Maximum Joint Torque Research Articles

Comparing different approaches for determining joint torque parameters from isovelocity dynamometer measurements

Strength, or maximum joint torque, is a fundamental factor governing human movement, and is regularly assessed for clinical and rehabilitative purposes as well as for research into human performance. This study aimed to identify the most appropriate protocol for fitting a maximum voluntary torque function to experimental joint torque data. Three participants performed maximum isometric and concentric–eccentric knee extension trials on an isovelocity dynamometer and a separate experimental protocol was used to estimate maximum knee extension angular velocity. A nine parameter maximum voluntary torque function, which included angle, angular velocity and neural inhibition effects, was fitted to the experimental torque data and three aspects of this fitting protocol were investigated. Using an independent experimental estimate of maximum knee extension angular velocity gave lower variability in the high concentric velocity region of the maximum torque function compared to using dynamometer measurements alone. A weighted root mean square difference (RMSD) score function, that forced the majority (73–92%) of experimental data beneath the maximum torque function, was found to best account for the one-sided noise in experimental torques resulting from sub-maximal effort by the participants. The suggested protocol (an appropriately weighted RMSD score function and an independent estimate of maximum knee extension angular velocity) gave a weighted RMSD of between 11 and 13Nm (4−5% of maximum isometric torque). It is recommended that this protocol be used in generating maximum voluntary joint torque functions in all torque-based modelling of dynamic human movement.

분산 구동 메커니즘을 내장한 로봇 핑거의 정밀 자세 제어기 설계

In this paper, we newly propose a novel control strategy of a three joints-robot finger for the purpose of artificial hands. The robot finger is specifically modeled by using a 3D CAD program (CATIA), considering human fingers, and then the proposed control method is verified through the dynamic simulation tool (Simulink and Recurdyn R2). Each slider is individually controlled to be located at the optimal positions where the maximal joint torque can be generated. To prove the effectiveness of the proposed control method, we devise two cases for the reference position of sliders. By comparing the control performance of two cases, the validity of the proposed control method will be verified.

66847 Biomechanical Analysis of Steering Motion Using Motion Analysis Technique(Biomechanics)

Using motion analysis technique, kinematics of steering motion as well as dynamic nature of steering motion are analyzed. During steering motion elbow pronation-supination, wrist flexion-extension, shoulder adduction-abduction, shoulder flexion-extension are major motion. For ±40° of steering wheel angle, elbow flexion-extension is the most sensitive to design parameters associated with steering wheel and seating configuration. Also through dynamic analysis, maximum joint torque is calculated and the results are compared with known values, which showed somewhat smaller values due to the multi joint evolvement of steering motion. Also there is some angle that each joint torque becomes maximum and minimum. The results can be applied to the steering system design as well as steering torque generation algorithm for active control of steering wheel.

Maximum voluntary joint torque as a function of joint angle and angular velocity: Model development and application to the lower limb

Measurements of human strength can be important during analyses of physical activities. Such measurements have often taken the form of the maximum voluntary torque at a single joint angle and angular velocity. However, the available strength varies substantially with joint position and velocity. When examining dynamic activities, strength measurements should account for these variations. A model is presented of maximum voluntary joint torque as a function of joint angle and angular velocity. The model is based on well-known physiological relationships between muscle force and length and between muscle force and velocity and was tested by fitting it to maximum voluntary joint torque data from six different exertions in the lower limb. Isometric, concentric and eccentric maximum voluntary contractions were collected during hip extension, hip flexion, knee extension, knee flexion, ankle plantar flexion and dorsiflexion. Model parameters are reported for each of these exertion directions by gender and age group. This model provides an efficient method by which strength variations with joint angle and angular velocity may be incorporated into comparisons between joint torques calculated by inverse dynamics and the maximum available joint torques.

A Study on Evaluation of the Manipulation Ability of the Upper Limb Using Convex Polyhedron (1st Report, New Vertex Search Algorithm)

In this paper, we have applied the analysis method for the robot manipulators to the evaluation of the manipulation ability of the human upper limb. The set of maximum hand force based on individual's muscular power characteristics were expressed in the six-dimensional convex polyhedron (Manipulating Force Polyhedron). The spatial characteristic of the manipulation ability of the upper limb in three-dimensional space was clarified by the visualization of the six-dimensional convex polyhedron using a new vertex search algorithm. In order to show the effectiveness of the proposed method, we compared manipulating force polyhedron with measured maximum hand force. The manipulating force polyhedron was calculated from measured maximum joint torque of the upper limb depending on joint angle and rotation direction. Our evaluation method will be useful not only for the evaluation of the manipulation ability of the upper limb but also for the development of equipment based on individual's muscular power characteristics.

