Kinematic Redundancy Research Articles

Task-Space Motion Planning of MRI-Actuated Catheters for Catheter Ablation of Atrial Fibrillation.

This paper presents a motion planning algorithm for Magnetic Resonance Imaging (MRI) actuated catheters for catheter ablation of atrial fibrillation. The MRI-actuated catheters is a new robotic catheter concept which utilizes MRI for remote steering and guidance. Magnetic moments generated by a set of coils wound near the tip are used to steer the catheter under MRI scanner magnetic field. The catheter during an ablation procedure is modeled as a constrained robotic manipulator with flexible joints, and the proposed motion-planning algorithm calculates a sequence of magnetic moments based on the manipulator model to move the tip of the catheter along a predefined trajectory on the surface of the left atrium. The difficulties in motion planning of the catheter are due to kinematic redundancy and underactuation. The proposed motion planning algorithm overcomes the challenges by operating in the task space instead of the configuration space. The catheter is then regulated around this nominal trajectory using feedback control to reduce the effect of uncertainties.

Biologically inspired deoxyribonucleic acid soft computing for inverse kinematics solver of five-DOF robotic manipulators

This paper presents a biologically inspired deoxyribonucleic acid (DNA) algorithm for solving the inverse kinematics of five degree-of-freedom (DOF) robotic manipulators. Although the 5-DOF robotic manipulator agilely maneuvers from one pose to another and easily performs some tasks, the inverse kinematics problem of the system is redundant. This problem has no general closed-form solutions or analytical solutions for the 5-DOF manipulator. The DNA soft computing is proposed to solve the redundant inverse kinematics problem of the 5-DOF robotic manipulators more efficiently. Simulation results are conducted to illustrate the effectiveness and merit of the proposed methods in comparison with conventional genetic algorithm (GA) and particle swarm optimization.

Task-relevance of grasping-related degrees of freedom in reach-to-grasp movements.

The kinematic redundancy of the human arm enables the rotation of the arm plane about the shoulder-wrist axis, represented by a swivel angle, which is affected by hand orientation when grasping. The coordination of grasping-related degrees of freedom (GR-DOFs), including swivel angle, forearm supination, wrist flexion and radial deviation, depends on their task-relevance, which can be quantified by the ratio of a joint's active motion range to its total motion range (R-AMR). The R-AMR values are computed across the target position and orientation to compare the task-relevance of the GR-DOFs. Statistical analysis of R-AMR values at the end of reach-to-grasp movements shows that among the GR-DOFs, radial deviation is most sensitive to changes in target position, while forearm supination is most sensitive to changes in target orientation. The forearm supination and swivel angle coordinate for energy-efficiency such that the swivel angle, which adjusts the posture of the whole arm, is largely unused until the forearm supination approaches its joint limit. The results further the understanding of the human motor control system in arm motion control and may benefit the design of the control algorithm for the upper limb exoskeleton.

Generating human-like movements for robotic arms

In this paper, the generation of trajectories of both end-effector and joints for human-like reaching and grasping motions is studied. In reaching movement, the human-like end-effector trajectory is obtained based on the minimum jerk model. A total potential energy criterion is constructed to resolve the kinematic redundancy of human arm in the target position. Gradient Projection Method (GPM) is adopted to trace the human-like end-effector trajectory while minimizing the total potential energy to generate the human-like joint trajectory. In grasping movement, the total potential energy and wrist discomfort are synthesized to resolve the kinematic redundancy of human arm in the target position and orientation. A new planner, Gradient Projection Method based Rapidly-exploring Random Tree (GPM-RRT) algorithm, is proposed to generate the human-like end-effector trajectory by goal biasing and the human-like joint trajectory by minimizing the synthesis of the total potential energy and wrist discomfort. The criteria and algorithm are verified by simulations and experiments.

The cost of moving optimally: kinematic path selection.

