A Low-Cost Open-Source 3-D-Printed Three-Finger Gripper Platform for Research and Educational Purposes

Robotics research and education have gained significant attention in recent years due to increased development and commercial deployment of industrial and service robots. A majority of researchers working on robot grasping and object manipulation tend to utilize commercially available robot-manipulators equipped with various end effectors for experimental studies. However, commercially available robotic grippers are often expensive and are not easy to modify for specific purposes. To extend the choice of robotic end effectors freely available to researchers and educators, we present an open-source lowcost three-finger robotic gripper platform for research and educational purposes. The 3-D design model of the gripper is presented and manufactured with a minimal number of 3-D-printed components and an off-the-shelf servo actuator. An underactuated finger and gear train mechanism, with an overall gripper assembly design, are described in detail, followed by illustrations and a discussion of the gripper grasping performance and possible gripper platform modifications. The presented open-source gripper platform computer-aided design model is released for downloading on the authors research lab website(www.alaris.kz) and can be utilized by robotics researchers and educators as a design platform to build their own robotic end effector solutions for research and educational purposes

A low-cost open-source 3-D-printed three-finger gripper platform for research and educational purposes

Robotics research and education have gained significant attention in recent years due to increased development and commercial deployment of industrial and service robots. A majority of researchers working on robot grasping and object manipulation tend to utilize commercially available robot-manipulators equipped with various end effectors for experimental studies. However, commercially available robotic grippers are often expensive and are not easy to modify for specific purposes. To extend the choice of robotic end effectors freely available to researchers and educators, we present an open-source lowcost three-finger robotic gripper platform for research and educational purposes. The 3-D design model of the gripper is presented and manufactured with a minimal number of 3-D-printed components and an off-the-shelf servo actuator. An underactuated finger and gear train mechanism, with an overall gripper assembly design, are described in detail, followed by illustrations and a discussion of the gripper grasping performance and possible gripper platform modifications. The presented open-source gripper platform computer-aided design model is released for downloading on the authors research lab website(www.alaris.kz) and can be utilized by robotics researchers and educators as a design platform to build their own robotic end effector solutions for research and educational purposes

Advancing the Underactuated Grasping Capabilities of Single Actuator Prosthetic Hands

The last decade has seen significant advancements in upper limb prosthetics, specifically in the myoelectric control and powered prosthetic hand fields, leading to more active and social lifestyles for the upper limb amputee community. Notwithstanding the improvements in complexity and control of myoelectric prosthetic hands, grasping still remains one of the greatest challenges in robotics. Upper-limb amputees continue to prefer more antiquated body-powered or powered hook terminal devices that are favored for their control simplicity, lightweight and low cost; however, these devices are nominally unsightly and lack in grasp variety. The varying drawbacks of both complex myoelectric and simple body-powered devices have led to low adoption rates for all upper limb prostheses by amputees, which includes 35% pediatric and 23% adult rejection for complex devices and 45% pediatric and 26% adult rejection for body-powered devices [1]. My research focuses on progressing the grasping capabilities of prosthetic hands driven by simple control and a single motor, to combine the dexterous functionality of the more complex hands with the intuitive control of the more simplistic body-powered devices with the goal of helping upper limb amputees return to more active and social lifestyles. Optimization of a prosthetic hand driven by a single actuator requires the optimization of many facets of the hand. This includes optimization of the finger kinematics, underactuated mechanisms, geometry, materials and performance when completing activities of daily living. In my dissertation, I will present chapters dedicated to improving these subsystems of single actuator prosthetic hands to better replicate human hand function from simple control. First, I will present a framework created to optimize precision grasping – which is nominally unstable in underactuated configurations – from a single actuator. I will then present several novel mechanisms that allow a single actuator to map to higher degree of freedom motion and multiple commonly used grasp types. I will then discuss how fingerpad geometry and materials can better grasp acquisition and frictional properties within the hand while also providing a method of fabricating lightweight custom prostheses. Last, I will analyze the results of several human subject testing studies to evaluate the optimized hands performance on activities of daily living and compared to other commercially available prosthesis

