04.3 - Design Process
During the design process, we began by identifying a small-scale, solvable problem. We chose to design a low-speed pitching machine because it addresses a relatively untapped market segment. When children first begin playing baseball, they typically start with tee ball, where the ball is stationary and easier to hit. At the other end of the spectrum, high school players often train with high-speed flywheel pitching machines, including advanced variants capable of throwing breaking pitches such as curveballs or sliders. Our design targets the transitional stage between tee ball and high-speed pitching machines, where children usually learn to hit pitched balls by having parents or coaches lob pitches toward them at low speeds.
A key design goal was to minimize the number of user controls and instead rely on the mechanical design to consistently produce accurate, repeatable pitches. To begin, we created a baseline sketch in SolidWorks and manually adjusted dimensions until the overall motion appeared realistic. This initial sketch was used to visualize the frame, define the intended motion, and understand how the system could be physically realized. Developing this sketch provided a foundational understanding of the structure and constraints required to maintain mechanical integrity of the mechanism.
Figure 2: Illustration of the Sketch Movement
Next, we conducted a kinematic analysis by iteratively adjusting parametric dimensions to achieve a target tip velocity. Our goal was a tip velocity of approximately 5 m/s, suitable for beginner-level batting practice. Once this target was met, we transitioned from conceptual sketches to fully defined solid bodies in SolidWorks. An early CAD draft of this stage is shown below. This model illustrates the general attachment mechanisms and spatial layout of components, allowing us to identify potential interference and mechanical conflicts. While functional, this version was not intended to be a final design.
From this point forward, the design evolved primarily through iterative CAD refinement. We applied straightforward and practical design principles to standardize components and simplify manufacturing and assembly. Shaft diameters were limited to 6 mm and 8 mm, as these sizes were readily available for the course. Additionally, we introduced modular side mounting plates made from laser-cut acrylic to simplify joint mounting and improve alignment with the base. Throughout this stage, we prioritized simplicity, only including components that were necessary for function and reliability.
After finalizing component placement and geometry, we arrived at a complete prototype design. We then 3D-printed the prototype components and assembled them for preliminary testing. Following initial assembly, we added mounting points for both the DC motor and the servo motor, as well as additional structural supports, to ensure stability during operation and motion.