Construction of a Selective Compliance Articulated Robot Arm : And evaluation of its accuracy

The concept of a robotic manipulator is widely used throughout many industries. In this project, a manipulator of the type SCARA, selective compliance articulated robot arm, is constructed. The aim was to examine how such a robot could be constructed using 3D-printing and how accurate it would be. O...

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Bibliographic Details
Main Authors: Labbé, Anton, Ström, Benjamin
Format: Others
Language:English
Published: KTH, Mekatronik 2021
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Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-296163
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Summary:The concept of a robotic manipulator is widely used throughout many industries. In this project, a manipulator of the type SCARA, selective compliance articulated robot arm, is constructed. The aim was to examine how such a robot could be constructed using 3D-printing and how accurate it would be. Other than 3D-printing, parts in the form of guiding rods, lead screw, bearings, pulleys and timing belts were used. Together with a microcontroller, the robot operates using three stepper motors. In the end it resulted in a SCARA with reasonable accuracy considering the methods used, more specifically the largest average error was 3.6cm in the X direction and 2.3 cm in the Y direction. The largest drawback of the final construction was the negative balance between tightening the belts and friction in the inner joint. Tightening the belts meant larger friction and thereby undesired movement properties. Doing the opposite meant that the belts could start slipping and enabled backlash. === Konceptet av en robotarm används brett inom många industrier. Detta projekt syftar till att konstruera en robot avtypen SCARA, selective compliance articulated robot arm. Målet var att undersöka hur en sådan robot kan 3D-printas och dess precision. Förutom 3D-printade delar användes även guidestänger, kullager, kamremmar och remskivor. Robotens rörelser styrs tillsammans med en mikrokontroller och tre stegmotorer. Med tillvägagångssätten i åtanke resulterade projektet in en SCARA med rimlig precision. Mer specifikt var medelfelet 3.6 cm i X-led och 2.3 cm i Y-led. Den största nackdelen med den slutgiltiga konstruktionenvar den negativa jämvikten mellan att spänna kamremmarna och friktionen i den inre armleden. Att spänna kamremmarna innebar en ökning i friktion och därmed oönskade rörelseegenskaper. Att göra tvärtom innebar att bältena löpte större risk att glida ur och möjliggjorde dödgång.