Geometrically accurate biological flow simulation: applications to pine cone pollination and graptolite hydrodynamics

Objective: Restoration of stand-up motion in patients with complete paraplegia utilizing multichannel functional electrical stimulation, and analysis of the restored motion. Design: Nonrandomized control trial. Setting: General community, a referral center, institutional practice, and ambulatory care. Patients: Twelve volunteer samples were used for the collection of normal data. Two complete paraplegics received treatment for the restoration of stand-up motion. Main Outcome Measures: The electromyogram, joint angle, and floor reaction force were investigated during standing-up with arms crossed in front of the chest, and hands-assisted standing-up using parallel bars. The maximum knee joint torque during standing-up without hands-assists was calculated using a three-segment link model. Standing-up motion in complete paraplegics was restored, and then analyzed using the three-dimensional floor reaction force and the hip, knee, and ankle angles. Results: Main muscles used to stand up were the quadriceps, tibialis anterior, and paraspinal muscles. Hands-assists reduced the muscle activity and the vertical floor reaction force. Peak muscle activity was less during hands-assisted standing-up, except for the rectus femoris and the iliopsoas muscle. The maximum knee joint torque during standing-up was 1.6Nm/kg for both knees. Two complete paraplegics were able to stand up smoothly from a wheelchair based on stimulation data obtained from normal subjects. The characteristic pattern during standing-up was knee flexion preceding extension. Conclusion: Stand-up motion was restored utilizing electromyogram data and knee joint torque data from normal subjects.

Effects Of Aerobic Training Programs On Maximal Joint Torque And Muscular Endurance In Senior Women

PURPOSE To compare the effectiveness of aerobic exercise programs based on two training modes: intermittent vs continuous and two types of activity: walking and stepups, on maximal joint torque and muscular endurance, in 135 community-dwelling women aged 55–77. METHODS A 42-week prospective study with assessments at baseline (T0), after a 12-week exercise program (1 session/week) (T1), and 30 weeks after the program (T2), was investigated. Individuals were randomly assigned to one of five groups depending on the training program: continuous walking (near 80% maximal heart rate (HRmax)) (n = 43; 65.7 ± 5.0 yr), intermittent walking (near HRmax) (n = 44; 65.9 ± 3.8 yr), continuous step-ups (near 80% HRmax) (n = 23; 64.5 ± 4.0 yr), intermittent step-ups (near HRmax) (n = 13; 64.8 ± 2.9 yr) and control (n = 12; 65.6 ± 4.3 yr). Fat-free thigh volume (FFV) was estimated by anthropometric measurements. Maximal joint torque (MJT) of lower-limbs extensors was assessed with a force transducer. Muscular endurance (ME) was expressed as percentages of joint torque decrease during two exercises of 60 sec: a maximal continuous contraction and repeated maximal contractions of 2 sec separated by 3 sec of relaxation. RESULTS At T0, no significant difference was observed between the five studied groups. MJT was poorly related to FFV (r2<0.07, p<0.05). MJT of right lower-limb was significantly greater than MJT of left lower-limb (p<0.001). No significant MJT and ME improvement was observed from T0 to T2. CONCLUSION Whatever training mode and type of activity, aerobic exercise programs did not lead any maximal joint torque and muscular endurance improvements. The small number o training sessions and the non specificity (compared with musculation) of the exercise programs could explain these results. Supported by the FFEPGV (French Federation of Physical Education and Voluntary Gymnastics), the Auvergne DRJS (Regional Direction of Youth and Sports), the AFRAPS (French Association for Research in Physical and Sportive Activity), and the CREAS (Auvergne Executive Committee for Health Actions).