Adaptive and reconfigurable robotic gripper hands with a meso-scale gripping range

Grippers and robotic hands are essential and important end-effectors of robotic manipulators. Developing a gripper hand that can grasp a large variety of objects precisely and stably is still an aspiration even though research in this area has been carried out for several decades. This thesis provides a development approach and a series of gripper hands which can bridge the gap between micro-gripper and macro-gripper by extending the gripping range to the mesoscopic scale (meso-scale). Reconfigurable topology and variable mobility of the design offer versatility and adaptability for the changing environment and demands. By investigating human grasping behaviours and the unique structures of human hand, a CFB-based finger joint for anthropomorphic finger is developed to mimic a human finger with a large grasping range. The centrodes of CFB mechanism are explored and a contact-aided CFB mechanism is developed to increase stiffness of finger joints. An integrated gripper structure comprising cross four-bar (CFB) and remote-centre-of-motion (RCM) mechanisms is developed to mimic key functionalities of human hand. Kinematics and kinetostatic analyses of the CFB mechanism for multimode gripping are conducted to achieve passive-adjusting motion. A novel RCM-based finger with angular, parallel and underactuated motion is invented. Kinematics and stable gripping analyses of the RCM-based multi-motion finger are also investigated. The integrated design with CFB and RCM mechanisms provides a novel concept of a multi-mode gripper that aims to tackle the challenge of changing over for various sizes of objects gripping in mesoscopic scale range. Based on the novel designed mechanisms and design philosophy, a class of gripper hands in terms of adaptive meso-grippers, power-precision grippers and reconfigurable hands are developed. The novel features of the gripper hands are one degree of freedom (DoF), self-adaptive, reconfigurable and multi-mode. Prototypes are manufactured by 3D printing and the grasping abilities are tested to verify the design approach.EPSR

On the development of a cybernetic prosthetic hand

The human hand is the end organ of the upper limb, which in humans serves the important function of prehension, as well as being an important organ for sensation and communication. It is a marvellous example of how a complex mechanism can be implemented, capable of realizing very complex and useful tasks using a very effective combination of mechanisms, sensing, actuation and control functions. In this thesis, the road towards the realization of a cybernetic hand has been presented. After a detailed analysis of the model, the human hand, a deep review of the state of the art of artificial hands has been carried out. In particular, the performance of prosthetic hands used in clinical practice has been compared with the research prototypes, both for prosthetic and for robotic applications. By following a biomechatronic approach, i.e. by comparing the characteristics of these hands with the natural model, the human hand, the limitations of current artificial devices will be put in evidence, thus outlining the design goals for a new cybernetic device. Three hand prototypes with a high number of degrees of freedom have been realized and tested: the first one uses microactuators embedded inside the structure of the fingers, and the second and third prototypes exploit the concept of microactuation in order to increase the dexterity of the hand while maintaining the simplicity for the control. In particular, a framework for the definition and realization of the closed-loop electromyographic control of these devices has been presented and implemented. The results were quite promising, putting in evidence that, in the future, there could be two different approaches for the realization of artificial devices. On one side there could be the EMG-controlled hands, with compliant fingers but only one active degree of freedom. On the other side, more performing artificial hands could be directly interfaced with the peripheral nervous system, thus establishing a bi-directional communication with the human brain

Quasi-dynamic analysis, design optimization, and evaluation of a two-finger underactuated hand

