Joint Coordinate System Research Articles

Application of the joint coordinate system to three-dimensional joint attitude and movement representation: a standardization proposal.

The selection of an appropriate and/or standardized method for representing 3-D joint attitude and motion is a topic of popular debate in the field of biomechanics. The joint coordinate system (JCS) is one method that has seen considerable use in the literature. The JCS consists of an axis fixed in the proximal segment, an axis fixed in the distal segment, and a "floating" axis. There has not been general agreement in the literature on how to select the body fixed axes of the JCS. The purpose of this paper is to propose a single definition of the body fixed axes of the JCS. The two most commonly used sets of body fixed axes are compared and the differences between them quantified. These differences are shown to be relevant in terms of practical applications of the JCS. Argumentation is provided to support a proposal for a standardized selection of body fixed axes of the JCS consisting of the axis ê1 embedded in the proximal segment and chosen to represent flexion-extension, the "floating" axis ê2 chosen to represent ad-abduction, and the axis ê3 embedded in the distal segment and chosen to represent axial rotation of that segment. The algorithms for the JCS are then documented using generalized terminology.

An integrated procedure to assess knee-joint kinematics and kinetics during gait using an optoelectric system and standardized X-rays

This paper describes a 3-D gait analysis system, which combines optoelectric motion tracking and a standardized X-ray procedure, to calculate the net knee-joint forces and moments of a normal subject group during walking. The optoelectric system collects kinematic data from infra-red LED markers placed at selected skin surface locations and projecting probes attached to the lower limb. A standardized X-ray procedure is used to move surface markers into their designated bony landmarks based on individual bone structure, which reduces the error caused by uncertainty of skin-surface marker locations. Based on moved-in marker information, different joint coordinate systems are proposed for kinematic and kinetic analysis of the knee joint. Normalized data of knee angles, net reaction forces and net moments from 35 young, normal subjects are presented.

Effects of arch height of the foot on angular motion of the lower extremities in running

It has been suggested that a relationship exists between the height of the medial longitudinal arch of the foot and athletic injuries to the lower extremities. However, the functional significance of arch height in relation to injury is not well understood. The purpose of this study was to determine the influence of arch height on kinematic variables of the lower extremities that have been associated with the incidence of injury in running in an attempt to gain some insight into a functional relationship between arch height and injury. The three-dimensional kinematics of the lower extremities were measured during running for 30 subjects using high-speed video cameras. A joint coordinate system was used to calculate the three-dimensional orientation of the ankle joint complex for a single stance phase. Simple, linear regression analyses showed that arch height does not influence either maximal eversion movement or maximal internal leg rotation during running stance. However, assuming that knee pain in running can result from the transfer of foot eversion to internal rotation of the tibia, a functional relationship between arch height and injury may exist in that the transfer of foot eversion to internal leg rotation was found to increase significantly with increasing arch height. A substantial (27%), yet incomplete, amount of the variation in the transfer of movement between subjects was explained by arch height, indicating that there must be factors other than arch height that influence the kinematic coupling at the ankle joint complex. Additionally, the transfer of movement is only one factor of many associated with the etiology of knee pain in running. Therefore, it is suggested that a running-injury-related foot typology based on arch height is not possible at this time.

Three-dimensional kinematics of the human knee during walking

Three-dimensional kinematics of the tibiofemoral joint were studied during normal walking. Target markers were fixed to tibia and femur by means of intra-cortical traction pins. Radiographs of the lower limb were obtained to compute the position of the target markers relative to internal anatomical structures. High-speed cine cameras were used to measure three-dimensional coordinates of the target markers in five subjects walking at a speed of 1.2 m s −1. Relative motion between tibia and femur was resolved according to a joint coordinate system (JCS). The measurements have identified that substantial angular and linear motions occur about and along each of the JCS axes during walking. The results do not, however, support the traditional view that the so-called ‘screw home’ mechanism of the knee joint operates during gait.

