Blog #4

 

    Over the work period of August 21- September 9, Team 8 has finished the fitment testing of the required parts as well as the system motion testing. The fitment assembly was completed by a combination of 3D printed components and cardboard made components as shown in the figures below.

Fig. 1 Seat and Seat Frame

Fig.2 Intermediate Connecting Part

As observed in the images above the H support and top intermediate connecting part were 3D printed, whereas the seat and seat frame were made out of card-board.  All components were made following the real measurements from the Solid works model. A final assembly is shown below, where each prototype part has been temporarily fixated to its corresponding location. Figure 3 shows the "neutral" sitting position of the Wheelchair Lifting Aid, and Figure 4 shows the seat with the fully extended linear actuator. 

Figure 3: Neutral Position of Wheelchair Lifting Aid

Figure 4: Final seat position of Wheelchair Lifting Aid

    Once the fitment testing was completed, it provided the team with some insights regarding the functionality and feasibility of the overall system design. Such insights pointed towards the minor modifications to be made prior to the final manufacturing of the system components. One of the most significant concerns to be considered was the asymmetry of the wheelchair frame. This lack of symmetry meant that the members of the H bottom support are to have individual measurements rather being proportional. Since individual measurements are necessary for each member of the H support, the team has decided to proceed with a nonpermanent fixture between the H support and wheelchair frame. This is to ensure further accommodations can be made to securely fix each H support member to the frame, as opposed to welding which was the team's original plan. The Team has received consultation from the Machinist at the University of Houston, and has proposed four (4) new clamps to adjoin the H support to the wheelchair frame. Such clamp can be seen in Figure 6 below, and Figure 7 illustrates how it can be used to adjoin the H member to the wheelchair frame. 

Figure 6: New Connecting Clamp

Figure 7: New Connection between H support and Wheelchair Frame

    Following, for the period of September 10 - 23, the team is to request pricings and quotes from vendors for the aluminum material needed. This aluminum material will be required to fabricate the intermediate connecting part, the H Support, and the seat base. Upon deciding on the most cost effective vendor, the team is expected to place the order for the material before September 15th. Next, the Team will obtain the necessary aftermarket components which are more readily available at hardware stores such as the plywood for the wheelchair seat, the cushioning for the seat, the hinges required to connect the seat, and the necessary bolts to affix the newly designed clamps with the H support. As the aluminum material is obtained, which is expected to be delivered prior to September 23rd, the Team will deliver the aluminum material to the machinist so the fabrication process can begin. 

    Over the next two weeks, the team is expected to experience several obstacles. Beginning with the newly added design changes (new clamps), the team is expecting to see a decrease in the quality of the structural integrity of the wheelchair frame. The team is anticipating that the junction of the clamps and H support will enhance the bending moment experienced upon activation of the linear actuator. As a solution, to further reduce the load experienced on the wheelchair frame during operation, the team is proposing installing caster wheels, which can be seen in Figure 8 below, underneath the H support to create a contact point with the floor surface. 

Figure 8: Proposed castor wheels 

Furthermore, the team is currently reviewing the validation plan of the project. It has been brought to the Team's attention that a survey conducted across multiple caregivers will be very time consuming using a digital angle protractor to manually record the caregivers angle of inclination. Therefore to save time during the validation process, the Team is currently looking for a digital angle protector with data logging capabilities.