline curve in a quaternion space.
Abstract: Typical five-axis machine tools have three translational and two rotary drives. This paper presents a generalized kinematics model that allows automatic configurations of all five-axis machine tools using screw theory. First, each kinematic element is modelled as a revolute joint, prismatic joint, workpiece or cutting tool. The kinematic elements are mathematically assembled through screw theory by using the base coordinate system. The general inverse kinematics solutions for both rotary and translational motions are evaluated. The singularities in five axis contouring are avoided by deforming splined tool orientation vectors. The tool orientation vectors are represented by a fifth degree B-spline curve in a quaternion space, while the movement of tool tip is represented by a fifth degree B-spline curve in the Cartesian space. Both splines, which form the C3 continuous tool path, are fitted to curve length parameter of the tool tip positions. If the tool path traverses the singular area of the machine, it is deformed by modifying the control points of the tool orientation spline in the quaternion space while respecting the machining tolerance. The proposed kinematics module, tool path generation algorithm and method for avoiding kinematic singularities are experimentally verified on a five-axis machine tool controlled by an in-house developed CNC system.
TL;DR: In this article, an experimental approach combining stereo-correlation and infrared thermography, that respectively provide the kinematic and thermal fields on the surface of the composites, are used in live recording during axis and off-axis tensile tests.
Abstract: The present work is devoted to damaging process in carbon–fiber reinforced laminated composites. An original experimental approach combining three optical measurement techniques is presented. Image stereo-correlation and infrared thermography, that respectively provide the kinematic and thermal fields on the surface of the composites, are used in live recording during axis and off-axis tensile tests. Special attention is paid to simultaneously conduct these two techniques while avoiding their respective influence. On the other hand, X-ray tomography allows a post-failure analysis of the degradation patterns within the laminates volume. All these techniques are non-destructive (without contact) and offer an interesting full-field investigation of the material response. Their combination allows a coupled analysis of different demonstrations of same degradation mechanisms. For instance, thermal events and densimetric fields show a random location of damage in the early stages of testing. The influence of the material initial anisotropy on damage growth, localization and failure mode can also be clearly put in evidence through various data. In addition to such characterization, this study illustrates at the same time the capabilities of the different full-field techniques and the damage features they can best capture respectively.
TL;DR: Data generated with the proposed methodology for predicting ground reaction forces (GRFs) during level walking without the help of a force plate may be used instead of raw GRF data in gait analysis and in calculating joint dynamic data using inverse dynamics.
01 Jan 2013
TL;DR: Motion Planning, Force Distribution, Application and Protoypes, Dynamics Modelling, and Kinematics and Interval Methods.
Abstract: Welcome.- Motion Planning.- Force Distribution.- Application and Protoypes.- Design and Components.- Kinematics and Interval Methods.- Calibration und Identification.- Control.- Dynamics Modelling.
22 Sep 2013
TL;DR: This paper proposes a framework for joint segmentation and recognition of surgical gestures from kinematic and video data using a combined Markov/semi-Markov conditional random field (MsM-CRF) model, and shows that the proposed model improves over a Markov or semi- Markov CRF when using video data alone, gives results that are comparable to state-of-the-art methods on kinematics data alone.
Abstract: Automatic surgical gesture segmentation and recognition can provide useful feedback for surgical training in robotic surgery. Most prior work in this field relies on the robot’s kinematic data. Although recent work [1,2] shows that the robot’s video data can be equally effective for surgical gesture recognition, the segmentation of the video into gestures is assumed to be known. In this paper, we propose a framework for joint segmentation and recognition of surgical gestures from kinematic and video data. Unlike prior work that relies on either frame-level kinematic cues, or segment-level kinematic or video cues, our approach exploits both cues by using a combined Markov/semi-Markov conditional random field (MsM-CRF) model. Our experiments show that the proposed model improves over a Markov or semi-Markov CRF when using video data alone, gives results that are comparable to state-of-the-art methods on kinematic data alone, and improves over state-of-the-art methods when combining kinematic and video data.
TL;DR: The study found that, there are rich research efforts in terms of KINEMATICS, DYNAMICS, MODELING and CONTROL methodologies for robotics hand design, and there are quite large number of attempts to acquire biologically inspired hands.
TL;DR: A new U-shaped space-time speed-accuracy function for performance outcome in tasks that have both spatial and temporal demands is revealed and it is shown that the contribution of either space or time to the performance score became increasingly asymmetrical at lower and higher average velocities.
TL;DR: It was hypothesized that a gradually reducing radius may attenuate sudden changes in anterior-posterior motion that occur in mid-flexion with traditional discrete-radius designs, and served as a useful pre-clinical design-phase tool to improve implant kinematics.
