A novel design process of low cost 3D printed ambidextrous finger designed for an ambidextrous robotic hand

This paper presents the novel mechanical design of an ambidextrous finger specifically designed for an ambidextrous anthropomorphic robotic hand actuated by pneumatic artificial muscles. The ambidextrous nature of design allows fingers to perform both left and right hand movements. The aim of our design is to reduce the number of actuators, increase the range of movements with best possible range ideally greater than a common human finger. Four prototypes are discussed in this paper; first prototype is focused on the choice of material and to consider the possible ways to reduce friction. Second prototype is designed to investigate the tendons routing configurations. Aim of third and fourth prototype is to improve the overall performance and to maximize the grasping force. Finally, a unified design (Final design) is presented in great detail. Comparison of all prototypes is done from different angles to evaluate the best design. The kinematic features of intermediate mode have been analysed to optimize both the flexibility and the robustness of the system, as well as to minimize the number of pneumatic muscles. The final design of an ambidextrous finger has developed, tested and 3D printed

Mechanical engineering challenges in humanoid robotics

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 36-39).Humanoid robots are artificial constructs designed to emulate the human body in form and function. They are a unique class of robots whose anthropomorphic nature renders them particularly well-suited to interact with humans in a world designed for humans. The present work examines a subset of the plethora of engineering challenges that face modem developers of humanoid robots, with a focus on challenges that fall within the domain of mechanical engineering. The challenge of emulating human bipedal locomotion on a robotic platform is reviewed in the context of the evolutionary origins of human bipedalism and the biomechanics of walking and running. Precise joint angle control bipedal robots and passive-dynamic walkers, the two most prominent classes of modem bipedal robots, are found to have their own strengths and shortcomings. An integration of the strengths from both classes is likely to characterize the next generation of humanoid robots. The challenge of replicating human arm and hand dexterity with a robotic system is reviewed in the context of the evolutionary origins and kinematic structure of human forelimbs. Form-focused design and function-focused design, two distinct approaches to the design of modem robotic arms and hands, are found to have their own strengths and shortcomings. An integration of the strengths from both approaches is likely to characterize the next generation of humanoid robots.by Peter Guang Yi Lu.S.B

On Neuromechanical Approaches for the Study of Biological Grasp and Manipulation

Biological and robotic grasp and manipulation are undeniably similar at the level of mechanical task performance. However, their underlying fundamental biological vs. engineering mechanisms are, by definition, dramatically different and can even be antithetical. Even our approach to each is diametrically opposite: inductive science for the study of biological systems vs. engineering synthesis for the design and construction of robotic systems. The past 20 years have seen several conceptual advances in both fields and the quest to unify them. Chief among them is the reluctant recognition that their underlying fundamental mechanisms may actually share limited common ground, while exhibiting many fundamental differences. This recognition is particularly liberating because it allows us to resolve and move beyond multiple paradoxes and contradictions that arose from the initial reasonable assumption of a large common ground. Here, we begin by introducing the perspective of neuromechanics, which emphasizes that real-world behavior emerges from the intimate interactions among the physical structure of the system, the mechanical requirements of a task, the feasible neural control actions to produce it, and the ability of the neuromuscular system to adapt through interactions with the environment. This allows us to articulate a succinct overview of a few salient conceptual paradoxes and contradictions regarding under-determined vs. over-determined mechanics, under- vs. over-actuated control, prescribed vs. emergent function, learning vs. implementation vs. adaptation, prescriptive vs. descriptive synergies, and optimal vs. habitual performance. We conclude by presenting open questions and suggesting directions for future research. We hope this frank assessment of the state-of-the-art will encourage and guide these communities to continue to interact and make progress in these important areas

Design and Control of the McKibben Artificial Muscles Actuated Humanoid Manipulator

The McKibben Pneumatic Artificial Muscles (PAMs) are expected to endow the advanced robots with the ability of coexisting and cooperating with humans. However, the application of PAMs is still severely hindered by some critical issues. Focusing on the bionic design issue, this chapter in detail presents the design of a 7-degree-of-freedom (DOF) human-arm-like manipulator. It takes the antagonized PAMs and Bowden cables to mimic the muscle-tendon-ligament structure of human arm by elaborately configuring the DOFs and flexibly deploying the routing of Bowden cables; as a result, the DOFs of the analog shoulder, elbow, and wrist of the robotic arm intersect at a point respectively and the motion of these DOFs is independent from each other for convenience of human-like motion. The model imprecision caused by the strong nonlinearity is universally acknowledged as a main drawback of the PAM systems. Focusing on this issue, this chapter views the model imprecision as an internal disturbance, and presents an approach that observe these disturbances with extended-state-observer (ESO) and compensate them with full-order-sliding-mode-controller (fSMC), via experiments validated the human-like motion performance with expected robustness and tracking accuracy. Finally, some variants of PAMs for remedying the drawbacks of the PAM systems are discussed

A McKibben muscle arm learning equilibrium postures

In designing artificial systems for studying motor control in humans and other organisms a key point to consider is the complexity reached by brain and body in their developmental stages. An artificial system whose brain and body complexity is shaped according to developmental stages might allow understanding weather, for example, newborn infants, infants, and adults use different neural mechanisms to cope with the same motor control problems. This article proposes an artificial system which aims at becoming a tool to study this type of problems. The system has a brain and body endowed with a set of minimal bio-mimetic features: (a) neural maps activated by receptive fields; (b) connections plasticity changed by Hebbian rule; (c) robotic arm actuated by a McKibben muscle. The arm autonomously learns to reach specific positions in space under the effect of gravity and for different load conditions. The results suggest that a fast and incremental goalaction mapping formation could constitute the computational mechanism underlying the neural growth and plasticity of an early developed brain at the onset of reaching. The same mechanism also allows a first approximate solution for load compensation avoiding the use of more sophisticated internal models (developed in further brain and body developmental stages). This paper aims to be a preliminary study on the feasibility of this approach

Design of a Knee Exoskeleton actuated with Artificial Muscles of SMA

This project presents the preliminary design of a powered exoskeleton for the knee joint, build upon the structural framework of DonJoy’s X-Act Rom Lite - Knee Brace. The device allows exclusively one degree of freedom, intended for the flexion and extension of the lower limb. The actuation mechanism is based on artificial muscles of Nitinol fibers, which are a type of Shape Memory Alloys (SMA). These wires contract 4% of its original length as the temperature rises due to the Joule Effect, when connected to a power supply. Thanks to this phenomenon, the proposed robotic orthosis presents portability, lightness and noiseless performance, in comparison to similar products. The main role of these instruments is to conduct medical rehabilitation therapy for those patients who have suffered from neurological diseases, musculoskeletal lesions or spinal cord injuries. Consequently, the wearer might recover -partially or fully- the movement on the joint. The results from several trials were obtained after mimicking real rehabilitation positions -like sitting, standing or lying down- and are analyzed thoroughly in this thesis. All in all, this prototype proves how the SMA actuators are a viable alternative to create lower extremity robotic devices for rehabilitation.Ingeniería Biomédic