Dynamics of Flexible Bodies Using Generalized Newton-Euler Equations

A force acting on a rigid body produces a linear acceleration for the whole body together with an angular acceleration about its center of mass. This result is in fact Newton-Euler equations which are used as basis for developing many recursive formulations for open loop multibody systems consisting of interconnected rigid bodies. In this paper, generalized Newton-Euler equations are developed for deformable bodies that undergo large translational and rotational displacements. The configuration of the deformable body is identified using coupled sets of reference and elastic variables. The nonlinear generalized Newton-Euler equations are formulated in terms of a set of time invariant scalars and matrices that depend on the spatial coordinates as well as the assumed displacement field. A set of intermediate reference frames having no mass or inertia are introduced for the convenience of defining various joints between interconnected deformable bodies. The use of the obtained generalized Newton-Euler equations for developing recursive dynamic formulation for open loop deformable multibody systems containing revolute, prismatic and cylindrical joints is also discussed. The development presented in this paper demonstrates the complexities of the formulation and the difficulties encountered when the equations of motion are defined in the joint coordinate systems.

Kinematic Calibration of Robotic Manipulators

A kinematic calibration model for serial robotic manipulators is presented. This model is based on the zero position analysis method, and is not prone to the difficulties encountered in case of parallel or near parallel joints when using joint coordinate system notations. The convergence and effectiveness of the model are demonstrated by numerical simulations.

An assembly modelling system for dynamic and kinematic analysis

An assembly modelling system, with which a designer can interactively create an assembly of components ready for dynamic analysis, has been developed. In this system, an assembly model is created from the mating conditions between the components in the assembly, and then most of the information required for the dynamic or kinematic analysis packages is derived. For this development, the following problems have been solved: creation of assembly data structure, structuring of assembly data, derivation of joint information, inference of each component's position, and creation of joint coordinate systems. Through this work, the designer can easily model an assembly by assigning mating conditions, and check the dynamic or kinematic performance with the automatic creation of inputs for the assembly analysis packages.

The three-dimensional kinematics and flexibility characteristics of the human ankle and subtalar joints--Part I: Kinematics.

The in-vitro, three dimensional kinematic characteristics of the human ankle and subtalar joint were investigated in this study. The main goals of this investigation were: 1) To determine the range of motion of the foot-shank complex and the associated range of motion of the ankle and subtalar joints; 2) To determine the kinematic coupling characteristics of the foot-shank complex, and 3) To identify the relationship between movements at the ankle and subtalar joints and the resulting motion produced between the foot and the shank. The tests were conducted on fifteen fresh amputated lower limbs and consisted of incrementally displacing the foot with respect to the shank while the motion of the articulating bones was measured through a three dimensional position data acquisition system. The kinematic analysis was based on the helical axis parameters describing the incremental displacements between any two of the three articulating bones and on a joint coordinate system used to describe the relative position between the bones. From the results of this investigation it was concluded that: 1) The range of motion of the foot-shank complex in any direction (dorsiflexion/plantarflexion, inversion/eversion and internal rotation/external rotation) is larger than that of either the ankle joint or the subtalar joint.; 2) Large kinematic coupling values are present at the foot-shank complex in inversion/eversion and in internal rotation/external rotation. However, only a slight amount of coupling was observed to occur in dorsiflexion/plantarflexion.; 3) Neither the ankle joint nor the subtalar joint are acting as ideal hinge joints with a fixed axis of rotation.; 4) Motion of the foot-shank complex in any direction is the result of rotations at both the ankle and the subtalar joints. However, the contribution of the ankle joint to dorsiflexion/plantarflexion of the foot-shank complex is larger than that of the subtalar joint and the contribution of the subtalar joint to inversion/eversion is larger than that of the ankle joint.; 5) The ankle and the subtalar joints have an approximately equal contribution to internal rotation/external rotation movements of the foot-shank complex.

