ME Capstone - All Terrain Cart System (ATCS)
Overview
There is currently a gap in the product design of motorized carts that sits between “professional-grade indoor” and “consumer-grade outdoor”. Therefore, there is a lack of products in the market representing a low-cost professional-grade cart that can be used for both indoor and outdoor applications. The market has a multitude of professional-grade high-end carts that touch most needs faced by factories and distribution centers. On the other hand, average consumers have been reached by cheaper carts designed for outdoor use transporting lighter loads.
Our Capstone team noticed this market gap and throughout 3 COVID-struck months in the summer of 2020 designed an All-Terrain Cart System that would adress this market. The design covered a multitude of considerations including battery size, powertrain, frame, brakes, and even a feature to allow for extendabilty.
Design Focus
Deciding where in the market the ATCS was going to be designed for was the first step in the design process, but executing a design is more complicated than simply finding a place for it in the market. In the beginning stages of bringing our initial idea to life, it was important to figure out how everything was going to be connected and provide a general design outline. During this process, some technical problems were revealed such as how the cart would be powered and controlled. Because the cart is going to be controlled by an imperfect controller (the human), there will need to be safety features preventing the cart from causing property damage or personal injury. It was also important to address the battery that was on board, and the various issues that are associated with it. The battery needed a waterproof space where it could safely exist, while maintaining full functionality. The ports in which the battery feeds also needed to be waterproof to enhance product quality.
Design Goals
Much of the technical problems could not be solved independently as the solutions to one problem would affect another, and so on until a web of trade-offs was clear. Considering the trade-offs for various design alternatives, the team wanted to make sure that every design decision addressed the target market by developing design goals to reach this market. Overall, the ATCS was designed as a professional-grade cart with a competitive price and functionality to also reach the needs of a high-end consumer. Fundamentally, the ATCS should be able to move a load or serve as a portable workstation, easing the job of the user. The structure should allow for the ATCS to be used in both indoor and outdoor applications while meeting waterproof and shock standards. Battery life should be the best it can be, though this will be more of a price issue than anything else. The base of the All-Terrain Cart System should have attachment points to allow for additional features, creating a modular aspect to the cart and opening the possibility of third-party design for attachments serving specific purposes. It should be easy to control the ATCS, and there should be safeguards in place to detect and prevent accidents.
Addressing the Design Goals
Since the small business owner or higher-end consumer is not going to have the kind of money that corporations running manufacturing facilities and distribution warehouses have, it was important to minimize the cost of the ATCS. A cost in the range of $1500-$2500 would hit the target market discussed previously. The fundamental function of the cart is to aid in moving heavy loads or act as a portable workstation. To provide motive power to the cart and meet this fundamental function, an electric motor was chosen. Additionally, a gearbox was designed to provide an increase in power output from the motor. Because the cart is mobile, a battery was fit on board to provide electric power to the motor as well as additional components. In addition to the motor, the battery will also support a hub holding various charging port designed into the side of the cart, as well as a lighting system to assist the user in situations of poor lighting. To prevent the cart's design from moving outside of the target market, a simple steering system was chosen in which the front wheels are attached directly to the handle. The speed control, as well as the brake control, was designed onto the handle for simple manipulation of the cart’s movement.
Performance Metrics
There are a few specifications that the team is demanding from the cart, no matter the cost. These are the attributes that define the cart and set it in a class of its own. The first and arguably the most important performance metric is the ability for the cart to support a payload of at least 300kg. This will allow most items that would fit in or on the cart, to be moved by the cart. Additionally, it is important for the cart to obtain a useful amount of operation time between battery charges, so the user's work does not have to be interrupted by the cart's dead battery. The ATCS should allow for 1.5 hours of continuous operation between charges so the user can comfortably achieve their work before needing to charge the cart. The speed of the cart should be the most comfortable speed to operate, which for the average user would be the walking speed of an adult. To meet this requirement, the speed of the cart should be at least 3mph.
Summary & Future Steps
The team took an initial concept design for a motorized cart and built an incredibly well thought-out, highly capable machine. The innovative design of the axle system combined with the sophisticated electrical technology make the All-Terrain Cart System the ultimate weapon for any environment. If the development of the ATCS were to be taken further, the future steps would include developing a physical model as, up until now, only virtual models have been produced with the aid of SolidWorks. Next, the prototype would be pushed to market for testing and the iterative cycle of making changes and taking feedback would begin.