Underactuated hands are able to achieve shape adaptation to conformally grasp a wide variety of objects, while keeping low undesirable hand attributes such as weight, size, complexity and cost. The available analytical and simulation studies of planar underactuated hands normally assume quasi-static conditions and a fixed object. In the present paper, a new quasi-dynamic analysis of the grasping process in the horizontal plane by a planar, two-finger, four-joint underactuated hand is presented. The study considers object movement during the grasping process, and also contact friction with a surface that supports the object. An extensive and versatile simulation program, based on the analysis, is developed to investigate the effects of various parameters of hand and object on the grasping process. A prototype hand has been developed and the simulation results are validated experimentally. An extensive and detailed study and optimization exercise is carried out using the developed simulation tool. Specifically, the study concerns a manipulative grasping process that moves the object to the hand centerline during the process. Important new findings on the influence of link dimensions, link angular speeds, friction with the supporting surface, object mass and object size on the grasping performance of the hand in this scenario are presented. The results are used to establish new design guidelines for the hand. In particular, the results indicate that in the case where there is limited information on the size and precise initial location of the object to be grasped, the optimal hand design would involve inner to outer phalange size ratios of approximately 3:1, and inner phalange joints that are very close to each other.peer-reviewe

A Lightweight Universal Gripper with Low Activation Force for Aerial Grasping

Soft robotic grippers have numerous advantages that address challenges in dynamic aerial grasping. Typical multi-fingered soft grippers recently showcased for aerial grasping are highly dependent on the direction of the target object for successful grasping. This study pushes the boundaries of dynamic aerial grasping by developing an omnidirectional system for autonomous aerial manipulation. In particular, the paper investigates the design, fabrication, and experimental verification of a novel, highly integrated, modular, sensor-rich, universal jamming gripper specifically designed for aerial applications. Leveraging recent developments in particle jamming and soft granular materials, the presented gripper produces a substantial holding force while being very lightweight, energy-efficient and only requiring a low activation force. We show that the holding force can be improved by up to 50% by adding an additive to the membrane's silicone mixture. The experiments show that our lightweight gripper can develop up to 15N of holding force with an activation force as low as 2.5N, even without geometric interlocking. Finally, a pick and release task is performed under real-world conditions by mounting the gripper onto a multi-copter. The developed aerial grasping system features many useful properties, such as resilience and robustness to collisions and the inherent passive compliance which decouples the UAV from the environment.Comment: 21 pages, 19 figures; corrected affiliation