It is currently unclear whether the brain plans movement kinematics explicitly or whether movement paths arise implicitly through optimization of a cost function that takes into account control and/or dynamic variables. Several cost functions are proposed in the literature that are very different in nature (e.g., control effort, torque change, and jerk), yet each can predict common movement characteristics. We set out to disentangle predictions of the different variables using a combination of modeling and empirical studies. Subjects performed goal-directed arm movements in a force field (FF) in combination with visual perturbations of seen hand position. This FF was designed to have distinct optimal movements for muscle-input and dynamic costs while leaving kinematic cost unchanged. Visual perturbations in turn changed the kinematic cost but left the dynamic and muscle-input costs unchanged. An optimally controlled, physiologically realistic arm model was used to predict movements under the various cost variables. Experimental results were not consistent with a cost function containing any of the control and dynamic costs investigated. Movement patterns of all experimental conditions were adequately predicted by a kinematic cost function comprising both visually and somatosensory perceived jerk. The present study provides clear behavioral evidence that the brain solves kinematic and mechanical redundancy in separate steps: in a first step, movement kinematics are planned; and in a second, separate step, muscle activation patterns are generated.

Optimization of kinematic redundancy and workspace analysis of a dual-arm cam-lock robot

SUMMARYIn this paper, the problem of obtaining the optimal trajectory of a Dual-Arm Cam-Lock (DACL) robot is addressed. The DACL robot is a reconfigurable manipulator consisting of two cooperative arms, which may act separately. These may also be cam-locked in each other in some links and thus lose some degrees of freedom while gaining higher structural stiffness. This will also decrease their workspace volume. It is aimed to obtain the optimal configuration of the robot and the optimal joint trajectories to minimize the consumed energy for following a specific task space path. The Pontryagin's Minimum Principle is utilized with a shooting method to resolve kinematic redundancy. Numerical examples are investigated to show optimal trajectories in different cam-locked configurations, and the final decision is made based on a selection table of the computed performance indices.

Comparing Approaches for Actuator Redundancy Resolution in Biarticularly-Actuated Robot Arms

Biarticular actuators-actuators spanning two joints-play a fundamental role in robot arm designs based on the human musculoskeletal actuation structure. Unlike kinematic redundancy, actuator redundancy resulting from biarticular actuation brings advantages such as increased stability, reduced link inertia, and decreased nonlinearity of the end-effector force with respect to the force direction. The way the actuator redundancy is resolved is a fundamental problem, as it strongly characterizes robot arms performance. In this study, the six most significant actuation redundancy resolution approaches in the literature-1-norm, 2-norm, infinity-norm, phase different control (PDC), nonlinear hase different control (NLPDC), and linear programming (LP)-are analyzed with respect to their design, and experimentally compared with each other using BiWi, a biarticularly actuated and wire-driven robot arm. In addition, an integrated control framework to resolve actuator redundancy maximizing end-effector force and simultaneously minimizing the necessary input torques is proposed.

Development and experimental study of a redundant hybrid machine with five-face milling capability in one setup

A hybrid milling machine with actuation redundancy is developed in the current paper. This machine is capable of five-face milling in one setup. A redundant parallel kinematic module (PKM) is proposed by the introduction of actuation redundancy. Based on this module, the hybrid mechanism of the machine is presented. A local minimized transmission index is proposed to evaluate the motion/force transmissibility of the redundant PKM. The finite element analysis (FEA) simulation is used in the mechanical design of the machine to verify the stiffness and frequency characteristics of the model. After the manufacture and assembly of the machine, experiments on stiffness, accuracy, and machining are carried out. The capability of five-face milling in one setup is verified, and the finished work piece has good surface quality.

