Design and Prototyping of a 3DOF Worm-drive Robot Arm

PEARLDOI for this publication Labels There are no labels on this output. Add labels Many designs for robot arms exist. Here we present an affordable revolute arm, capable of executing simple pick-and-place tasks. The arm employs a double parallelogram structure, which ensures its endpoint angle in the plane of the upper arm remains fixed without the need for additional actuation. Its limbs are fabricated from circular tubes made from bonded carbon fiber, to ensure low moving mass while maintaining high rigidity. All custom structural elements of the arm are produced via 3D printing. We employ worm-drive DC motor actuation to ensure that stationary configurations are maintained without the necessity of continuous motor power. Our discussion encompasses an analysis of the arm’s kinematics. A simulation of the arm’s operation was carried out in MATLAB, revealing key operational metrics. In conclusion, we achieved extrinsic endpoint position tracking by implementing its inverse kinematics and PID control using a microcontroller. We also demonstrate the arm’s functionality through simple movement tracking and object manipulation tasks

Biological Plausibility of Arm Postures Influences the Controllability of Robotic Arm Teleoperation

International audienceObjective: We investigated how participants controlling a humanoid robotic arm's 3D endpoint position by moving their own hand are influenced by the robot's postures. We hypothesized that control would be facilitated (impeded) by biologically plausible (implausible) postures of the robot. Background: Kinematic redundancy, whereby different arm postures achieve the same goal, is such that a robotic arm or prosthesis could theoretically be controlled with less signals than constitutive joints. However, congruency between a robot's motion and our own is known to interfere with movement production. Hence, we expect the human-likeness of a robotic arm's postures during endpoint teleoperation to influence controllability. Method: Twenty-two able-bodied participants performed a target-reaching task with a robotic arm whose endpoint's 3D position was controlled by moving their own hand. They completed a two-condition experiment corresponding to the robot displaying either biologically plausible or implausible postures. Results: Upon initial practice in the experiment's first part, endpoint trajectories were faster and shorter when the robot displayed human-like postures. However, these effects did not persist in the second part, where performance with implausible postures appeared to have benefited from initial practice with plausible ones. Conclusion: Humanoid robotic arm endpoint control is impaired by biologically implausible joint coordinations during initial familiarization but not afterwards, suggesting that the human-likeness of a robot's postures is more critical for control in this initial period. Application: These findings provide insight for the design of robotic arm teleoperation and prosthesis control schemes, in order to favor better familiarization and control from their users

Enhancing the Performance of a Biomimetic Robotic Elbow-and-Forearm System Through Bionics-Inspired Optimization

This paper delineates the formulation and verification of an innovative robotic forearm and elbow design, mirroring the intricate biomechanics of human skeletal and ligament systems. Conventional robotic models often undervalue the substantial function of soft tissues, leading to a compromise between compactness, safety, stability, and range of motion. In contrast, this study proposes a holistic replication of biological joints, encompassing bones, cartilage, ligaments, and tendons, culminating in a biomimetic robot. The research underscores the compact and stable structure of the human forearm, attributable to a tri-bone framework and diverse soft tissues. The methodology involves exhaustive examinations of human anatomy, succeeded by a theoretical exploration of the contribution of soft tissues to the stability of the prototype. The evaluation results unveil remarkable parallels between the range of motion of the robotic joints and their human counterparts. The robotic elbow emulates 98.8% of the biological elbow's range of motion, with high torque capacities of 11.25 Nm (extension) and 24 Nm (flexion). Similarly, the robotic forearm achieves 58.6% of the human forearm's rotational range, generating substantial output torques of 14 Nm (pronation) and 7.8 Nm (supination). Moreover, the prototype exhibits significant load-bearing abilities, resisting a 5kg dumbbell load without substantial displacement. It demonstrates a payload capacity exceeding 4kg and rapid action capabilities, such as lifting a 2kg dumbbell at a speed of 0.74Hz and striking a ping-pong ball at an end-effector speed of 3.2 m/s. This research underscores that a detailed anatomical study can address existing robotic design obstacles, optimize performance and anthropomorphic resemblance, and reaffirm traditional anatomical principles

Development and Characteristics of a Highly Biomimetic Robotic Shoulder Through Bionics-Inspired Optimization

