Design of Anthropomorphic Robot Arm: ARA-1

Nielsen, Lee

4. term

Design of Mechanical Systems, Master

2008

66

AAU-Bot1 er en menneskelignende tobenet robot, der udvikles på Aalborg Universitet i et samarbejde mellem Mekaniske Systemer og Elektriske Systemer. Robotten blev oprindeligt designet til at efterligne menneskets hæl-tå-gang. For at robotten også kan interagere med mennesker, fx give hånd, kræver armen mere bevægelse end den nuværende simple skulderrotation. Dette projekt designer en let og strømbesparende antropomorf robotarm (ARA), der er tiltænkt syv frihedsgrader (de uafhængige bevægelser i leddene) og et arbejdsområde som en menneskelig arm. Den første konceptudgave, der skal fremstilles og monteres på AAU-Bot1, er begrænset til fire frihedsgrader. Ud fra litteraturen er typiske håndledsbaner for gang og håndtryk fastlagt. De tilsvarende ledbevægelser er beregnet med en vægtet og dæmpet pseudoinvers Jacobian—en matematisk metode til at oversætte en ønsket håndbane til ledvinkler i en redundant arm. Standard kinematiske og inverse dynamiske analyser blev brugt til at estimere bevægelser og kræfter, og en optimering baseret på Complex-metoden blev anvendt for at reducere energiforbruget og undgå baner, der ville kollidere med torsoen. Resultaterne har guidet valg af gear og aktuatorer fra kataloger, mens de strukturelle dele er designet med enkle beregninger og praktiske retningslinjer. Konceptet har fire frihedsgrader, menneskelignende proportioner og god manipulérbarhed, en samlet startmasse på cirka 5,8 kg og kan løfte en last på 2 kg. På grund af delte designdele giver det en tilføjet masse på cirka 4 kg per arm for AAU-Bot1. Leddelene er serielt opbyggede drejeled (revolute joints) med en fordeling, der ligner den menneskelige arm. Armen kan udføre de håndbevægelser, der indgår i standard gang og et håndtryk, og er robust nok til andre opgaver. Fremadrettet bør massen yderligere reduceres ved brug af specialdesignede gear og ekstra gearing for at minimere motorstørrelser, og designet udvides med tre ekstra frihedsgrader for at nå en fuld 7-frihedsgrad arm.

AAU-Bot1 is a human-like biped robot being developed at Aalborg University through collaboration between the Departments of Mechanical Systems and Electrical Systems. The robot was initially designed to reproduce the human heel-to-toe gait. To let it interact with people—for example, to shake hands—the arm needs more motion than the current simple shoulder pitch. This project designs a lightweight, low-power anthropomorphic robot arm (ARA) intended to have seven degrees of freedom (DoF—the independent ways joints can move) and a workspace similar to a human arm. The first concept to be manufactured and mounted on AAU-Bot1 is limited to four DoF. From the literature, typical wrist paths for walking and handshaking were identified. The corresponding joint motions were computed using a weighted, damped pseudo-inverse Jacobian—a mathematical method that converts a desired hand path into joint angles in a redundant arm. Standard kinematic and inverse dynamic analyses estimated motions and forces, and an optimization based on the Complex method was applied to reduce power use and avoid paths that would collide with the torso. These results guided the selection of gears and actuators from catalogs, while structural parts were designed with simple calculations and practical design rules. The concept has four DoF, human-like proportions and manipulability, an initial total mass of about 5.8 kg, and can carry a 2 kg payload. Because some design parts are shared, the added mass on AAU-Bot1 is about 4 kg per arm. The joints are serial revolute joints distributed like those in a human arm. The arm can perform the hand motions involved in standard gait and a handshake and is strong enough for other tasks. Next steps are to further reduce mass using custom gears and additional gearing to allow smaller motors, and to extend the design by three more DoF to achieve a full seven-DoF arm.

[This abstract was generated with the help of AI]

design ; dynamics ; anthropomorphic ; arm ; robot ; human handshake ; human walk ; concept

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