The Effect of Base Position on Maximum Allowable Load of Dual Arm Robots

A new computational technique is presented to find the optimal base position of dual arm robots in order to carry maximum allowable load. The maximum allowable load on a desired trajectory is limited by the number of factors such as; actuators torque limits, kinematic constraints, and kinematic redundancy of cooperative manipulators. For a dual arm robot mounted on a rail or table, load workspace (LWS) is introduced as the union of places where the base can locate and robots carry a load on a desired trajectory. It is possible to increase the maximum allowable load by replacing the base of the arms robots in the LWS. By dividing the LWS into grid points, the base position of the rail mounted dual arm robot considered at each point. Using the Newton-Euler formulation and appropriate procedure, maximum allowable load of the robots in all points of the LWS are computed. Then, by iteration a smaller subspace near to optimum base position is selected until maximum allowable load and corresponding base position is found with acceptable precision. Finally, in two different cases the application of the proposed algorithm is presented and verified.

Fault-Tolerant Region-Based Control of an Underwater Vehicle with Kinematically Redundant Thrusters

This paper presents a new control approach for an underwater vehicle with a kinematically redundant thruster system. This control scheme is derived based on a fault-tolerant decomposition for thruster force allocation and a region control scheme for the tracking objective. Given a redundant thruster system, that is, six or more pairs of thrusters are used, the proposed redundancy resolution and region control scheme determine the number of thruster faults, as well as providing the reference thruster forces in order to keep the underwater vehicle within the desired region. The stability of the presented control law is proven in the sense of a Lyapunov function. Numerical simulations are performed with an omnidirectional underwater vehicle and the results of the proposed scheme illustrate the effectiveness in terms of optimizing the thruster forces.

1A1-O05 食器運搬ロボットの手先水平維持時における手先力・モーメント荷重および途中リンク部外力への対応(ホーム&オフィスロボット)

For the service robot which carries dishes at home or a restaurant, supporting different dishes of weight and maintaining the endpoint attitude to external forces acting suddenly on the robot body are required so as not to spill them or harm people. In the paper, it is shown in experiments using a six-joint robot arm that applying an adaptive control for the unknown gravity force-moment load at the endpoint and leaving the kinematic redundancy to the robot arm allow it to safely continue the task even in the situation without any force sensor.

Hybrid Taguchi DNA Swarm Intelligence for Optimal Inverse Kinematics Redundancy Resolution of Six-DOF Humanoid Robot Arms

This paper presents a hybrid Taguchi deoxyribonucleic acid (DNA) swarm intelligence for solving the inverse kinematics redundancy problem of six degree-of-freedom (DOF) humanoid robot arms. The inverse kinematics problem of the multi-DOF humanoid robot arm is redundant and has no general closed-form solutions or analytical solutions. The optimal joint configurations are obtained by minimizing the predefined performance index in DNA algorithm for real-world humanoid robotics application. The Taguchi method is employed to determine the DNA parameters to search for the joint solutions of the six-DOF robot arms more efficiently. This approach circumvents the disadvantage of time-consuming tuning procedure in conventional DNA computing. Simulation results are conducted to illustrate the effectiveness and merit of the proposed methods. This Taguchi-based DNA (TDNA) solver outperforms the conventional solvers, such as geometric solver, Jacobian-based solver, genetic algorithm (GA) solver and ant, colony optimization (ACO) solver.

Deficits in spatial threshold control of muscle activation as a window for rehabilitation after brain injury.

Recovery of voluntary control of movement is the main goal of rehabilitation. Despite numerous studies aimed at identifying the most effective rehabilitation interventions, attempts to improve poststroke upper limb recovery remain disappointing: Sensorimotor deficits of the arm and hand persist in a large proportion of stroke survivors (up to 62 %). Indeed, efforts to improve upper limb recovery have been hampered by the lack of understanding of the neural mechanisms underlying spasticity, muscle weakness, and altered kinematic redundancy. Spasticity refers to the presence of hyperactive velocity-dependent stretch reflexes and is associated with disorders of upper motor neurons following central nervous system (CNS) injury such as stroke. Since it is associated with disruption of upper motor neuron function, those with spasticity typically also have weakness and decreased control of voluntary movements. Despite intensive research into these phenomena, the nature of the relationship and neural mechanisms underlying spasticity, weakness, and voluntary control remains unclear. This chapter will describe a new approach to the understanding of this relationship based on deficits in (1) the ability of the damaged CNS to control spatial thresholds (STs) of reflexes and (2) the residual capacity of corticospinal pathways to regulate STs across different regions of the arm workspace in poststroke subjects at rest and during voluntary movement. This approach is driven by recent evidence that, rather than directly specifying motor commands to muscles, the corticospinal system resets STs of reflexes to generate and control voluntary movement.

