03.1 Project Proposal
Introduction
Modern manufacturing has increasingly favored physically vertical layouts to overcome spatial constraints and improve production efficiency. For example, companies such as Tesla Inc. utilizes multi-story and vertical integration in their facilities production lines. By limiting the distance material is required to travel and increasing the usable volume to incorporate various manufacturing processes, vertically integrating manufacturing enhances production without the requirement of horizontal expansion. Simply put, instead of spreading operations outward along a production line, materials are passed autonomously between floors or stored vertically, allowing higher production within a smaller footprint. To accomplish this, robotic mechanisms with spatial awareness and sensing are required, capable of picking up and placing objects not typically handled by conventional elevators or conveyors. This necessitates a mechanism with more complex motion and higher degrees of freedom.
Problem Statement
The challenge is to design a robotic mechanism capable of transferring objects from a lower elevation to a higher one while sorting them according to color. The mechanism must operate within a defined 2D reachable workspace, while providing precise positioning and coordinated motion to reach, grasp, and place each object at its designated location. Because the objects are delicate, the motion path, acceleration, and grasping action must be carefully considered to minimize excessive inertial effects and force during handling. The design must achieve this functionality through appropriate kinematic configuration and mechanical design rather a linear system (e.g., conveyor or elevator). The motion involves both horizontal and vertical movement, requiring the mechanism to work in a coordinated way rather than relying on a simple single-axis or linear system.
Mechanism
As shown in Fig. 1, the system picks up materials from the bottom level, then dependent on the color moves to the upper-level storage location at various accelerations throughout the reachable workspace. To accomplish this, a gantry, arm and claw system is required to deliver the required three degrees of motion. (1) A horizontal gantry translation moving the objects along the X-axis from shelf-to-shelf. (2) A vertical extension of the arm to pick up and move the object from elevation to elevation along the Y-axis. (3) A claw grasping motion is required to carefully secure and move delicate items from initial to final position.
Proposed Scope
For this project we intend to produce a working prototype, while addressing three distinct problems. (1) Design and fabrication: We will design and fabricate the gantry translation system, arm extension, and claw gripper needed to execute the motion described in the problem statement. (2) Kinematic and motion analysis: Conduct position, velocity and acceleration analysis for each link, along with tracking the objects motion in the spatial frame. This will ensure the target positions, accelerations, and claw strength remains appropriate for our goal of moving delicate objects across elevations, with additional consideration to the mechanical forces applied during pickup. (3) Color sorting integration: A color detection system will be implemented using an Arduino-based color sensor to identify the objects color and adjust the corresponding gripping behavior.
To fully address the problem, each of these components must be carefully coordinated to achieve the specified motion. While this project is idealized compared to the solutions mentioned in the introduction, this project establishes a foundation for more a more advanced continuation. Future improvements could include adding additional degrees or freedom (e.g., rotational) to the claw mechanism or exploring more adaptable gripper designs such as soft actuators or mechanical metamaterials.
Preliminary Design
The robotic system consists of three coordinated subsystems that enable horizontal movement, vertical lifting, and object grasping. Each motion is driven by a dedicated motorized mechanism designed to provide smooth and precise control within the workspace. The combined operation of these three motions allows the robot to reach, lift, and place objects accurately while maintaining stable and gentle handling.
Gantry’s Horizontal Translation Motion: As shown in Fig. 2a, the horizontal motion of the system is driven by a motorized belt–rail mechanism mounted at the top of the gantry. When the motor rotates, it moves a slider along the rail, carrying the entire lifting and grabbing assembly horizontally across the working area. The Gruebler-Kutzbach Equation for this gantry is shown below:
Arm’s Vertical Extension Motion: As shown in Fig. 2b, the arm’s vertical motion is actuated by a scissor link mechanism connected to a slider–crank actuated with a servo motor. As the crank moves, the deployment angle of the scissor linkages extends or retracts accordingly, moving the arm up and down. The Gruebler-Kutzbach Equation for this arm is shown below:
Claw’s Grasping Mechanism Motion: As shown in Fig. 2c, the claw’s grasping action is controlled by a servo motor mounted on a prismatic joint that drives the central slider of the claw. The motion of this slider transmits through linkages to open or close the claw fingers, enabling the system to grip or release objects. The Gruebler-Kutzbach Equation for this claw is shown below: