Augmentation de performance des doigts sous-actionnés par actionnement multiple

RÉSUMÉ Les préhenseurs font partie des éléments critiques en robotique, notamment lorsqu’ils sont amenés à saisir des objets de formes et de grandeurs différentes. L’utilisation typique d’un actionneur pour chaque degré de liberté (DDL) constitue un système complexe nécessitant généralement l’utilisation de plusieurs capteurs et d’algorithmes de contrôle évolués. Les concepts sous-actionnés, pour leur part, ne nécessitent généralement pas ces éléments. Ils suscitent donc un intérêt grandissant et font l’objet de plus en plus d’études, le coût et le poids devenant des enjeux inévitables. La plupart des mécanismes sous-actionnés n’utilisent pas plus d’un actionneur agissant sur les mêmes DDL. Pour les doigts sous-actionnés, sujet de ce mémoire, l’utilisation d’un seul actionneur peut limiter les performances. L’objectif de la présente étude est de quantifier les avantages de l’actionnement multiple, c’est-à-dire l’utilisation de plusieurs actionneurs. Deux cas sont étudiés. Le premier porte sur l’amélioration des performances du point de vue de la saisie d’objets. Le deuxième porte sur le contrôle de la trajectoire de fermeture, c’est-à-dire le mouvement libre du doigt sans qu’il y ait contact avec un objet. Dans le premier cas, l’amélioration des performances de la prise englobante, c’est-à-dire enveloppant l’objet en maximisant le nombre de contacts, est évaluée pour différentes combinaisons d’actionneurs, après une optimisation de la géométrie pour chacune d’entre elles. Deux architectures sont étudiées, une pour laquelle un maximum de trois couples d’actionnement sont distribués à l’intérieur du mécanisme, et l’autre pouvant accueillir deux actionneurs dans la paume. Pour la première, une amélioration marquée de la performance est observée, alors que pour la deuxième, la différence est plutôt modeste. Dans le deuxième cas, l’architecture comportant deux actionneurs dans la paume est optimisée pour obtenir deux trajectoires de fermeture différentes. L’actionnement du doigt par un des actionneurs occasionne une trajectoire analogue à une prise englobante alors que l’utilisation du second en occasionne une pour laquelle la phalange distale demeure perpendiculaire à la paume. Un prototype de ce doigt ayant le comportement escompté est présenté. À la lumière de cette étude, il est clair qu’il y a avantage à utiliser plusieurs actionneurs sur un doigt sous-actionné, que ce soit pour améliorer les performances de la saisie d’objets ou pour permettre le contrôle de la trajectoire de fermeture.----------ABSTRACT Grippers are one of the critical elements in robotics, especially when they get to grasp differently shaped and sized objects. Typical use of one actuator per degree of freedom (DOF) leads to complex mechanisms generally needing many sensors and advanced control algorithms. However in most cases, underactuated designs do not need those components. Therefore, underactuated grippers are the focus of a growing number of works as cost and weight become inescapable issues. Most underactuated mechanisms use no more than one actuator for a set of DOF. As for underactuated fingers, topic of this work, using a single actuator can limit their performance. The main objective of this work is to quantify the advantages of multiple drive actuation, i.e., using several actuators. Two cases are studied. The first focuses on grasp performance augmentation. The second one is about motion control. In the first study case, grasp performance augmentation is assessed for various combinations of actuators, geometry being optimized for each one. Two architectures are studied, one for which a maximum of three torques inputs are distributed throughout the mechanism, and another able to accommodate two actuators in the palm. For the first one, a significant performance amelioration is observed, while for the second one, the difference is modest. In the second study case, the architecture using two actuators in the palm is optimized in order to obtain two distinct closing motions. Driving the finger with one actuator leads to a enveloping grasp like motion, while using the second one leads to a pinch grasp preshaping, i.e., a closing motion for which the distal phalanx remains perpendicular to the palm. A prototype showing the expected behaviour is presented. In the light of this study, it is clear that using several actuators on an underactuated finger is an advantage, whether it be for grasp performance augmentation or to allow motion control