This paper critically analyzes conventional and biomimetic robotic arms, underscoring the trade-offs between size, motion range, and load capacity in current biomimetic models. By delving into the human shoulder's mechanical intelligence, particularly the glenohumeral joint's intricate features such as its unique ball-and-socket structure and self-locking mechanism, we pinpoint innovations that bolster both stability and mobility while maintaining compactness. To substantiate these insights, we present a groundbreaking biomimetic robotic glenohumeral joint that authentically mirrors human musculoskeletal elements, from ligaments to tendons, integrating the biological joint's mechanical intelligence. Our exhaustive simulations and tests reveal enhanced flexibility and load capacity for the robotic joint. The advanced robotic arm demonstrates notable capabilities, including a significant range of motions and a 4 kg payload capacity, even exerting over 1.5 Nm torque. This study not only confirms the human shoulder joint's mechanical innovations but also introduces a pioneering design for a next-generation biomimetic robotic arm, setting a new benchmark in robotic technology

Design, rapid manufacturing and modeling of a reduced-scale forwarder crane with closed kinematic chain

Forestry cranes are of paramount importance in forestry operations, so considerable efforts have been carried out to improve their performance in recent years. However, all these efforts have focused on automation technology, leaving aside other alternatives for improvement. Among these alternatives is model-based design, which has the potential to be game-changing for the forest industry. Because research on model-based design is almost non-existent for forestry cranes, there are many gaps that should be filled before presenting improved designs of forestry cranes. The purpose of this article is to fill two of those gaps: (1) the high cost-benefit ratio and safety concerns when testing new designs, components or algorithms in industrial-scale forestry cranes and (2) the dynamic modeling of forestry cranes as mechanical systems with closed kinematic chain. Under these premises, this article first presents a reduced-scale platform resembling a forwarder crane with closed-kinematic chain, where the components of the mechanical structure are manufactured with 3D printing technology, and second, the modeling and experimental validation of the reduced-scale forwarder, where the closed kinematic chain is considered as a system of multiple constrained open kinematic chains. For the experimental validation, a comparison between both experimental and simulation results is presented. Results presented in this article broaden the options to design and test new concepts and/or technology to improve forestry cranes performance

Diseño de extremidades móviles para robot de telepresencia en hospitales

Las características de interacción de un robot social son de gran importancia, en especial cuando su desempeño depende de generar confianza con el usuario; este es el caso de un robot de telepresencia para diagnóstico psicológico en hospitales. Sabiendo que muchas alternativas actuales no cuentan con rasgos atractivos o familiares que incentiven su uso, este trabajo de tesis tiene como objetivo desarrollar el diseño de un sistema de brazos y cabeza móviles de un robot de telepresencia para diagnosticar y tratar afecciones mentales en hospitales de Perú, como parte de la investigación del Proyecto Concytec 160-2020. Dicho diseño tendrá como fin incrementar la aceptabilidad del robot brindándole expresividad a través de rasgos y movimientos semejantes al humano. El diseño final consta de cuatro grados de libertad en el brazo y dos grados de libertad en la cabeza actuados por servomotores de disco que transmiten de forma directa y por correas dentadas. Las articulaciones están unidas por planchas y piezas impresas para otorgar una forma antropomórfica, con medidas de una persona peruana de estatura promedio de 1.65 m (hombro-codo de 33 cm, codo-muñeca de 25 cm y una cabeza proporcional a la altura de 20 cm). Además, se agregaron otros aspectos de expresividad como iluminación de los ojos por matrices led y señales de audio a través de parlantes. Finalmente, se realizaron pruebas de funcionamiento mediante la implementación del prototipo de un brazo con piezas fabricadas mediante impresión 3D

Reachy, a 3D-printed human-like robotic arm as a testbed for human-robot control strategies

To this day, despite the increasing motor capability of robotic devices, elaborating efficient control strategies is still a key challenge in the field of humanoid robotic arms. In particular, providing a human "pilot" with efficient ways to drive such a robotic arm requires thorough testing prior to integration into a finished system. Additionally, when it is needed to preserve anatomical consistency between pilot and robot, such testing requires to employ devices showing human-like features. To fulfill this need for a biomimetic test platform, we present Reachy, a human-like life-scale robotic arm with seven joints from shoulder to wrist. Although Reachy does not include a poly-articulated hand and is therefore more suitable for studying reaching than manipulation, a robotic hand prototype from available third-party projects could be integrated to it. Its 3D-printed structure and off-the-shelf actuators make it inexpensive relatively to the price of an industrial-grade robot. Using an open-source architecture, its design makes it broadly connectable and customizable, so it can be integrated into many applications. To illustrate how Reachy can connect to external devices, this paper presents several proofs of concept where it is operated with various control strategies, such as tele-operation or gaze-driven control. In this way, Reachy can help researchers to explore, develop and test innovative control strategies and interfaces on a human-like robot