Limit Load Evaluation Using the mα-Tangent Multiplier in Conjunction With Elastic Modulus Adjustment Procedure

In this paper, the mα-tangent multiplier is used in conjunction with the elastic modulus adjustment procedure (EMAP) for limit load determination. This technique is applied to a number of mechanical components possessing different kinematic redundancies. By specifying spatial variations in the elastic modulus, numerous sets of statically admissible and kinematically admissible stress and strain distributions are generated, and limit loads for practical components are then determined using the mα-tangent method. The procedure ensures sufficiently accurate limit loads within a reasonable number of iterations. Results are compared with the inelastic finite element results and are found to be in satisfactory agreement.

Effects of a Foot Placement Constraint on Use of Motor Equivalence during Human Hopping

Humans can robustly locomote over complex terrains even while simultaneously attending to other tasks such as accurate foot placement on the ground. We investigated whether subjects would exploit motor redundancy across the joints of the leg to stabilize overall limb kinematics when presented with a hopping task that constrained foot placement position. Subjects hopped in place on one leg (2.2 Hz) while having to place their foot into one of three target sizes upon landing (0.250, 0.063, 0.010 m2). As takeoff and landing angles are critical to this task performance, we hypothesized smaller target sizes would increase the need to stabilize (i.e., make more consistent) the leg orientation through motor equivalent combinations of segment angles. As it was not critical to the targeting task, we hypothesized no changes for leg length stabilization across target size. With smaller target sizes, we saw total segment angle variance increase due to greater signal-dependent noise associated with an increased activation of leg extensor muscles (medial and lateral gastrocnemius, vastus medialis, vastus lateralis and rectus femoris). At smaller target sizes, more segment angle variance was aligned to kinematic deviations with the goal of maintaining leg orientation trajectory. We also observed a decrease in the variance structure for stabilizing leg length at the smallest target conditions. This trade-off effect is explained by the nearly orthogonal relationship between the two goal-equivalent manifolds for leg length vs. leg orientation stabilization. Our results suggest humans increasingly rely on kinematic redundancy in their legs to achieve robust, consistent locomotion when faced with novel conditions that constrain performance requirements. These principles may generalize to other human locomotor gaits and provide important insights into the control of the legs during human walking and running.

Modeling and Control of Head Raising Snake Robots by Using Kinematic Redundancy

In this paper, we consider trajectory tracking control of a head raising snake robot on a flat plane by using kinematic redundancy. We discuss the motion control requirements to accomplish trajectory tracking and other tasks, such as singular configuration avoidance and obstacle avoidance, for the snake robot. The features of the internal motion caused by kinematic redundancy are considered, and a kinematic model and a dynamic model of the snake robot are derived by introducing two types of shape controllable point. The first is the head shape controllable point, and the other is the base shape controllable point. We analyzed the features of the two kinds of shape controllable point and proposed a controller to accomplish the trajectory tracking of the robot's head as its main task along with several sub-tasks by using redundancy. The proposed method to accomplish several sub-tasks is useful for both the kinematic model and the dynamic model. Experimental results using a head raising snake robot which can control the angular velocity of its joints show the effectiveness of the proposed controller.

