When
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brainstorming a linkage-based project for this class,
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one idea that we kept coming back to
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was a robotic arm.
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Many industry robotic arms are heavy and expensive, requiring actuators at each joint. Although this may be necessary for complex motion profiles, these types of robotic arms are over-specked for more simple use cases. To solve this problem, we set out to develop a robotic arm from a linkage system that can carry out a complex motion from a
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single input
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A common setting for robotic arms are assembly lines and warehouses. See the video linked below, as well as many of the other videos available on the webpage. Each arm has actuators at various joints, each greatly increasing the cost to produce and purchase these arms. A robotic arm with a singular input would be cheaper to manufacture and purchase, while still maintaining efficiency along the assembly line. Thus, we decided on an assembly line arm and grabber for our project.
Our robotic arm will take up as little space as possible, where it is able to pick up objects on the assembly line, travel horizontally along the same axis, and deposit the object at a new location along that axis. We aim to have the motors in the base, an arm composed mainly of four-bar linkages, and a claw gripper. The claw will have an escapement mechanism to cycle between open and closed positions, and gears that rotate two four-bar linkages. The claw is able to pick up various size objects with different weights. Additionally, we plan on automating the process of picking and placing to mimic the function of the arm working on an actual assembly line.
Analysis that will need to be performed prior to the fabrication includes the following. We need to understand the motion profiles of the linkages as well as the rotary motion from the base to the claw. Furthermore, we will analyze the force profile of the grabber, the arm’s geometry/dimensions, and overall design via SolidWorks simulation. We would like to use the minimum amount of materials so the arm can take up as little space as possible, and we need to analyze the rotation of the base with respect to the other components such as wires.
The most exciting part of this project is learning how to design a functioning robotic arm. Specifically, going from an idea, to drawings, to CAD models, to fabrication. We are really excited about using the knowledge gained in lecture about four-bar linkages and applying it to the real world application of building a robotic arm that streamlines the manufacturing process. The main challenge will be to design a linkage system to account for the complex motion of the arm, an escapement mechanism to alternate between open and closed positions of the gripper, and powering these seemingly independent mechanisms in concert with a single rotary input. Furthermore, it will be a challenge to automate this process in addition to using our mechanical engineering knowledge for the build itself. The greatest constraint of all in this project is the limited timeframe in which we have to complete it in addition to balancing the other assignments in this course.
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. For example, the arm should be able to rotate analogously to a human shoulder joint, extend through the use of a modified elbow, and grab an object like a hand. Compared to a multi-actuator arm, our mechanism is more cost-effective, robust, and has a planar form factor which allows them to be added in parallel.
One common use of a robotic arm is to move an object between conveyor belts on an assembly line in warehouses. Although conveyor splitters can be used for this application, if the part needs to be lifted and oriented differently during a particular stage of production, a robotic arm can fulfill this requirement, and do so at a less cost than complex, multi-actuator arms. The video below demonstrates various robotic arms in application.
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