TL;DR: An image-guided control system is developed to robotically steer flexible needles with an asymmetric tip to reach the smallest lesions that can be detected using the state-of-the-art ultrasound imaging systems.
Abstract: Needle insertion procedures are commonly used for diagnostic and therapeutic purposes. In this paper, an image-guided control system is developed to robotically steer flexible needles with an asymmetric tip. Knowledge about needle deflection is required for accurate steering. Two different models to predict needle deflection are presented. The first is a kinematics-based model, and the second model predicts needle deflection that is based on the mechanics of needle–tissue interaction. Both models predict deflection of needles that undergo multiple bends. The maximum targeting errors of the kinematics-based and the mechanics-based models for 110-mm insertion distance using a $\phi$ 0.5-mm needle are 0.8 and 1.7 mm, respectively. The kinematics-based model is used in the proposed image-guided control system. The control system accounts for target motion during the insertion procedure by detecting the target position in each image frame. Five experimental cases are presented to validate the real-time control system using both camera and ultrasound images as feedback. The experimental results show that the targeting errors of camera and ultrasound image-guided steering toward a moving target are 0.35 and 0.42 mm, respectively. The targeting accuracy of the algorithm is sufficient to reach the smallest lesions ( $\phi$ 2 mm) that can be detected using the state-of-the-art ultrasound imaging systems.
TL;DR: Information is provided on the kinematic discrepancies between OMC and biplanar videoradiography that can be used to optimize methods employing both technologies for studying dynamic in vivo knee kinematics and kinetics during a jump-cut maneuver.
21 Jul 2013
TL;DR: A new method for acquiring physically realistic hand manipulation data from multiple video streams by introducing a composite motion control to simultaneously model hand articulation, object movement, and subtle interaction between the hand and object is described.
Abstract: This paper describes a new method for acquiring physically realistic hand manipulation data from multiple video streams. The key idea of our approach is to introduce a composite motion control to simultaneously model hand articulation, object movement, and subtle interaction between the hand and object. We formulate video-based hand manipulation capture in an optimization framework by maximizing the consistency between the simulated motion and the observed image data. We search an optimal motion control that drives the simulation to best match the observed image data. We demonstrate the effectiveness of our approach by capturing a wide range of high-fidelity dexterous manipulation data. We show the power of our recovered motion controllers by adapting the captured motion data to new objects with different properties. The system achieves superior performance against alternative methods such as marker-based motion capture and kinematic hand motion tracking.
TL;DR: A new continuum robot with three backbones is proposed, and a unified analytic method for the kinematics and dynamics of a multiple-backbone continuum robot is provided.
Abstract: Continuum robots have been the subject of extensive research due to their potential use in a wide range of applications. In this paper, we propose a new continuum robot with three backbones, and provide a unified analytic method for the kinematics and dynamics of a multiple-backbone continuum robot. The robot achieves actuation by independently pulling three backbones to carry out a bending motion of two-degrees- of-freedom (DoF). A three-dimensional CAD model of the robot is built and the kinematical equation is established on the basis of the Euler-Bernoulli beam. The dynamical model of the continuum robot is constructed by using the Lagrange method. The simulation and the experiment's validation results show the continuum robot can exactly bend into pre-set angles in the two-dimensional space (the maximum error is less than 5% of the robot length) and can make a circular motion in three-dimensional space. The results demonstrate that the proposed analytic method for the kinematics and dynamics of a continuum robot is feasible.
TL;DR: A model separation is proposed to simplify the control of the six-degrees-of-freedom (6DOF) nonlinear dynamics of the flying robot to deal with quad-rotor’s 3D-motion via two subsystems: dynamic and kinematic underactuaded subsystems.
Abstract: The paper addresses the flight control of a quad-rotor subject to two dimensional unknown static/varying wind disturbances. A model separation is proposed to simplify the control of the six-degrees-of-freedom (6DOF) nonlinear dynamics of the flying robot. Such approach allows to deal with quad-rotor's 3D-motion via two subsystems: dynamic (altitude and MAV-relative forward velocity) and kinematic (nonholonomic-like navigation) subsystems. In terms of control, a hierarchical control is used as the overall control structure to stabilize the kinematic underactuaded subsystem. A control strategy based on sliding-mode and adaptive control techniques is proposed to deal with slow and fast time-varying wind conditions, respectively. This choice not only provides well tracking control but also improves the estimation of unknown disturbance. The backstepping technique is used to stabilize the inner-loop heading dynamics, such recursive design takes into account a constrained heading rate. Promising simulations results show the validity of the proposed control strategy while tracking a time-parameterized straight-line and sinusoidal trajectory.