Grasp planning and parallel control of a redundant dual-arm/hand manipulation system

SUMMARYIn this paper, a kinematic model of a dual-arm/hand robotic system is derived, which allows the computation of the object position and orientation from the joint variables of each arm and each finger as well as from a suitable set of contact variables. On the basis of this model, a motion planner is designed, where the kinematic redundancy of the system is exploited to satisfy some secondary tasks aimed at ensuring grasp stability and manipulation dexterity without violating physical constraints. To this purpose, a prioritized task sequencing with smooth transitions between tasks is adopted. Afterwards, a controller is designed so as to execute the motion references provided by the planner and, at the same time, achieve a desired contact force exerted by each finger on the grasped object. To this end, a parallel position/force control is considered. A simulation case study has been developed by using the dynamic simulator GRASPIT!, which has been suitably adapted and redistributed.

An SVD approach to reaching tasks based on Cartesian geodesics

We are interested in human motion characterization and automatic motion simulation. The apparent redundancy of the humanoid w.r.t its explicit tasks lead to the problem of choosing a plausible movement in the framework of redundant kinematics. This work explores the intrinsic relationships between singular value decomposition at kinematic level and optimization principles at task level and joint level. The ideas are tested on sitting reach motions, for both translations and rotations task components.

Force Maximization of Biarticularly Actuated Manipulators Using Infinity Norm

There is a rising interest in biologically inspired manipulators equipped with biarticular actuators-actuators that span two joints-for solving the known limitations of conventional systems. In contrast with kinematic redundancy, actuator redundancy resulting from the presence of biarticular actuators has the added advantages of bringing more stability, reducing the inertia of the robot links, and decreasing the nonlinearity of the end effector force as a function of force direction. In this paper, the advantage of the infinity norm optimization criteria on a robot designed under the actuator redundancy paradigm is investigated. A closed form solution based on the infinity norm for a manipulator with mono- and biarticular actuators is derived. The proposed infinity norm-based approach is compared with the conventional method based on pseudoinverse matrix by both calculation and experiment. Under the same actuator limitations, the maximum end effector force produced with the proposed method is significantly greater than the one produced by the conventional method. The proposed closed form solution is suitable for redundant systems with three inputs and two outputs, bringing the advantage of an higher maximum output without the need for iterative algorithms.