Effects Of Aerobic Training Programs On Maximal Joint Torque And Muscular Endurance In Senior Women

PURPOSE To compare the effectiveness of aerobic exercise programs based on two training modes: intermittent vs continuous and two types of activity: walking and stepups, on maximal joint torque and muscular endurance, in 135 community-dwelling women aged 55–77. METHODS A 42-week prospective study with assessments at baseline (T0), after a 12-week exercise program (1 session/week) (T1), and 30 weeks after the program (T2), was investigated. Individuals were randomly assigned to one of five groups depending on the training program: continuous walking (near 80% maximal heart rate (HRmax)) (n = 43; 65.7 ± 5.0 yr), intermittent walking (near HRmax) (n = 44; 65.9 ± 3.8 yr), continuous step-ups (near 80% HRmax) (n = 23; 64.5 ± 4.0 yr), intermittent step-ups (near HRmax) (n = 13; 64.8 ± 2.9 yr) and control (n = 12; 65.6 ± 4.3 yr). Fat-free thigh volume (FFV) was estimated by anthropometric measurements. Maximal joint torque (MJT) of lower-limbs extensors was assessed with a force transducer. Muscular endurance (ME) was expressed as percentages of joint torque decrease during two exercises of 60 sec: a maximal continuous contraction and repeated maximal contractions of 2 sec separated by 3 sec of relaxation. RESULTS At T0, no significant difference was observed between the five studied groups. MJT was poorly related to FFV (r2<0.07, p<0.05). MJT of right lower-limb was significantly greater than MJT of left lower-limb (p<0.001). No significant MJT and ME improvement was observed from T0 to T2. CONCLUSION Whatever training mode and type of activity, aerobic exercise programs did not lead any maximal joint torque and muscular endurance improvements. The small number o training sessions and the non specificity (compared with musculation) of the exercise programs could explain these results. Supported by the FFEPGV (French Federation of Physical Education and Voluntary Gymnastics), the Auvergne DRJS (Regional Direction of Youth and Sports), the AFRAPS (French Association for Research in Physical and Sportive Activity), and the CREAS (Auvergne Executive Committee for Health Actions).

歩行椅子用パワーアシスト駆動系の開発 : 人間のクランク駆動特性(S47-2 福祉機器,S47 健康・福祉機器の開発)

alternative vehicle of a wheel chair that is driven by human cranking and actuators. One of the requirement to a power assisting system of the walking chair is that human power is utilized as much as possible while long distance movement can be achieved without much fatigue by human, hi this paper, we investigated kinetostatic characteristics of upper part of a human body through experiment. We proposed a model composed of 3-dof translations associated with the shoulder. 3-dof rotations associated with upper arm's flexion-extension, abduction-adduction and rotation, and a single dof associated with elbow's bending and stretching, hi the model, constraints on the maximum joint torque have been introduced in simultaneous actuation of multiple joints. Then, we applied the proposed model to design an appropriate axis position of the crank driven by human.

Three-Dimensional Spatial Expression of the Manipulation Ability of the Upper Limb Considering Asymmetry of Maximum Joint Torque

In order to evaluate the manipulation ability of the upper limb, we applied the analysis of the mechanism of robot manipulators. The effect of individual's muscular power characteristics on the easiness of hand force manipulation is expressed in the six-dimensional ellipsoid. The spatial characteristic of the manipulation ability of the upper limb in three-dimensional space was clarified by the visualization of the six-dimensional ellipsoid using two projection methods. As examples, we analyzed wheelchair propulsion, then the effectiveness of our evaluation methods were examined. Our evaluation methods will be useful for the development of equipments based on the manipulation ability of the upper limb.

Fatigue induced changes in phasic muscle activation patterns for fast elbow flexion movements.

The present study investigated how muscle fatigue influences single degree-of-freedom elbow flexion movements and their associated patterns of phasic muscle activation. Maximal unfatigued voluntary isometric elbow flexor and extensor joint torque was measured at the beginning of the experiment. Subjects then performed elbow flexion movements over two distances as fast as possible, and movements over the longer distance at an intentionally slower speed. The slower speed was close to what would become the maximal speed in the fatigued state. Subjects then performed a fatiguing protocol of 20 sustained isometric flexion contractions of 25 s duration with 5 s rest at 50% maximal unfatigued voluntary force. After a recovery period they repeated the movements. The fatigue protocol was successful in inducing muscle fatigue, the evidence being decreased isometric maximal joint torque of over 20%. Fatigued movements had lower peak muscle torque and speed. Our principal finding was of changes in the timing of the phasic patterns of fatigued muscle activation. There was an increase in the duration of the agonist burst and a delay in the timing of the antagonist muscle as measured by the centroid of the EMG signals. We conclude that these changes serve as partial but incomplete, centrally driven compensation for fatigue induced changes in muscle function. An additional, unexpected finding was how small an effect fatigue had on movement performance when using a recovery time of 10 min that is long enough to allow muscle membrane conduction velocity to return to normal. This raises questions concerning the behavioral significance of classical laboratory studies of human fatigue mechanisms.

