12.3 Design Process
Initial Design Ideas
When brainstorming for the project, we decided to implement a linkage system that would slide on rods via linear bearings to create a smooth, controlled motion for the lifting aspect. For the tilting, we would connect another 2-bar system on a platform as shown in Figure 1. All of this would be on an L-shaped stand.
After kinematic and weight analysis, it was found that this iteration would not be feasible as the weight of a laptop would bend the top platform downward and create a forward tilt. This would not achieve our goals and would be difficult to create realistically when including motors and other objects.
After more brainstorming as well as trial and error, the next, and final, design iteration resembles what is seen in Figure 2. This has 4 linkage systems driven by a motor that drives gears for each side (per 2 linkage systems). This guarantees that there is even motion per 3-bar system for lifting while allowing us to also control the tilt of the stand. We kept the rods where the links would slide to ensure stability and linear motion.
There was a lot of difficulty in regards to achieving tilt for the mechanism. After much trial and error, it could not be concluded within the time frame for how to adhere to weight limitations when implementing a separate system for tilt. Therefore, for the final design, it was finalized that we would control one side at a time so it could tilt and have a separate button for lifting versus tilt.
Utilizing CAD modeling, we verified that our linkage lengths would work properly and display the intended motion. The assembly moves smoothly in an upward and downward motion. Using this, we then moved on to assembling the final prototype as we had now verified the most vital part of the design.
Prototypes and Iterations
To test link lengths and motion of the laptop stand, scrap wood and cardboard was used to produce a prototype. While this cannot hold the weight of an IPad whatsoever, it displays the necessary motion that is needed to create a successful final prototype utilizing our intended materials. This prototype displays motion of one of the sides and due to symmetry, this would ensure that the other side works as well.
While building the final prototype, it was decided that bevel gears would be utilized to make the motor rotation drive the rod rotation that runs the system since they would be perpendicular to one another and ensure even motion. This addition ensures that our system would look cleaner and the motion of one side is driven by a singular shaft.
Final Prototype
For the final prototype created for demo day, the final design idea was utilized while adding bevel gears and geometrically constraining link motion in order to guarantee that it could rotate without interruption. To create a successful design, the base plate needed to be large enough to support the 4 link systems with 180 degrees of motion as well as the motors. The laptop plate would be supported by 3D printed parts that would go on the vertical slider mechanism. For the entire system the links, base plate, and laptop plate was made of wood, supports 3D printed, and rods to drive the motion and allow for linear motion. Below are the pictures of the final prototype.