Biomechanics of Skeletal Muscles

Part I. Muscle Architecture and Mechanics Chapter 1. Muscle Architecture Muscle Fascicles and Their Arrangements * Parallel Fibered and Fusiform Muscles * Pennate Muscles * Convergent and Circular Muscles Muscle Fascicle Curvature: Frenet Frames Fiber Architecture in the Fascicles Muscle as a Fiber-Reinforced Composite Fiber, Fascicle, and Muscle Length: Length-Length Ratios * Fiber and Fascicle Length * Length-Length Ratios Muscle Path: Muscle Centroids * Straight-Line Representation of Muscle Path * Centroid Model of Muscle Path * Curved and Wrapping Muscles * Twisted Muscles * Muscles Attaching to More Than Two Bones Cross-Sectional Area, Physiological and Anatomical Muscle Attachment Area Summary Questions for Review Literature List Chapter 2. Properties of Tendons and Passive Muscles Biomechanics of Tendons and Aponeuroses * Elastic Behavior * Viscoelastic Behavior of Tendons * Tendon Interaction With Surrounding Tissues Mechanical Properties of Passive Muscles * Muscle Tone: Equitonometry * Mechanical Properties of Relaxed Muscles On Joint Flexibility Summary Questions for Review Literature List Chapter 3. Mechanics of Active Muscle Muscle Force Production and Transmission * Experimental Methods * Transition From Rest to Activity * Transition From Activity to Rest: Muscle Relaxation * Constancy of the Muscle Volume * Force Transmission and Internal Deformations (Strain) * Intramuscular Stress and Pressure * Functional RelationsForce-Length Relations * Force-Velocity Relations * Force-Length-Velocity Relations History Effects in Muscle Mechanics * Force Depression After Muscle Shortening * Effects of Muscle Release: Quick-Release and Controlled-Release Methods: Series Muscle Components Summary Questions for Review Literature List Chapter 4. Muscles as Force and Energy Absorbers Muscle Mechanical Behavior During Stretch * Dynamic Force Enhancement * Residual Force Enhancement Muscle Shortening After Stretch * Work and Power During Shortening After Stretch * Energy Consumption During Stretch and Efficiency of the Muscle Shortening After Stretch Dissipation of Energy Mechanical Muscle Models * Hill-Type Model * Model Scaling Summary Questions for Review Literature List Part II Muscles in the Body Chapter 5. From Muscle Forces to Joint Moments Force Transmission: From Muscle to Bone * From Muscle to Tendon * From Tendon to Bone * Tendon Elasticity and Isometric Force-Length Relation Force Transmission Via Soft Tissue Skeleton (Fascia) * Structure of Fascia * Muscle-Tendon-Fascia Attachments * Fascia as Soft Tissue Skeleton (Ectoskeleton) Muscle Moment Arms * Muscle Moment Arm Vectors and Their Components * Methods for Determination of Muscle Moment Arms * Factors Affecting Muscle Moment Arm * Transformation of Muscle Forces to Joint Moments: Muscle Jacobian Summary Questions for Review Literature List Chapter 6. Two-Joint Muscles in Human Motion Two-Joint Muscles: A Special Case of Multifunctional Muscles * Functional Features of Two-Joint Muscles * Anatomical and Morphological Features of Two-Joint Muscles Functional Roles of Two-Joint Muscles * Kinetic Analysis of Two-Joint Muscles: Lombard's Paradox * Kinematic Analysis of Two-Joint Muscles: Solution of Lombard's Paradox Mechanical Energy Transfer and Saving by Two-Joint Muscles * Tendon Action of Two-Joint Muscles * Saving Mechanical Energy by Two-Joint Muscles Summary Questions for Review Literature List Chapter 7. Eccentric Muscle Action in Human Motion Joint Power and Work as Measures of Eccentric Action * Negative Power and Work at a Joint * Total Negative Power and Work in Several Joints * Negative Power of Center of Mass Motion * Two Ways of Mechanical Energy Dissipation: Softness of Landing Negative Work in Selected Activities * Walking * Stair Descent and Ascent * Level, Downhill, and Uphill Running * Landing Joint Moments During Eccentric Actions * Maximal Joint Moments During Eccentric Actions * Force Changes During and After Stretch * Residual Force Enhancement in Humans Muscle Activity During Eccentric Actions * Surface Electromyographic Activity During Eccentric Actions * Motor Unit Activity During Eccentric Actions * Electromechanical Delay Physiological Cost of Eccentric Action * Oxygen Consumption During Eccentric and Concentric Exercise * Fatigue and Perceived Exertion During Eccentric Action * Muscle Soreness After Eccentric Exercise Reversible Muscle Action: Stretch-Shortening Cycle * Enhancement of Positive Work and Power Production * Mechanisms of the Performance Enhancement in the SSC * Efficiency of Positive Work in SSC Summary Questions for Review Literature List Chapter 8. Muscle Coordination in Human Motion Kinematic Redundancy and Kinematic Invariant Characteristics of Limb Movements * Straight-Line Limb Endpoint Trajectory * Bell-Shaped Velocity Profile8.1.3 Power Law * Fitts' Law * Principle of Least Action Kinetic Invariant Characteristics of Limb Movements * Elbow-Shoulder Joint Moment Covariation During Arm Reaching * Minimum Joint Moment Change * Orientation and Shape of the Arm Apparent Stiffness Ellipses Muscle Redundancy * Sources of Muscle Redundancy * Invariant Features of Muscle Activity Patterns The Distribution Problem * Static Optimization * Dynamic Optimization * Inverse Optimization * On Optimization Methods in Human Biomechanics and Motor Control Summary Questions for Review Literature List