For this TEK Engineering for Kids project, we have been assigned with the task of creating a wheelchair for someone in need of various different aspects that are not on a normal wheelchair. For example, we are planning on creating an automatic/electric wheelchair that will satisfy the needs of the consumer such as off-roading capabilities, smoother overall moving on various different daily route terrains, etc. We plan to make this wheelchair accessible to the user in versatility and overall effectiveness.
For our background research, we examined a range of adaptive wheelchair designs and modifications. This included analyzing existing adaptive wheelchair models with a focus on safety and user comfort. After evaluating these considerations, we determined that utilizing two prefabricated electric bicycles would be the most time-efficient approach. While this method increases overall project costs, the significant savings in time justify the additional expense.
The Chariot is a design developed by the YouTuber JerryRigEverything. Compared to our other concept designs, this approach offers several advantages. While it provides many of the same capabilities as The Rig, it requires significantly fewer materials and less fabrication time. These benefits make the Chariot the most practical and efficient choice among the concepts we evaluated.
The Rig was our original concept but has proven difficult to see a path to create a design with similar functionality to the limitations we currently have. The Measurements of the design make it cumbersome to deal with, it can be overly heavy and finding parts large enough to accurately simulate its performance has proven difficult and costly in both time and funding the wheels are an example of this.
Conceptually, it seems very good but constructing this in any reasonable manner could take much longer than we have time for, waiting for materials such as the motor, wheels, a mountable seat, and possibly fixing any issues that may arise. Logistically this concept seems unreachable based on the time frames need to create something of similar stature.
The Grit Freedom Chair was a concept we turned to once we realized the importance of keeping the chair design simple, it can help the recipient manipulate and get better functionality from the chair even when issues may occur, the light weight bike wheels and open frame allow for easier repairs in an emergency, a lack of motor on this chair is an issue, but one can be implemented, allowing for manual or motorized movement capabilities, the sleeker design allows for better maneuverability in tighter areas or populated areas, giving a larger range of travel opportunities. The grit had more uses and less logistical issues.
We have decided to proceed with the Chariot design. This concept has the best cost-to-time efficiency without losing any of the core ideas for the design.
We have decided to proceed with the Chariot design. This concept involves combining two electric bicycles by mounting their frames together and installing a central seat between them.
We will be combining two electric bicycles by mounting their frames together and installing a central seat between them. The chain and gear hub assemblies will be removed to provide adequate space for the seat mounting, as these components will not be utilized in the final configuration. We will be constructing the center seat by welding round tubing together. As far as connecting the turning radii together, we will be using something called Ackermann Steering. This will create 2 separate joints from the front wheels so that they can be connected together using a singular rod. This will, overall, allow us to ultimately have each bike move and turn in unison. Along with this, we also have a plan to combine each of the bike’s braking mechanisms into one mechanism to have an easier overall braking experience for the user.
For this engineering analysis, we developed a 3D model of our seat assembly in SolidWorks and conducted a static simulation applying a 700 lbf load to evaluate the structural integrity of the design. The material used for the analysis was AISI 316 stainless steel, selected for its high yield strength and corrosion resistance. The model was meshed using a high-quality, curvature-based solid mesh with over 16,000 elements to ensure accurate results.
The simulation results showed a maximum von Mises stress of approximately 1.27 × 10⁸ N/m², which is well below the material’s yield strength, indicating that the seat can safely withstand the applied load. The resultant displacement ranged from 6.44 mm to 6.47 mm, suggesting minimal deflection under the 700 lbf load. These results confirm that the seat structure is sufficiently rigid for its intended application.
For this engineering analysis, we dove deeper into the steering mechanism on our designed wheelchair. Within this analysis, we delt with an Ackermann steering joint’s geometry. We then modeled it in Solidworks, and this was the basis of our analysis.
We made the material of our “teardrop” edge shapes to be Cast Alloy Steel and the other two materials were Zinc Plated Carbon Steel and Low Carbon Steel. After applying these materials, we applied torques of 150 N-m to the cylinders within the teardrop shape. After these torques were applied, we had found that the beam will bend at roughly 2 mm at the extremes.
The process began with ordering the bikes first, since limited measurement information prevented us from selecting additional components early on. Once the bikes arrived, we tested them and removed unnecessary parts such as the pedals, chain, kickstands, seats, and throttle assemblies. With accurate measurements available, we were then able to order the remaining components needed for the project. After those parts arrived, we began assembly by welding a connecting bar through the pedal openings to join the two frames. The most challenging part of this step was ensuring the bikes remained level while welding both sides. After securing the connection, we welded the main frame structure and additional support bars to provide the necessary strength and stability. Throughout the build, we refined the Ackermann steering system and incorporated it once all components were finalized. We also added sheet metal to prevent snagging during entry and exit. Afterward, we rewired the controls to allow a single throttle input to operate the entire system. The project concluded with painting the bikes black and mounting the swivel mechanism and seat to the frame.
The project was tested continuously throughout the build to ensure that each modification performed as intended. For final testing, we rode the bike around campus on a variety of surfaces to evaluate overall performance. This allowed us to confirm that the throttle response, Ackermann steering system, and frame structure were all functioning correctly and safely under real operating conditions.
Battery Safety
Do not overcharge the batteries; unplug the charger once charging is complete to maintain battery health.
Charge only with the approved charger and in a dry, ventilated area.
Inspect battery cables and connectors regularly for damage or overheating.
Pre-Ride Safety Checks
Ensure the swivel mechanism is fully locked before riding.
Verify that the throttle and brakes respond correctly before each use.
Check tire pressure and look for visible tire damage.
Operating Safety
Operate at a safe speed, especially on narrow paths, rough terrain, or around pedestrians.
Avoid sudden acceleration or sharp turns that could reduce stability.
Keep hands, clothing, and loose items away from moving parts.
Terrain Guidelines
Use caution on uneven or sloped surfaces; keep speeds low.
Avoid deep potholes, loose gravel, and wet or slippery ground when possible.
Do not attempt to climb hills steeper than what the motors can safely handle.
Rider Position & Stability
Ensure the rider is seated properly with feet inside the designated foot area.
Do not lean excessively to one side while in motion.
Do not exceed the recommended weight capacity of the wheelchair.
This project was incredibly rewarding, as it allowed us to expand the mobility options available to a fellow student. Throughout the process, we faced numerous challenges that required problem-solving, creativity, and teamwork. Each obstacle—from design limitations to mechanical and electrical issues—pushed us to think critically and adapt our approach.
In the end, we were able to build a device that meaningfully enhances our client’s independence and gives him opportunities that a standard wheelchair could not provide. Seeing the final product come together, and knowing it can improve his daily life, made the entire effort worthwhile and reinforced the value of engineering for real-world impact.
