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Robot mechanisms are often used to tackle complex problems in industry from manufacturing to transportation. However, complex mechanisms are seldom seen in the household despite their great potential to automate everyday tasks. Our project will focus on automating eating. For example, when eating Oreos, it is difficult to get the perfect amount of sogginess without the Oreo breaking apart and getting messy hands. Our objective is to create a mechanism that automates the act of dipping Oreos while maximizing the use of mechanical components and minimizing our reliance on software.
Problem
Messy hands and falling cookies are issues that we all face. Having to dip a cookie in milk is a fundamental life experience but you are left with Oreo residue after enjoying the snack. An additional problem when dipping your cookie of choice in milk is getting the perfect level of sogginess.
Proposed Mechanism
We would like to create a mechanism that allows its users to enjoy milk and cookies hands-free. The mechanism will be manually loaded vertically with a cookie and then moved to place the cookie in milk. Once the cookie has reached the desired level of sogginess the cookie will be lifted and actuated to a horizontal When eating Oreo cookies, a few problems can arise and be rather annoying. For one, it is difficult to dip the cookie for the right amount of time to get a consistent sogginess. Also, if soggier Oreos are the preference, it is difficult to get to that point without having the cookie break off into the milk. Eating Oreos is also difficult when your hand is too big to fit in the glass and the cookie can't reach the milk. To get a mechanism to alleviate all these problems is going to bring up many complexities due to the intermittent motion, complex position profiles, mechanical timing components, and the grabbing mechanism.
One complexity that will arise is loading the cookies into the arm which is an intermittent motion problem. Indeed, when a person eats cookies, they pick cookies from the container when they are ready to eat. Accordingly, we need to have a part of the mechanism load cookies at a set interval to mimic a normal eating pace. Another component that we foresee being difficult is the complex position profile. The proposed robot is meant to be able to grab the cookie, displace it some amount in the x, y, and z directions, dip it, retract, and then rotate the cookie to feed the operator. This brings a lot of complexity to our mechanism design. Certainly, to minimize the number of motors and controllers we use, we will have to get creative with the linkage design which probably limits a simple four-bar linkage. We may also see issues in bearing the weight of multiple motors if we choose to go that route. Implementing mechanical timing with gears, cams, or another mechanism will also prove to be a challenge as we need to match the frequency of the loading mechanism to the movement of the arm. This will require a lot of testing and validation. Finally, the robot needs a gripper to grab the cookies which may be difficult to design to both be functional and food safe.
Proposed Mechanism
A mechanism we believe could achieve our desired path of motion for the consumption of a cookie is primarily composed of a modified slider crank and a Geneva mechanism. In our design, the Geneva mechanism acts as a cookie supply. The Geneva mechanism will be spring-loaded with Oreos and its intermittent motion will allow for the Oreos to be re-loaded and picked by the end effector. The slider crank and Geneva mechanism will share the same input crank, which will allow for the time synchronization of the end effector and the Geneva mechanism throughout our desired output motion. In our mechanism the slider is a ternary link; this configuration allows us to connect our end effector whose angular position depends on the position of the input crank. The motion of the end effector is restricted by a belt that wraps around a gear that shares a pin joint with the ternary link. As of now, there is still more development needed in the mechanism design that would allow the end effector to temporarily uncouple with the motion of the input crank and actuate in the clockwise direction to a position that benefits the consumption of the user. This motion is in orange in the image below.
The proposed scope of work for the final project
- To overcome our problem, we are designing a mechanism that moves a cookie from one location to another (for a certain period)
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Figure 1: Proposed cookie dipper mechanism
Inspiration for this design came primarily from the semiconductor industry which also deals with transporting circular objects. In their case, the objects are silicon wafers, and examples of their mechanisms are shown below. In this mechanism, the arm slides underneath a wafer picks it up, and places it elsewhere. We also took inspiration from the industrial manufacturing industry for more ideas on how to implement a gripper mechanism onto our arm. That example is also shown below.
Figure 2: Example from the semiconductor industry
Figure 3: Example from industrial manufacturing
Scope of work
Our project's scope of work will be limited to picking and placing small lightweight items. As of now, we are limiting the amount of time that the Oreo is dipped to be fixed, however in future iterations the amount of time dipped and therefore the sogginess of the cookie could be subject to variability depending on user preference. The core goal of this project is to build a pick and place mechanism that relies on intermittent motion to achieve the correct timing of the outputs. We plan to realize this goal with the following plan:
- Brainstorm additional mechanism configurations as well as problems that we may encounter and potential with their respective solutions.
- CAD an arm the Geneva and slider crank mechanism and plot the associated position, velocity, force, and motion profiles.
- A Conduct a critical review of mechanical design and consider the strength of links, joint integrity, motor power, etc.
- Create a simple prototype with cardboard etc to validate that the design to roughly maps map the intended trajectory
- Plan out Arduino pin connections and skeleton of code to obtain desired motion for end effector if necessary. (Redo 3 if if necessary)
- Laser cut/3D print the parts and configure Arduino to construct a functional prototype.
- Review the functionality and integrity of the prototype and reinforce/iterate if necessary.
- Final product manufacturing.