Modelling and Simulation of a Manipulator with Stable Viscoelastic Grasping Incorporating Friction

Design, dynamics and control of a humanoid robotic hand based on anthropological dimensions, with joint friction, is modelled, simulated and analysed in this paper by using computer aided design and multibody dynamic simulation. Combined joint friction model is incorporated in the joints. Experimental values of coefficient of friction of grease lubricated sliding contacts representative of manipulator joints are presented. Human fingers deform to the shape of the grasped object (enveloping grasp) at the area of interaction. A mass-spring-damper model of the grasp is developed. The interaction of the viscoelastic gripper of the arm with objects is analysed by using Bond Graph modelling method. Simulations were conducted for several material parameters. These results of the simulation are then used to develop a prototype of the proposed gripper. Bond graph model is experimentally validated by using the prototype. The gripper is used to successfully transport soft and fragile objects. This paper provides information on optimisation of friction and its inclusion in both dynamic modelling and simulation to enhance mechanical efficiency

사람 손 움직임을 반영한 부족구동 텐던구동 로봇 손의 디자인 및 제어

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2017. 2. 이동준.We propose a novel design framework for the under-actuated tendon-driven (UATD) robotic finger. In this study, we decompose the system equation based on its stiffness to separate the actuated space and the un-actuated space. The actuated space appears during the free motion when no disturbance is exerted, whereas the un-actuated space is observed when there is contact. We measure the index finger joint angles and contact force during both the free motion and the contact, and search for the efficient design parameters (stiffness, active tendon routing, initial configuration) to mimic the human finger motion. We formulate the optimization problem to find those parameters and we consider the system constraints, s.t. finger thickness and unilaterality of tendon-driven mechanism, simultaneously. We also design a simple PD-based control to track the desired joint angle, and we show the simulation results.1 Introduction 1 2 Preliminary 4 2.1 Modeling of UATD Robotic Finger 4 2.2 Design Objective 8 3 Design of UTAD Robotic Finger 10 3.1 Stiness Decomposition 10 3.2 Actuated Space Search via Motion Analysis 14 3.2.1 Experiments for Joint Angles 14 3.2.2 PCA for the Joint Space 17 3.3 Stiness Design via Un-Actauted Deformation Minimization 20 3.3.1 Experimental Settings 20 3.3.2 Minimization of the Un-Actuated Deformation 22 3.3.3 Determination of Stiness 24 3.4 Active Tendon Routing and Initial Joint Angles Design via Motion Analysis 25 4 Control and Simulation Results 30 4.1 Control 30 4.2 Simulation Results 32 5 Conclusion and Future Work 35 5.1 Conclusion 35 5.2 Future Work 36 Bibliography 37 요약 42Maste

Innovative robot hand designs of reduced complexity for dexterous manipulation

This thesis investigates the mechanical design of robot hands to sensibly reduce the system complexity in terms of the number of actuators and sensors, and control needs for performing grasping and in-hand manipulations of unknown objects. Human hands are known to be the most complex, versatile, dexterous manipulators in nature, from being able to operate sophisticated surgery to carry out a wide variety of daily activity tasks (e.g. preparing food, changing cloths, playing instruments, to name some). However, the understanding of why human hands can perform such fascinating tasks still eludes complete comprehension. Since at least the end of the sixteenth century, scientists and engineers have tried to match the sensory and motor functions of the human hand. As a result, many contemporary humanoid and anthropomorphic robot hands have been developed to closely replicate the appearance and dexterity of human hands, in many cases using sophisticated designs that integrate multiple sensors and actuators---which make them prone to error and difficult to operate and control, particularly under uncertainty. In recent years, several simplification approaches and solutions have been proposed to develop more effective and reliable dexterous robot hands. These techniques, which have been based on using underactuated mechanical designs, kinematic synergies, or compliant materials, to name some, have opened up new ways to integrate hardware enhancements to facilitate grasping and dexterous manipulation control and improve reliability and robustness. Following this line of thought, this thesis studies four robot hand hardware aspects for enhancing grasping and manipulation, with a particular focus on dexterous in-hand manipulation. Namely: i) the use of passive soft fingertips; ii) the use of rigid and soft active surfaces in robot fingers; iii) the use of robot hand topologies to create particular in-hand manipulation trajectories; and iv) the decoupling of grasping and in-hand manipulation by introducing a reconfigurable palm. In summary, the findings from this thesis provide important notions for understanding the significance of mechanical and hardware elements in the performance and control of human manipulation. These findings show great potential in developing robust, easily programmable, and economically viable robot hands capable of performing dexterous manipulations under uncertainty, while exhibiting a valuable subset of functions of the human hand.Open Acces

Metodología de diseño de manos robóticas basada en los estados de su sistema accionador

La mano humana es una de las herramientas más asombrosas de la naturaleza, tanto que no ha podido ser superada en ningún aspecto hasta el momento. Siendo el principal medio por el cual se ha creado y construido, directa o indirectamente, todo lo artificial que actualmente nos rodea, es natural pensar de que gran parte de la comunidad científica relacionada con la robótica dedique grandes esfuerzos por imitarla. En la actualidad se puede realizar un extenso catálogo de manos robóticas desarrolladas y todas buscan resolver un determinado comportamiento de la mano humana, aún así, éstas se pueden dividir en tres grupos bien definidos: las pinzas robóticas, las cuales se caracterizan por su aplicación industrial en tareas de agarre firme de elementos específicos y por su robustez, precio y vida útil; por otro lado, están las manos robóticas subactuadas en las que se buscan mecanismos cada vez más complejos que hagan disminuir la cantidad de actuadores y la complejidad de su sistema de control a favor de mejorar la funcionalidad de las pinzas robóticas en lo que se refiere a extender su capacidad de agarre a objetos con formas y tamaños cada vez más diferentes; y finalmente encontramos las demás manos robóticas en las que su objetivo es la experimentación de un determinado comportamiento de la mano humana más centrada en las tareas de manipulación. Esta tesis propone una metodología de diseño de manos robóticas desde un punto de vista particular, que es el de los estados que puede ofrecer su sistema de accionamiento, teniendo en cuenta la capacidad de combinarlos y hacerlos independientes. Los elementos móviles que componen una mano robótica son accionados por un actuador o conjunto de actuadores. El sistema accionador es el órgano principal que da vida a un determinado sistema robótico como una mano robótica, por lo tanto es preciso identificar la capacidad que tiene el mismo de hacer que ese movimiento pueda generar tareas cada vez más complejas. La forma de identificar esta capacidad se resume en los estados y la calidad de los mismos que el sistema accionador puede ofrecer. Esta metodología de diseño se basa fundamentalmente en este concepto y que si bien en este trabajo es aplicado a manos robóticas, puede ser extendido a cualquier sistema robótico que disponga de un sistema accionador y de esta forma optimizar sus recursos no sólo a nivel funcional, sino también en el ahorro de energía. En el transcurso de este trabajo se han diseñado dos manos robóticas con esta metodología y se ha realizado un ensayo de viabilidad técnica de un actuador capaz de ofrecer un número finito de estados mayor a los tres que ofrece actualmente cualquier actuador. Estos diseños han demostrado que este tipo de metodología puede ofrecer una alternativa para la optimización del sistema accionador de una mano robótica. Por otro lado, la misma también puede ser aplicada a cualquier tipo de mano robótica y para cualquier aplicación y servir como una herramienta útil para el análisis del diseño de las manos robóticas actuales y buscar puntos de optimización para futuros desarrollos

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