The role of morphology of the thumb in anthropomorphic grasping : a review

The unique musculoskeletal structure of the human hand brings in wider dexterous capabilities to grasp and manipulate a repertoire of objects than the non-human primates. It has been widely accepted that the orientation and the position of the thumb plays an important role in this characteristic behavior. There have been numerous attempts to develop anthropomorphic robotic hands with varying levels of success. Nevertheless, manipulation ability in those hands is to be ameliorated even though they can grasp objects successfully. An appropriate model of the thumb is important to manipulate the objects against the fingers and to maintain the stability. Modeling these complex interactions about the mechanical axes of the joints and how to incorporate these joints in robotic thumbs is a challenging task. This article presents a review of the biomechanics of the human thumb and the robotic thumb designs to identify opportunities for future anthropomorphic robotic hands

Anthropomorphic robot finger with multi-point tactile sensation

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 84-95).The goal of this research is to develop the prototype of a tactile sensing platform for anthropomorphic manipulation research. We investigate this problem through the fabrication and simple control of a planar 2-DOF robotic finger inspired by anatomic consistency, self-containment, and adaptability. The robot is equipped with a tactile sensor array based on optical transducer technology whereby localized changes in light intensity within an illuminated foam substrate correspond to the distribution and magnitude of forces applied to the sensor surface plane [58]. The integration of tactile perception is a key component in realizing robotic systems which organically interact with the world. Such natural behavior is characterized by compliant performance that can initiate internal, and respond to external, force application in a dynamic environment. However, most of the current manipulators that support some form of haptic feedback, either solely derive proprioceptive sensation or only limit tactile sensors to the mechanical fingertips. These constraints are due to the technological challenges involved in high resolution, multi-point tactile perception. In this work, however, we take the opposite approach, emphasizing the role of full-finger tactile feedback in the refinement of manual capabilities. To this end, we propose and implement a control framework for sensorimotor coordination analogous to infant-level grasping and fixturing reflexes. This thesis details the mechanisms used to achieve these sensory, actuation, and control objectives, along with the design philosophies and biological influences behind them. The results of behavioral experiments with the tactilely-modulated control scheme are also described. The hope is to integrate the modular finger into an engineered analog of the human hand with a complete haptic system.by Jessica Lauren Banks.S.M

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 257

This bibliography lists 331 reports, articles and other documents introduced into the NASA scientific and technical information system in March 1984

Parametric mechanical design and optimisation of the Canterbury Hand.

As part of worldwide research humanoid robots have been developed for household, industrial and exploratory applications. If such robots are to interact with people and human created environments they will require human-like hands. The objective of this thesis was the parametric design and optimisation of a dexterous, and anthropomorphic robotic end effector. Known as the ‘Canterbury Hand’ it has 11 degree of freedoms with four fingers and a thumb. The hand has applications for dexterous teleoperation and object manipulation in industrial, hazardous or uncertain environments such as orbital robotics. The human hand was analysed so that the Canterbury Hand could copy its motions, appearance and grasp types. An analysis of the current literature on experimental prosthetic and robotic hands was also carried out. A disadvantage of many of these hand designs was that they were remotely powered using large, heavy actuator packs. The advantage of the Canterbury Hand is that it has been designed to hold the motors, wires, and circuit boards entirely within itself; although a belt carried battery pack is required. The hand was modelled using a parametric 3D computer aided design (CAD) program. Two different configurations of the hand were created in the model. One configuration, as a dexterous robot hand, used Ø13mm 3 Watt DC motors, while the other used Ø10mm, 0.5 Watt DC motors (although this hand is still slightly too large for a general prosthesis). The parts within the hand were modelled to permit changes to the geometry. This was necessary for the optimisation process. The bearing geometry of the finger and thumb linkages, as well as the thumb rotation axis was optimised for anthropomorphic motion, appearance and increased force output. A design table within a spreadsheet was created to interact with the CAD models of the hand to quickly implement the optimised geometry. The work reported in this thesis has shown the possibilities for parametric design and optimisation of an anthropomorphic, dexterous robotic hand

Parametric mechanical design and optimisation of the Canterbury Hand.