Dynamic performance analysis of six-legged walking machines

The aim of this article is to provide a systematic method to perform dynamic analysis in the task space for walking machine. The dynamic manipulability ellipsoid is introduced and the two quantitative indices of the walking machine's capability, in each configuration, of performing main-body accelerations along given task space directions are defined. The ellipsoids are derived on the basis of the mapping of the body accelerations onto the joint driving torques (including the selected generalized joints’ driving torques and non-generalized joints’ driving torques) via the proper dynamic coordination and optimal dynamic load distribution equations of the walking machine. The maximum joint torque limits are taken into account. In the final, a numerical example is given to indicate the use of the indices in the optimal designing of walking machine's mechanism parameters.

An Investigation of the Relationship between Hip Extension Torque, Hip Extension Velocity, and Muscle Activation

The purpose of this study was to determine if the characteristic Hill model, used to describe me force–velocity relationship for isolated tetanically stimulated muscle, could be modified and used to describe me torque–velocity behavior of me hip for maximally and submaximally stimulated hip extensor muscles. Fourteen subjects performed hip extension movements at effort levels of 100%, 70%, and 40% of a maximum isometric effort. A solenoid provided isometric resistance to hip extension. Once the desired effort level was achieved, as indicated by me isometric force, the solenoid released and me hip moved against an opposing elastic resistance equal to 75%, 50%, 25%, and 0% of the specified effort level. An electrogoniometer quantified hip angle. Hip velocity was determined by numerically differentiating the angle data. Torque-velocity-activation (or effort level) data were determined for each trial. Model parameters were determined to give me best fit to the data for each subject. Average parameter values were determined for each gender and for the entire group. The modified Hill-type model, Tm = (Tmax · A − K1 · ω)/(K2 · ω + 1), accurately describes me relationship between joint torque (Tm), maximum isometric joint torque (Tmax), joint velocity (ω), and muscle activation level (A) for subject-specific parameters (K1 and K2), but not for parameters averaged across genders or the entire group. Values for Tmax, K1, and K2 ranged from 90 to 385 Nm, 6.1 to 47.9 Nms, and 0.030 to 0.716 s, respectively.

A fully neural-network-based planning scheme for torque minimization of redundant manipulators

The aim of this paper is to develop a new method for minimizing joint torques of redundant manipulators in the Chebyshev sense and to present a fully neural-network-based computational scheme for its implementation. Minimax techniques are used to determine the null space acceleration vector which can guarantee to minimize the maximum joint torque. For real-time implementation, we transform the proposed method into a computation of a recurrent neural network. At each time step, the neural network is adopted for both the solution of the least-norm joint acceleration and the determination of the optimum null space acceleration vector. Compared with previous torque minimization schemes, the proposed method enables more direct monitoring and control of the magnitudes of the individual joint torques than does the minimization of the sum of squares of the components. Simulation results demonstrate that the proposed method is effective for the torque minimization control of redundant manipulators.

Evaluation of isometric antagonist coactivation strategies of electrically stimulated muscles.

The performance of various coactivation strategies to control agonist-antagonist muscles in functional electrical stimulation (FES) applications was examined in a cat model using the tibialis anterior and soleus muscles to produce ankle isometric dorsiflexion and plantarflexion torques, respectively. Three types of coactivation strategies were implemented and tested. The first strategy was based on coactivation maps described in the literature as consisting of decreasing antagonistic activity as the input command to the agonist was increased. The second type of strategy was based on the physiologic coactivation data collected from normal subjects exhibiting joint stabilization during the full range of contractions. These strategies included scaled increasing antagonist activity and therefore joint stiffness with increasing agonist input command. A third strategy was devised which at low force levels mimicked the strategies described in the literature and at high force levels resembled strategies exhibited by normal subjects. The three strategies were evaluated based on their ability to track a linear or sinusoidal input command and their efficiency of torque transmission across the joint. Coactivation strategies using increasing antagonist activity resulted in decreased maximal joint torque and efficiency, decreased signal tracking capability for linear inputs, and increased harmonic distortion for sinusoidal inputs. Peak efficiency and tracking ability appeared when a moderate degree of antagonist activity was engaged near the neutral joint position. Signal tracking quality improved with earlier engagement of the antagonist muscles. Our results suggest that strategies combining low-level coactivation as described in the physiological literature and previous FES studies could satisfactorily address the issues of controllability, efficiency, and long-term joint integrity.