TL;DR: The optimal design, fabrication, and control of a novel compliant flexure-based totally decoupled XY micropositioning stage driven by electromagnetic actuators that can bear a heavy load because of its optimal mechanical structure is presented.
Abstract: This paper presents the optimal design, fabrication, and control of a novel compliant flexure-based totally decoupled XY micropositioning stage driven by electromagnetic actuators. The stage is constructed with a simple structure by employing double four-bar parallelogram flexures and four noncontact types of electromagnetic actuators to realize the kinematic decoupling and force decoupling, respectively. The kinematics and dynamics modeling of the stage are conducted by resorting to compliance and stiffness analysis based on matrix method, and the parameters are obtained by multiobjective genetic algorithm (GA) optimization method. The analytical models for electromagnetic forces are also established, and both mechanical structure and electromagnetic models are validated by finite-element analysis via ANSYS software. It is found that the system is with hysteresis and nonlinear characteristics when a preliminary open-loop test is conducted; thereafter, a simple PID controller is applied. Therefore, an inverse Preisach model-based feedforward sliding-mode controller is exploited to control the micromanipulator system. Experiments show that the moving range can achieve 1 mm t 1 mm and the resolution can reach ±0.4 μm. Moreover, the designed micromanipulator can bear a heavy load because of its optimal mechanical structure.
TL;DR: The proposed system is the first validated markerless measurement system using the Microsoft Kinect that is capable of measuring finger joint kinematics and is suitable for home-based motion capture for the hand and achieves this objective.
Abstract: Dynamic movements of the hand, fingers, and thumb are difficult to measure due to the versatility and complexity of movement inherent in function. An innovative approach to measuring hand kinematics is proposed and validated. The proposed system utilizes the Microsoft Kinect and goes beyond gesture recognition to develop a validated measurement technique of finger kinematics. The proposed system adopted landmark definition (validated through ground truth estimation against assessors) and grip classification algorithms, including kinematic definitions (validated against a laboratory-based motion capture system). The results of the validation show 78% accuracy when identifying specific markerless landmarks. In addition, comparative data with a previously validated kinematic measurement technique show accuracy of MCP ± 10° (average absolute error (AAE) = 2.4°), PIP ± 12° (AAE = 4.8°), and DIP ± 11° (AAE = 4.8°). These results are notably better than clinically based alternative manual measurement techniques. The ability to measure hand movements, and therefore functional dexterity, without interfering with underlying composite movements, is the paramount objective to any bespoke measurement system. The proposed system is the first validated markerless measurement system using the Microsoft Kinect that is capable of measuring finger joint kinematics. It is suitable for home-based motion capture for the hand and, therefore, achieves this objective.
TL;DR: A robotic, multi-articulated bat wing that allows us to measure power input and force output simultaneously, across a range of kinematic parameters, and lessons about the structure of living bats learned from trying to mimic their flight in a robotic wing are described.
Abstract: There are many challenges to measuring power input and force output from a flapping vertebrate. Animals can vary a multitude of kinematic parameters simultaneously, and methods for measuring power and force are either not possible in a flying vertebrate or are very time and equipment intensive. To circumvent these challenges, we constructed a robotic, multi-articulated bat wing that allows us to measure power input and force output simultaneously, across a range of kinematic parameters. The robot is modeled after the lesser dog-faced fruit bat, Cynopterus brachyotis, and contains seven joints powered by three servo motors. Collectively, this joint and motor arrangement allows the robot to vary wingbeat frequency, wingbeat amplitude, stroke plane, downstroke ratio, and wing folding. We describe the design, construction, programing, instrumentation, characterization, and analysis of the robot. We show that the kinematics, inputs, and outputs demonstrate good repeatability both within and among trials. Finally, we describe lessons about the structure of living bats learned from trying to mimic their flight in a robotic wing.
TL;DR: An efficient analytic algorithm based on dialytic elimination is presented and an approach for stability analysis is developed, and the stability of all equilibrium configurations is analyzed.
Abstract: This paper addresses the kinematics of cooperative transport of payloads suspended by multiple aerial robots with cables. In such problems, it is important to determine the positions of the aerial robots to achieve a specified position and orientation of the payload. In general, this inverse kinematics problem has no solutions for the case with one or two robots and infinitely many solutions for three or more robots. However, in the case with three robots, when the tensions of the cables are also specified, this inverse kinematics problem is shown to have a finite number of solutions. In order to obtain all possible solutions, an efficient analytic algorithm based on dialytic elimination is presented in this paper. Case studies with an equilateral triangle payload and a general payload are used for demonstration. In addition, a numerical procedure is developed to determine the set of allowable tensions. Finally, an approach for stability analysis is developed, and the stability of all equilibrium configurations is analyzed.