Analysis of foot motion during running using a joint co-ordinate system

The amount and rate of pronation and supination have been the subject of interest to runners for some time. Exact determination of the motions has been hampered by their complexities and use of a two-dimensional data collection protocol. "Rearfoot motion," measured by determining the projection of the angle between a line on the posterior of the shank and a line on the heel, has been a common approach. This projection measures a rotation about a laboratory axis and not a body segment axis and has a potential of error due to projection onto a plane. The angle measured in rearfoot motion is not the true angle between these lines in space and has projection distortion errors which are compounded during plantar and dorsiflexion and medial and lateral foot rotations. The rearfoot motion angle, however, does approximate foot inversion-eversion during much of stance phase. The proposed change in research protocol allows analysis of the three-dimensional position data of targets to construct a "joint coordinate system" which gives more accurate data on inversion-eversion and data on plantar-dorsiflexion and medial-lateral rotation of the foot. This analysis may allow the examination of measurable differences between individuals and running shoes of various design.

Experiments on manipulator gross motion using self‐tuning controller and visual information

AbstractA picture of a scene is used to extract information for an adaptive control algorithm. The object of interest is first located by means of a classifier. The position and orientation of the object are determined from a binary picture. The desired path that the gripper of the manipulator is to follow is specified by discrete points, first in the Cartesian and then in the joint coordinate system. The adaptive self‐tuning controller is outlined. The controller design is based on a time series difference equation model in which the parameters are estimated on‐line. The gains of the controller are tuned so that a quadratic performance criterion is minimized. The performance of the system designed is then tested experimentally, and the results are presented.

A joint coordinate system for the clinical description of three-dimensional motions: application to the knee.

The experimental study of joint kinematics in three dimensions requires the description and measurement of six motion components. An important aspect of any method of description is the ease with which it is communicated to those who use the data. This paper presents a joint coordinate system that provides a simple geometric description of the three-dimensional rotational and translational motion between two rigid bodies. The coordinate system is applied to the knee and related to the commonly used clinical terms for knee joint motion. A convenient characteristic of the coordinate system shared by spatial linkages is that large joint displacements are independent of the order in which the component translations and rotations occur.

Industrial Manipulator Control Using Kalman Filter and Adaptive Controller

The use of Kaiman fitter in conjunction with adaptive controller is proposed to control the positions and velocities of the joints in a manipulator.The dynamics of a joint of a robotic manipulator are modelled by using a set of difference equations. The parameters of the model for the motion of a joint are estimated on-line by using a Kaiman filter. An adaptive controller is designed for each joint so as to make the position and velocities of the joint follow a prespecified path in the joint coordinate system. The algorithms for the parameter estimation and computation of the controller gains are presented. Digital simulation results demonstrate the applicability of the approach to control the motion of a manipulator.

Methods for Optimal Guidance of Industrial Robot Motions

Industrial robots are used in a number of very different tasks. Typical applications are spot welding, arc welding, assembly, painting, material handling. Therefore application flexibility is a key concept for an industrial robot. Application flexibility of a robot is greatly enhanced by the use of fast and easy methods of teaching the robot. This paper deals with a new man-machine interface for teaching robots. At our institute a colour-screen-system with light pen has been developed. This system is used for the definition of the work flow at workpiece handling from a moving conveyor to the place of deposit. With this system the operator can draw instructions over a real video frame showing the robot and the working place. Possible instructions are obstacles or intermediate positions of the robot path. A first realization was done with one camera at the ceiling.A further crucial point treated in this paper is the calculation of robot paths. Depending on intermediate path points, forbidden areas and given velocities the paths of robot motions are computed. The computation algorithm gets its input data from the teaching informations as well as from an optical sensor, which recognizes position and orientation of a workpiece on a moving conveyor. Because the calculation of robot paths is done in joint coordinates transformations from “world ”-coordinate systems (teaching and sensor coordinate systems) into the joint coordinate system are necessary. For the trajectories of the robot motions polynomials are determined. Determining these polynomials various optimisation criteria (length, time, energy consumption, minimum stress imposed on material) can be taken into consideration. The calculations for the optimal guidance of robots are done by a microprocessor, which is a part of a distributed microprocessor system.