Materials requested for project.
| Part | Price | Quantity | Notes | Status |
|---|---|---|---|---|
| 8x16x5 mm bearings | 20 | From Slider-crank mechanism | Ordered; Received | |
| Rotary shaft 200 mm x 8 mm | 2 | From Slider-crank mechanism | Ordered; Received | |
| 8 mm retention rings | 20 | From Slider-crank mechanism | Ordered; Received | |
| Aluminum stock (¼” x 1” x 48” bar stock for links) | $12.28 | 1 | 8975K596 (McMaster-Carr Part No.) | Ordered; Received |
| Aluminum plate stock (12” x 12” x ¼” plate stock) | $30.51 | 1 | 8975K142 (McMaster-Carr Part No.) | Ordered; Not Received |
| Rubber lining (1” x 18”) | $6.47 | 1 | 9023K82 (MacMaster-Carr Part No.) | Ordered; Received |
Design
Project Idea: Many wheelchair users experience difficulty traveling over curbs. Despite a number of assistive wheelchair technologies to address this problem, many of the solutions are bulky or expensive. Our team aims to design and develop a simple linkage-based device that will allow users to safely and quickly maneuver over curbs and gaps.
Concepts learned in class such as mechanical advantage will be implemented when designing this mechanism. Positional analysis of the wheelchair and curb scaling mechanism will be important for safety and efficiency reasons. The design will have a strong focus on mapping the location of the CG to prevent tipping as the mechanism will cause the wheelchair to tilt and translate. MATLAB will be used in the position and velocity analysis to aid in determining and finalizing the design of the mechanism.
Above are concept drawings for the mechanism. In reality, the curved pushbar will have two points of contact with the ground and will cause the wheelchair to not be perfectly level through the motion. Two cycles of the motion may be needed to get the wheelchair fully on the ledge.
An issue to consider for the project is the scale of the final prototype or presented class product. A life-size scale for a wheelchair presents difficulties in obtaining the required materials for construction and testing, and we may look into a reduced-size model for a prototype. Another issue is the separate mechanism for engaging and operating the curb scaling mechanism, which would be necessary for a complete, functioning attachment. The scope of the whole attachment may conflict with the class timeline, but because the two mechanisms are fairly independent, a single presentable mechanism with the conclusion of the class can be manageable. A final prototype might be the curb scaling mechanism, which would demonstrate translating a wheelchair or model from the ground onto an elevated platform.
Analysis
Manufacturing