Modeling the Frictional Interaction in the Tendon-Pulley System of the Human Finger for Use in Robotics

Dermitzakis, Konstantinos; Morales, Marco Roberto; Schweizer, Andreas

doi:10.1162/artl_a_00087

Cited by 7 publications

(8 citation statements)

References 46 publications

(58 reference statements)

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“…The modeling of the robot interaction with the environment, e.g. friction, use of different friction mechanisms, is difficult [44]. It becomes even more difficult for variable, semi-structured or unstructured environments.…”

Section: Model-free Controlmentioning

confidence: 99%

Design and Locomotion Control of a Soft Robot Using Friction Manipulation and Motor–Tendon Actuation

et al. 2016

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Robots built from soft materials can alter their shape and size in a particular profile. This shape-changing ability could be extremely helpful for rescue robots and those operating in unknown terrains and environments. In changing shape, soft materials also store and release elastic energy, a feature that can be exploited for effective robot movement. However, design and control of these moving soft robots are non-trivial. The research presents design methodology for a 3D-printed, motortendon actuated soft robot capable of locomotion. The modular design of the robot facilitates rapid fabrication, deployment and repair. In addition to shape change, the robot uses friction manipulation mechanisms to effect locomotion. The motor-tendon actuators comprise of nylon tendons embedded inside the soft body structure along a given path with one end fixed on the body and the other attached to a motor. These actuators directly control the deformation of the soft body which influences the robot locomotion behavior. Static stress analysis is used as a tool for designing the shape of the paths of these tendons embedded inside the body. The research also presents a novel model-free learning-based control approach for soft robots which interact with the environment at discrete contact points. This approach involves discretization of factors dominating robot-environment interactions as states, learning of the results as robot transitions between these robot states and evaluation of desired periodic state control sequences optimizing a cost function corresponding to a locomotion task (rotation or translation). The clever discretization allows the framework to exist in robot's task space, hence, facilitating calculation of control sequences without modeling the actuator, body material or details of the friction mechanisms. The flexibility of the framework is experimentally explored by applying it to robots with different friction mechanisms and different shapes of tendon paths.

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Section: Model-free Controlmentioning

confidence: 99%

Design and Locomotion Control of a Soft Robot Using Friction Manipulation and Motor–Tendon Actuation

et al. 2016

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“…The additional segments are virtual and required to properly align the thumb axes under the DH-convention. The z-axis is axial to the thumb in its neutral position 1 . The x-axis is the axis of motion when the thumb joints are actuated in flexion or extension, with flexion causing a positive change in x, and the y-axis is the axis of motion under abduction or adduction, with an abduction of the thumb causing a positive change in y.…”

Section: B Kinematic Models Of the Human Thumbmentioning

confidence: 99%

“…The loss of an upper-limb, or part thereof, causes a sudden and dramatic reduction in the ability of the affected person to (1) perform certain Activities of Daily Living (ADLs), (2) sense their surroundings, and (3) causes a major change to their cosmetic appearance [1]. As such, many upperextremity amputees seek to compensate this loss by wearing a prosthesis.…”

Section: Introductionmentioning

confidence: 99%

Robotic thumb grasp-based range of motion optimisation

Dermitzakis¹,

Ioannides²,

Lin³

2013

2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

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Abstract-With the thumb serving an important role in the function of the human hand, improving robotic prosthetic thumb functionality will have a direct impact on the prosthesis itself. So far, no significant work exists that examines the ranges of motion a prosthetic thumb should exhibit; many myoelectric prostheses arbitrarily select them. We question this design practice as we expect a significant functional volume reduction for performing certain activities vs. the maximum obtainable workspace. To this end, we compare and contrast four anatomically-accurate thumb models. We quantify their angular ranges of motion by generating point clouds of endeffector positions, and by computing their alpha-shape bounded volumes. Examining the function of the thumb for several grasps, we identify a 76% reduction of the required workspace volume vis-a-vis the maximum volume of a "'generic"' human thumb.

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“…In order to describe the phenomenological behavior of the friction switch, we have used a frictional two-link, one joint, finger tendon-pulley model that has been show to correspond well with physiological data [19]. The frictional tendonpulley interaction is modeled using the capstan friction equation [20].…”

Section: Empirical Friction Switching Modelmentioning

confidence: 99%

Bio-inspired friction switches: Adaptive pulley systems

Dermitzakis¹,

Carbajal²

2013

2013 IEEE/RSJ International Conference on Intelligent Robots and Systems

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Frictional influences in tendon-driven robotic systems are generally unwanted, with efforts towards minimizing them where possible. In the human hand however, the tendon-pulley system is found to be frictional with a difference between high-loaded static post-eccentric and post-concentric force production of 9-12% of the total output force. This difference can be directly attributed to tendon-pulley friction. Exploiting this phenomenon for robotic and prosthetic applications we can achieve a reduction of actuator size, weight and consequently energy consumption. In this study, we present the design of a bio-inspired friction switch. The adaptive pulley is designed to minimize the influence of frictional forces under low and medium-loading conditions and maximize it under high-loading conditions. This is achieved with a dual-material system that consists of a high-friction silicone substrate and low-friction polished steel pins. The system, designed to switch its frictional properties between the low-loaded and high-loaded conditions, is described and its behavior experimentally validated with respect to the number and spacing of pins. The results validate its intended behavior, making it a viable choice for robotic tendondriven systems. * K. Dermitzakis is with the AILab, UZH, Switzerland dermitza@ifi.uzh.ch. J.P. Carbajal is with the ELIS Department, UGhent, Belgium juanpablo.carbajal@ugent.be.

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Modeling the Frictional Interaction in the Tendon-Pulley System of the Human Finger for Use in Robotics

Cited by 7 publications

References 46 publications

Design and Locomotion Control of a Soft Robot Using Friction Manipulation and Motor–Tendon Actuation

Design and Locomotion Control of a Soft Robot Using Friction Manipulation and Motor–Tendon Actuation

Robotic thumb grasp-based range of motion optimisation

Bio-inspired friction switches: Adaptive pulley systems

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