As part of worldwide research humanoid robots have been developed for household, industrial and exploratory applications. If such robots are to interact with people and human created environments they will require human-like hands. The objective of this thesis was the parametric design and optimisation of a dexterous, and anthropomorphic robotic end effector. Known as the ‘Canterbury Hand’ it has 11 degree of freedoms with four fingers and a thumb. The hand has applications for dexterous teleoperation and object manipulation in industrial, hazardous or uncertain environments such as orbital robotics. The human hand was analysed so that the Canterbury Hand could copy its motions, appearance and grasp types. An analysis of the current literature on experimental prosthetic and robotic hands was also carried out. A disadvantage of many of these hand designs was that they were remotely powered using large, heavy actuator packs. The advantage of the Canterbury Hand is that it has been designed to hold the motors, wires, and circuit boards entirely within itself; although a belt carried battery pack is required. The hand was modelled using a parametric 3D computer aided design (CAD) program. Two different configurations of the hand were created in the model. One configuration, as a dexterous robot hand, used Ø13mm 3 Watt DC motors, while the other used Ø10mm, 0.5 Watt DC motors (although this hand is still slightly too large for a general prosthesis). The parts within the hand were modelled to permit changes to the geometry. This was necessary for the optimisation process. The bearing geometry of the finger and thumb linkages, as well as the thumb rotation axis was optimised for anthropomorphic motion, appearance and increased force output. A design table within a spreadsheet was created to interact with the CAD models of the hand to quickly implement the optimised geometry. The work reported in this thesis has shown the possibilities for parametric design and optimisation of an anthropomorphic, dexterous robotic hand

Advancing Medical Technology for Motor Impairment Rehabilitation: Tools, Protocols, and Devices

