Initial Proposal - Team 9

Introduction

In this project, we aim to design a single actuator mechanical linkage system that achieves the goal of continuously loading and processing (i.e. stamping, cutting, flattening) mass amounts of material. This will be accomplished in three simultaneous phases- a loading phase, a stamping phase, and a package translation phase. The focus of this project will be on the loading phase, which will include a mechanism that achieves a complex motion profile through both latching onto the package and translating it onto a new surface. The projected product can be used in a wide range of applications, most notably in the manufacturing industry where products must be labeled/embossed and materials must be cut/flattened into specific package volumes before being processed further. 

Description of Complexities Involved

Since this mechanism operates through a combination of three simultaneous phases, the synchronization of all three required sub-mechanisms will be difficult to achieve. The mechanism moving the package needs to be inactive when the package is being loaded and stamped while the vertical stamping mechanism needs to be fully in synchronization with the loading mechanism. 

Furthermore, some of the sub-mechanisms will involve further coupled movements. The loading mechanism will need to follow a specified path to translate the package and it will also need to incorporate a mechanical object manipulator that can physically latch onto the object at the same time. The coordination profile of these movements will be difficult and even impossible to achieve in some scenarios with simple joints. 

Description of Proposed Mechanism

In the loading phase, the proposed mechanism is a combination of a rotational and linear planar joint coupled to a rotating bracket mechanism that dictates the semicircle motion profile of the manipulator. As the manipulator body translates linearly relative to the rotational joint, connected binary links will open and close the end effector [Fig. 1]. 

In the stamping phase, a stamping pad (or a cutter/flattener) will be vertically constrained to move only in the z-axis. The oscillatory movement of stamping will be dictated using cams synchronized with the movement of the loading mechanism via a crank slider mechanism. 

In the translation phase, the package will move along a conveyor belt that is stepped (i.e. noncontinuous) and out of phase with the loading and stamping mechanisms. This will be done with a gear-coupled mechanism that slots into a wheel driving the conveyor belt [Fig. 2]. This timing is driven by the camshaft of the stamping mechanism and can be tuned by choosing the orientation of the output gear relative to the camshaft. 

The synchronization of all three phases will be driven by a single input to the camshaft and carefully designed linkage systems (crank slider, gears) that translate motion. 

Depictions of similar mechanism systems are included below: 

Fig. 1: Model of coupled end effector/manipulator body 

Fig. 2: Depiction of stepped conveyor belt mechanism 

Proposed Scope of Work

The focus of this project will be on the object loading phase, which includes the manipulator body and the end effector. At the very minimum, the completed product will be able to hover over an object, pick it up, and place it at another specified location in one coupled motion. We predict that we will also be able to complete the coupled stamping and package translation mechanisms as well, however, we have been advised that this borders on the extremes of the time constraints we are given. 

Analysis that will be required prior to the final development of the mechanism would be timing. The coordination profile between the loading, stamping, and translation mechanisms will need to be simulated in a program to prevent the mechanism from binding/malfunctioning. Even further within the loading mechanism, the coordination and force profile of the end effector needs to be analyzed to make sure that the mechanism actually makes sufficient contact with the package in order to lift it from the pickup location. This analysis will determine the required linkage lengths, angles, and in the case of the translation mechanism, orientations relative to a driveshaft in order to ensure smooth motion. 

Designing this robot is the most exciting part of this project. All of us are in Longhorn Racing, which means we have a lot of simulation and design implementation background. We all work in very mechanism-heavy subsystems (steering, suspension, and engine development) as well, so this project is an exciting opportunity for us to work on systems that feel very familiar. The most challenging aspect of this project would be the manufacturing of all the components. Since there are a lot of coupled mechanisms, there are a lot of opportunities for the mechanism to bind if the right tolerances are not properly achieved. Especially since we do not own the equipment ourselves (3D printers, laser cutters), we are not able to tune or precisely estimate the tolerances of our prototyped products. 

Preliminary Design Ideas

Pictured below is the proposed design idea for the loading mechanism [Fig. 3]. The upper crossbar (pictured in green) is constrained via an axle to the walls of the outer housing but allowed to rotate concentric to that axle. The outer bracket mechanism (pictured in blue) that dictates the path of the end effector is driven by a crank-slider input coupled to the stamping mechanism camshaft. The lower part of the manipulator mechanism (pictured in red) contains the two binary links that control the opening and closing of the end effector. This lower part is allowed to slide freely vertically through the upper crossbar via a linear bearing. 

Fig. 3: Proposed loading mechanism 

The stamping mechanism camshaft will be similar to the design of a camshaft in an engine, which is used to push valves down. Ideally, as the cam is rotating, the lobe will push the stamping pad down until it reaches the maximum displacement, then raise it as the cam reaches its minimum displacement point. This motion will be constrained by rails the pad rests on and springs to return the mechanism to its original position. 

The non-continuously geared conveyor belt takes inspiration from the mechanism shown in figure 2 above. The gear will be connected straight to the camshaft, which is powered by the motor. The driven gear will contain a rod on the end that acts as a slider. This slider then interfaces with slots on the conveyor wheel, and as the driven gear turns, the wheel will incrementally turn through tangential contact. 

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