A kinematic model of the shoulder complex to evaluate the arm-reachable workspace

Klopčar, Nives; Tomšič, Martin; Lenarčič, Jadran

doi:10.1016/j.jbiomech.2005.11.010

Cited by 79 publications

(48 citation statements)

References 9 publications

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“…Reachable workspace describes the volume within which an individual can reach and it is important in the objective assessment and rehabilitation of patients with upper-limb pathology. 10 Clinical observation would suggest tendon transfer surgery increases reachable workspace but the extent and location of any increase is untested.…”

Section: Introductionmentioning

confidence: 99%

Analysis of tetraplegic reaching in their 3D workspace following posterior deltoid-triceps tendon transfer

et al. 2010

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Study design: Cross-sectional study. Objectives: To quantify three-dimensional (3D) reachable workspace in different groups of tetraplegic participants and to assess their reaching performance within this workspace. Setting: Northwest Regional Spinal Injuries Centre, UK. Methods: The 3D reachable workspace of three groups of tetraplegics (NON-OP, operated group (OP) and tetraplegic control group (CON Tetraplegic ) with varying levels of triceps function together with a healthy control group (CON Healthy )) was defined by reaching to five target positions (anterior, medial, lateral, superior and inferior) located on the periphery of their workspace. Joint angles and inter-joint coordination were analysed after a 3D reconstruction of the thorax, humerus and forearm. The performance related variables of movement time, peak velocity, time-to-peak velocity and curvature index were also examined. Results: The reachable volumes covered were consistent with the level of triceps function as CON Healthy covered a significantly greater volume than the tetraplegic groups and in turn the OP covered a larger workspace volume than NON-OP. The reduced workspace of tetraplegics was identified as being due to restrictions in workspace above shoulder height and across the body. Coordination data identified some differences in movement patterns but when reaching to targets on the workspace there were no significant differences between the OP and NON-OP groups. Conclusion: This study provided a detailed assessment of reachable workspace and target reaching. Tetraplegic participants found the superior and medial parts of the workspace were the most challenging directions. Standardised biomechanical analysis of tetraplegic upper-limb function is required for objective assessment.

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Section: Introductionmentioning

confidence: 99%

Analysis of tetraplegic reaching in their 3D workspace following posterior deltoid-triceps tendon transfer

et al. 2010

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“…The movement of the shoulder is determined by several joints of the shoulder complex, but we consider only movement of the spherical glenohumeral (GH) joint at the shoulder: the range of movement of the other joints is limited, and hence can be considered part of torso movement. References [41] and [43] also ignore the shoulder complex to determine interrelation of joints when calculating the workspace of the human arm; these models are identical apart from the orientation of the first joint axis (a similar model is used by [21] with yet another first joint axis orientation). [29], [41], and [21].…”

Section: A 4-degree-of-freedom Modelmentioning

confidence: 99%

“…Among other studies, [41] disregards hand and wrist movement, and rotation along the forearm axis. As these movements do not greatly affect the occupancy, we also remove these joints to reduce complexity; this leaves us with a 4-DOF model.…”

Section: A 4-degree-of-freedom Modelmentioning

confidence: 99%

Overapproximative Human Arm Occupancy Prediction for Collision Avoidance

Pereira

Althoff

2018

IEEE Trans. Automat. Sci. Eng.

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Abstract-Predicting the occupancy of a human in real time is of great interest in human-robot coexistence for obtaining regions that a robot should avoid in safe motion planning. The human body is composed of joints and links, suiting approximation by a kinematic chain, but the control strategy of the human is completely unknown, meaning the potential occupancy grows very fast and it is difficult to compute tightly in real time. As such, most previous work considers only specific, known, or probable movements, and usually does not account for a range of human dimensions. Focusing on the human arm, we analyze archetypal movements performed by test subjects to create a dynamic model. Motion-capture data of subjects are fitted, for modeling purposes, to two abstractions: a 4-degree of freedom (DOF) model and a 3-DOF model, to obtain dynamic parameters. We validate our approach on movements from a publicly available database. The prediction is shown to be computationally fast, and reachable sets of the abstraction are shown to enclose all possible future occupancies of the arm for different subjects, tightly but overapproximatively. The 3-DOF model has advantages over the 4-DOF in terms of speed, though the 4-DOF model is tighter at smaller time horizons. Such an overapproximative representation is intended for certifiable safety-guaranteed collision avoidance algorithms for robots.Note to Practitioners-Motivated by the need to keep humans safe when working alongside robots, our earlier work proposes a method of trajectory planning where the robot certifies each movement as safe before it performs it. For this to prove that unsafe collisions cannot occur, an overapproximative prediction of the human is needed, meaning that no possible future position of the human is outside the predicted region, or reachable occupancy. However, making this prediction both small enough (so that it does not include unreachable regions) and fast enough for real-time use is not straightforward. We find the limits of human motion by asking a range of test subjects to perform movements as fast as possible. We calculate the reachable occupancies based on these limits and show that our predictions are indeed overapproximative, fast, and not wasteful of volume. One can then use the aforementioned approach to guarantee safety; future challenges are reliably sensing the human's pose and implementing our approach on an industrial robot.

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“…These are intended to allow the reachable workspace of patients with upper limb impairments to be calculated. In this work we consider the person wearing the exoskeleton as not having an impairment and hence use the healthy values shown in Table 1 taken from [11] and adapted for the model [12]. Representation of the humerus ROM is made by generating a large set of orientations the humerus can reach in the workspace.…”

Section: Human Shoulder Range Of Motion (Rom)mentioning

confidence: 99%

“…When designing the shoulder mechanism a common approach is to focus on the location of the singularity and manually position it outside or at the edge of the desired workspace to maximise the usable range of motion [9,16,1,2]. In this work we design a shoulder exoskeleton using an optimisation process that incorporates a biomechanical model of the human arm [12,11]. With the human shoulder ROM defined by the biomechanical model, the design parameters of an exoskeleton are optimised using a genetic algorithm to maximise its ROM towards that of the human, whilst accounting for singularity and collisions.…”

Section: Introductionmentioning

confidence: 99%

Human Biomechanical Model Based Optimal Design of Assistive Shoulder Exoskeleton

Carmichael

Liu

2015

Springer Tracts in Advanced Robotics

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Robotic exoskeletons are being developed to assist humans in tasks such as robotic rehabilitation, assistive living, industrial and other service applications. Exoskeletons for the upper limb are required to encompass the shoulder whilst achieving a range of motion so as to not impede the wearer, avoid collisions with the wearer, and avoid kinematic singularities during operation. However this is particularly challenging due to the large range of motion of the human shoulder. In this paper a biomechanical model based optimisation is applied to the design of a shoulder exoskeleton with the objective of maximising shoulder range of motion. A biomechanical model defines the healthy range of motion of the human shoulder. A genetic algorithm maximises the range of motion of the exoskeleton towards that of the human, whilst taking into account collisions and kinematic singularities. It is shown how the optimisation can increase the exoskeleton range of motion towards that equivalent of the human, or towards a subset of human range of motion relevant to specific applications.

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A kinematic model of the shoulder complex to evaluate the arm-reachable workspace

Cited by 79 publications

References 9 publications

Analysis of tetraplegic reaching in their 3D workspace following posterior deltoid-triceps tendon transfer

Analysis of tetraplegic reaching in their 3D workspace following posterior deltoid-triceps tendon transfer

Overapproximative Human Arm Occupancy Prediction for Collision Avoidance

Human Biomechanical Model Based Optimal Design of Assistive Shoulder Exoskeleton

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