Excellent motor control skills are necessary to live a high-quality life. Activities such as walking, getting dressed, and feeding yourself may seem mundane, but injuries to the neuromuscular system can render these tasks difficult or even impossible to accomplish without assistance. Statistics indicate that well over 100 million people are affected by diseases or injuries, such as stroke, Parkinson’s Disease, Multiple Sclerosis, Cerebral Palsy, peripheral nerve injury, spinal cord injury, and amputation, that negatively impact their motor abilities. This wide array of injuries presents a challenge to the medical field as optimal treatment paradigms are often difficult to implement due to a lack of availability of appropriate assessment tools, the inability for people to access the appropriate medical centers for treatment, or altogether gaps in technology for treating the underlying impairments causing the disability. Addressing each of these challenges will improve the treatment of movement impairments, provide more customized and continuous treatment to a larger number of patients, and advance rehabilitative and assistive device technology. In my research, the key approach was to develop tools to assess and treat upper extremity movement impairment. In Chapter 2.1, I challenged a common biomechanical[GV1] modeling technique of the forearm. Comparing joint torque values through inverse dynamics simulation between two modeling platforms, I discovered that representing the forearm as a single cylindrical body was unable to capture the inertial parameters of a physiological forearm which is made up of two segments, the radius and ulna. I split the forearm segment into a proximal and distal segment, with the rationale being that the inertial parameters of the proximal segment could be tuned to those of the ulna and the inertial parameters of the distal segment could be tuned to those of the radius. Results showed a marked increase in joint torque calculation accuracy for those degrees of freedom that are affected by the inertial parameters of the radius and ulna. In Chapter 2.2, an inverse kinematic upper extremity model was developed for joint angle calculations from experimental motion capture data, with the rationale being that this would create an easy-to-use tool for clinicians and researchers to process their data. The results show accurate angle calculations when compared to algebraic solutions. Together, these chapters provide easy-to-use models and tools for processing movement assessment data. In Chapter 3.1, I developed a protocol to collect high-quality movement data in a virtual reality task that is used to assess hand function as part of a Box and Block Test. The goal of this chapter is to suggest a method to not only collect quality data in a research setting but can also be adapted for telehealth and at home movement assessment and rehabilitation. Results indicate that the data collected in this protocol are good and the virtual nature of this approach can make it a useful tool for continuous, data driven care in clinic or at home. In Chapter 3.2 I developed a high-density electromyography device for collecting motor unit action potentials of the arm. Traditional surface electromyography is limited by its ability to obtain signals from deep muscles and can also be time consuming to selectively place over appropriate muscles. With this high-density approach, muscle coverage is increased, placement time is decreased, and deep muscle activity can potentially be collected due to the high-density nature of the device[GV2] . Furthermore, the high-density electromyography device is built as a precursor to a high-density electromyography-electrical stimulation device for functional electrical stimulation. The customizable nature of the prototype in Chapter 3.2 allows for the implementation both recording and stimulating electrodes. Furthermore, signal results show that the electromyography data obtained from the device are of high quality and are correlated with gold standard surface electromyography sensors. One key factor in a device that can record and then stimulate based on the information from the recorded signals is an accurate movement intent decoder. High-quality movement decoders have been designed by closed-loop device controllers in the past, but they still struggle when the user interacts with objects of varying weight due to underlying alterations in muscle signals. In Chapter 4, I investigate this phenomenon by administering an experiment where participants perform a Box and Block Task with objects of 3 different weights, 0 kg, 0.02 kg, and 0.1 kg. Electromyography signals of the participants right arm were collected and co-contraction levels between antagonistic muscles were analyzed to uncover alterations in muscle forces and joint dynamics. Results indicated contraction differences between the conditions and also between movement stages (contraction levels before grabbing the block vs after touching the block) for each condition. This work builds a foundation for incorporating object weight estimates into closed-loop electromyography device movement decoders. Overall, we believe the chapters in this thesis provide a basis for increasing availability to movement assessment tools, increasing access to effective movement assessment and rehabilitation, and advance the medical device and technology field

Modelling and analysis of hand motion in everyday activities with application to prosthetic hand technology

Upper-limb prostheses are either too expensive for many consumers or exhibit a greatly simplified choice of actions, this research aims to enable an improvement in the quality of life for recipients of these devices. Previous attempts at determining the hand shapes performed during activities of daily living (ADL) provide a limited range of tasks studied and data recorded. To avoid these limitations, motion capture systems and machine learning techniques have been utilised throughout this study. A portable motion capture system created, utilising a Leap Motion controller (LMC), has captured natural hand motions during modern ADL. Furthering the use of these data, a method applying optimisation techniques alongside a musculoskeletal model of the hand is proposed for predicting muscle excitations from kinematic data. The LMC was also employed in a device (AirGo) created to measure joint angles, aiming to provide an improvement to joint angle measurements in hand clinics. Hand movements for 22 participants were recorded during ADL over 111 hours and 20 minutes - providing a taxonomy of 40 and 24 hand shapes for the left and right hands, respectively. The predicted muscle excitations produced joint angles with an average correlation of 0.58 to those of the desired hand shapes. AirGo has been successfully employed within a hand therapy clinic to measure digit angles of 11 patients. A taxonomy of the hand shapes used in modern ADL is presented, highlighting the hand shapes currently more appropriate to consider during upper-limb prostheses development. A method for predicting the muscle excitations of the hand from kinematic data is introduced, implemented with data collected during ADL. AirGo offered improved repeatability over traditional devices used for such measurements with greater ease of use

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 267, January 1985

This publication is a cumulative index to the abstracts contained in the Supplements 255 through 266 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes seven indexes--subject, personal author, corporate source, foreign technology, contract number, report number, and accession number