Actuators for a space manipulator

The robotic manipulator can be decomposed into distinct subsytems. One particular area of interest of mechanical subsystems is electromechanical actuators (or drives). A drive is defined as a motor with an appropriate transmission. An overview is given of existing, as well as state-of-the-art drive systems. The scope is limited to space applications. A design philosophy and adequate requirements are the initial steps in designing a space-qualified actuator. The focus is on the d-c motor in conjunction with several types of transmissions (harmonic, tendon, traction, and gear systems). The various transmissions will be evaluated and key performance parameters will be addressed in detail. Included in the assessment is a shuttle RMS joint and a MSFC drive of the Prototype Manipulator Arm. Compound joints are also investigated. Space imposes a set of requirements for designing a high-performance drive assembly. Its inaccessibility and cryogenic conditions warrant special considerations. Some guidelines concerning these conditions are present. The goal is to gain a better understanding in designing a space actuator

Conception et validation expérimentale d’un robot manipulateur 6 DDL actionné par des embrayages magnétorhéologiques semi-délocalisés

L’utilisation de robots manipulateurs est un standard en industrie pour automatiser deschaînes de production. Ces robots sont précis, robustes et rapides. Pour atteindre leurperformance, ils sont conçus avec des actionneurs puissants et ils sont faits de pièces mas-sives. Lorsqu’ils sont en utilisation, ces robots doivent être placés dans une zone clôturéepuisqu’ils représentent un danger pour les travailleurs. Pour pallier ce problème, l’industriese tourne vers les robots collaboratifs. Ces robots normalisés sont conçus pour être sansdanger pour les utilisateurs ce qui permet une intégration facile et abordable. Plusieursstratégies comme l’utilisation d’algorithmes de contrôle et des designs mécaniques sontutilisés pour réduire le danger d’un robot manipulateur pour un utilisateur.Ce mémoire présente un manipulateur de 6 degrés de liberté (DDL) actionné par des em-brayages magnétorhéologiques (MR) semi-délocalisés. Le manipulateur a été conçu pouratteindre ou dépasser les performances des bras robots collaboratifs commerciaux dans lebut de valider la capacité des actionneurs MR pour des applications en robotique colla-borative. Le manipulateur a été dimensionné pour avoir des spécifications similaires auxrobots collaboratifs UR5 et WAM. Les spécifications ont été validées par les mesures ex-périmentales. Le manipulateur a une masse en mouvement de seulement 5.3 kg et il peutdéplacer une masse de 4.5 kg à 1 m/s avec une portée de 0.885 m. De plus, la bandepassante en force est au-dessus de 50 Hz et la friction des joints est de maximum 10 % ducouple maximum du joint. Aussi, le manipulateur est intrinsèquement sécuritaire et tolé-rant aux impacts. En somme, il est possible de dire qu’un actionnement MR semi-délocaliséest une solution prometteuse pour la robotique collaborative, mais d’autres mesures ex-périmentales avec le manipulateur sont nécessaires pour que la technologie MR atteigneson plein potentiel en robotique. En autre, il serait nécessaire de mesurer la capacité dumanipulateur à produire des murs virtuels, de mesurer la précision du positionnement dumanipulateur et de mesurer l’énergie transmise par le bras au moment d’un impac

Rogue Rotary - Modular Robotic Rotary Joint Design

This paper describes the design process from ideation to test validation for a singular robotic joint to be configured into a myriad of system level of robots

A 17 degree of freedom anthropomorphic manipulator

A 17 axis anthropomorphic manipulator, providing coordinated control of two seven degree of freedom arms mounted on a three degree of freedom torso-waist assembly, is presented. This massively redundant telerobot, designated the Robotics Research K/B-2017 Dexterous Manipulator, employs a modular mechanism design with joint-mounted actuators based on brushless motors and harmonic drive gear reducers. Direct joint torque control at the servo level causes these high-output joint drives to behave like direct-drive actuators, facilitating the implementation of an effective impedance control scheme. The redundant, but conservative motion control system models the manipulator as a spring-loaded linkage with viscous damping and rotary inertia at each joint. This approach allows for real time, sensor-driven control of manipulator pose using a hierarchy of competing rules, or objective functions, to avoid unplanned collisions with objects in the workplace, to produce energy-efficient, graceful motion, to increase leverage, to control effective impedance at the tool or to favor overloaded joints

Design and control of SLIDER: an ultra-lightweight, knee-less, low-cost bipedal walking robot

Most state-of-the-art bipedal robots are designed to be highly anthropomorphic and therefore possess legs with knees. Whilst this facilitates more human-like locomotion, there are implementation issues that make walking with straight or near-straight legs difficult. Most bipedal robots have to move with a constant bend in the legs to avoid singularities at the knee joints, and to keep the centre of mass at a constant height for control purposes. Furthermore, having a knee on the leg increases the design complexity as well as the weight of the leg, hindering the robot’s performance in agile behaviours such as running and jumping. We present SLIDER, an ultra-lightweight, low-cost bipedal walking robot with a novel knee-less leg design. This nonanthropomorphic straight-legged design reduces the weight of the legs significantly whilst keeping the same functionality as anthropomorphic legs. Simulation results show that SLIDER’s low-inertia legs contribute to less vertical motion in the center of mass (CoM) than anthropomorphic robots during walking, indicating that SLIDER’s model is closer to the widely used Inverted Pendulum (IP) model. Finally, stable walking on flat terrain is demonstrated both in simulation and in the physical world, and feedback control is implemented to address challenges with the physical robot

High speed, precision motion strategies for lightweight structures

Research on space telerobotics is summarized. Adaptive control experiments on the Robotic Arm, Large and Flexible (RALF) were preformed and are documented, along with a joint controller design for the Small Articulated Manipulator (SAM), which is mounted on the RALF. A control algorithm is described as a robust decentralized adaptive control based on a bounded uncertainty approach. Dynamic interactions between SAM and RALF are examined. Unstability of the manipulator is studied from the perspective that the inertial forces generated could actually be used to more rapidly damp out the flexible manipulator's vibration. Currently being studied is the modeling of the constrained dynamics of flexible arms