Restoration and analysis of standing-up in complete paraplegia utilizing functional electrical stimulation

Objective: Restoration of stand-up motion in patients with complete paraplegia utilizing multichannel functional electrical stimulation, and analysis of the restored motion. Design: Nonrandomized control trial. Setting: General community, a referral center, institutional practice, and ambulatory care. Patients: Twelve volunteer samples were used for the collection of normal data. Two complete paraplegics received treatment for the restoration of stand-up motion. Main Outcome Measures: The electromyogram, joint angle, and floor reaction force were investigated during standing-up with arms crossed in front of the chest, and hands-assisted standing-up using parallel bars. The maximum knee joint torque during standing-up without hands-assists was calculated using a three-segment link model. Standing-up motion in complete paraplegics was restored, and then analyzed using the three-dimensional floor reaction force and the hip, knee, and ankle angles. Results: Main muscles used to stand up were the quadriceps, tibialis anterior, and paraspinal muscles. Hands-assists reduced the muscle activity and the vertical floor reaction force. Peak muscle activity was less during hands-assisted standing-up, except for the rectus femoris and the iliopsoas muscle. The maximum knee joint torque during standing-up was 1.6Nm/kg for both knees. Two complete paraplegics were able to stand up smoothly from a wheelchair based on stimulation data obtained from normal subjects. The characteristic pattern during standing-up was knee flexion preceding extension. Conclusion: Stand-up motion was restored utilizing electromyogram data and knee joint torque data from normal subjects.

Errors in alignment of center of pressure and foot coordinates affect predicted lower extremity torques

The purpose of the study was to quantify the effect of errors in spatial alignment between the center of pressure recorded from a force platform and the coordinates of the foot recorded from film on resultant joint torques in the lower extremity during the stance phase of gait. Two-dimensional kinematic and kinetic data from eight subjects performing walking and running were analyzed using inverse dynamics with the obtained center of pressure values and with ±0.5 and ±1.0 cm shifts in the anteroposterior location of the center of pressure under the support foot. Shifting the center of pressure posteriorly increased the flexor (dorsiflexor) torques at the hip and ankle and decreased the extensor (plantarflexor) torques at these joints. This shift also caused an increase in the extensor and a decrease in the flexor torques at the knee. Shifting the center of pressure anteriorly caused the opposite effects at each joint. The ±0.5 and ±1.0 cm shifts in the location of the center of pressure caused, on average, 7 and 14% changes, respectively, in maximum joint torque and angular impulse values. Relative transition times between flexor and extensor torques were either increased or decreased, on average, by 7 and 13%, respectively for the two conditions over all trials. Based on these results, it is concluded that due to potential errors in the spatial alignment of kinetic and kinematic data, joint torques in the literature on gait should be considered as approximations of the true values.

Comparison of local and global solution in optimisation of joint torques of n-R planar manipulator

The motion of a 2-R planar manipulator is considered in the operation of weight lifting when the cost function contains a square norm of the lifting height and the joint torques. It is observed that the difference of the paths produced by the global and by the local optimisation can be neglected in most of the cases even though it appears close to the maximum joint torques.

Task Space Dynamic Analysis of Multiarm System Configurations

The aim of this article is to provide a systematic method to perform dynamic analysis in the task space for a sys tem composed of multiple arms holding a rigid object. The dynamic manipulability ellipsoid is introduced to obtain quantitative indices of the system's capability, in each configuration, of performing object accelerations along given task space directions. The ellipsoid is derived on the basis of the mapping of object accelerations onto joint driving torques via the proper kineto-static and dynamic equations of the system. The maximum joint torque limits are taken into account, and the effects of gravitational loads onto the ellipsoid are evidenced. Anal ysis of multiarm system configurations is carried out in a number of case studies.