Space Exploration Robotic Systems - Orbital Manipulation Mechanisms

In the future, orbital space robots will assist humans in space by constructing and maintaining space modules and structures. Robotic manipulators will play essential roles in orbital operations. This work is devoted to the implemented designs of two different orbital manipulation mechanical grippers developed in collaboration with Thales Alenia Space Italy and NASA Jet Propulsion Laboratory – California Institute of Technology. The consensus to a study phase for an IXV (Intermediate eXperimental Vehicle) successor, a preoperational vehicle called SPACE RIDER (Space Rider Reusable Integrated Demonstrator for European Return), has been recently enlarged, as approved during last EU Ministerial Council. One of the main project task consists in developing SPACE RIDER to conduct on orbit servicing activity with no docking. SPACE RIDER would be provided with a robotic manipulator system (arm and gripper) able to transfer cargos, such as scientific payloads, from low Earth orbiting platforms to SPACE RIDER cargo bay. The platform is a part of a space tug designed to move small satellites and other payloads from Low Earth Orbit (LEO) to Geosynchronous Equatorial Orbit (GEO) and viceversa. The assumed housing cargo bay requirements in terms of volume (<100l) and mass (<50kg) combined with the required overall arm dimensions (4m length), and mass of the cargo (5-30kg) force to developing an innovative robotic manipulator with the task-oriented end effector. It results in a seven degree-of-freedom arm to ensure a high degree of dexterity and a dedicate end-effector designed to grasp the cargo interface. The gripper concept developed consists in a multi-finger hand able to lock both translational and rotational cargo degrees of freedom through an innovative underactuation strategy to limit its mass and volume. A configuration study on the cargo handle interface was performed together with some computer aided design models and multibody analysis of the whole system to prove its feasibility. Finally, the concept of system control architecture, the test report and the gripper structural analysis were defined. In order to be able to accurately analyze a sample of Martian soil and to determine if life was present on the red planet, a lot of mission concepts have been formulating to reach Mars and to bring back a terrain sample. NASA JPL has been studying such mission concepts for many years. This concept is made up of three intermediate mission accomplishments. Mars 2020 is the first mission envisioned to collect the terrain sample and to seal it in sample tubes. These sealed sample tubes could be inserted in a spherical envelope named Orbiting Sample (OS). A Mars Ascent Vehicle (MAV) is the notional rocket designed to bring this sample off Mars, and a Rendezvous Orbiting Capture System (ROCS) is the mission conceived to bring this sample back to Earth through the Earth Entry Vehicle (EEV). MOSTT is the technical work study to create new concepts able to capture and reorient an OS. This maneuver is particularly important because we do not know an OS incoming orientation and we need to be able to capture, to reorient it (2 rotational degrees of freedom), and to retain an OS (3 translational degrees of freedom and 2 rotational ones). Planetary protection requirements generate a need to enclose an OS in two shells and to seal it through a process called Break-The-Chain (BTC). Considering the EEV would return back to Earth, the tubes orientation and position have to be known in detail to prevent any possible damage during the Earth hard landing (acceleration of ∼1300g). Tests and analysis report that in order for the hermetic seals of the sample tubes to survive the impact, they should be located above an OS equator. Due to other system uncertainties an OS presents the potential requirement to be properly reoriented before being inserted inside the EEV. Planetary protection issues and landing safety are critical mission points and provide potential strict requirements to MOSTT system configuration. This task deals with the concept, design, and testbed realization of an innovative electro-mechanical system to reorient an OS consistent with all the necessary potential requirements. One of these electro-mechanical systems consists of a controlled-motorized wiper that explores all an OS surface until it engages with a pin on an OS surface and brings it to the final home location reorienting an OS. This mechanism is expected to be robust to the incoming OS orientation and to reorient it to the desired position using only one degree of freedom rotational actuator

Improving Automated Operations of Heavy-Duty Manipulators with Modular Model-Based Control Design

The rapid development of robotization and automation in mobile working machines aims to increase productivity and safety in many industrial sectors. In heavy-duty applications, hydraulically actuated manipulators are the common solution due to their large power-to-weight ratio. As hydraulic systems can exhibit nonlinear dynamic behavior, automated operations with closed-loop control become challenging. In industrial applications, the dexterity of operations for manipulators is ensured by providing interfaces to equip product variants with different tool attachments. By considering these domain-specific tool attachments for heavy-duty hydraulic manipulators (HHMs), the autonomous robotic operating development for all product variants might be a time-consuming process. This thesis aims to develop a modular nonlinear model-based (NMB) control method for HHMs to enable systematic NMB model reuse and control system modularity across different HHM product variants with actuators and tool attachments. Equally importantly, the properties of NMB control are used to improve the high-performance control for multi degrees-of-freedom robotic HHMs, as rigorously stability-guaranteed control systems have been shown to provide superior performance. To achieve these objectives, four research problems (RPs) on HHM controls are addressed. The RPs are focused on damping control methods in underactuated tool attachments, compensating for static actuator nonlinearities, and, equally significantly, improving overall control performance. The fourth RP is introduced for hydraulic series elastic actuators (HSEAs) in HHM applications, which can be regarded as supplementing NMB control with the aim of improving force controllability. Six publications are presented to investigate the RPs in this thesis. The control development focus was on modular NMB control design for HHMs equipped with different actuators and tool attachments consisting of passive and actuated joints. The designed control methods were demonstrated on a full-size HHM and a novel HSEA concept in a heavy-duty experimental setup. The results verified that modular control design for HHM systems can be used to decrease the modifications required to use the manipulator with different tool attachments and floating-base environments