From left: Tsuyoshi Uchino, Yoshihiro Hirata (Chassis Development Group, Mechanical Engineering Dept.)
|The impact from driving over bumpy, uneven surfaces is an unpleasant experience for the user. Especially when riding for an extended period of time, it may cause mental and physical fatigue. Proper suspension is necessary to eliminate such discomfort and improve stability. The Model Ci suspension connects the wheel and the main body, absorbing impact and vibration from uneven surfaces through the spring, stabilizing the device. Additionally, by carefully engineering the material and design of the frame to support the main body, it further stabilizes the ride. In the process of creating the Model Ci to deliver a comfortable and smooth ride, there was quite a bit of trial and error. Here’s what the Model Ci frame and suspension designers had to say about the process:|
Swingarm suspension to reduce vibration and absorb shock
“We added suspension to the front wheels, suppressing the vibration and impact transmitted from the omni-wheel to the seat. There were unique challenges developing the suspension for a personal electric vehicle. EV suspension compared to car suspension has more shock to reduce. Mobility devices have to reduce both the vibration coming from the road surface and the shock at the time of getting over a bump or curb. We adopted a form of suspension used for motorcycles, known as a swingarm. Swingarm suspension has high range of mobility, absorbing vibration and impact from downward and lateral directions. By using the swingarm suspension for WHILL omni-wheels, it reduces both vibrations from the road surface and large shocks while driving over uneven surfaces.”
Using the bending of the iron frame on the rear wheel
“Initially, we were planning to install suspension on the rear wheels, but there were some challenges. When adding in space for suspension, the surroundings of the rear wheel became bulky, and the stylish look of the Model Ci was compromised. Moreover, rear wheel suspension added too much weight, which would have decreased the Model Ci’s portability. Focusing on the silhouette of the main body and keeping it lightweight, we envisioned a structure that will let the frame absorb shock, allowing it to run comfortably even without rear suspension.
“Model Ci is primarily made of lightweight aluminum. The parts supporting the left and right rear wheels and main body are made of iron. The iron components help with shock absorption, reducing impact from the rear wheels to the main body and seat. We repeatedly tested the use of these iron parts, aiming for a design that was lightweight and sleek, while helping to minimize vibrations.”
Creating a comfortable ride
Although it is difficult to completely reduce vibrations, our main goal is to create a comfortable driving experience for the user. We will continue to improve upon the current technology and make the most comfortable ride possible.
|Yoshihiro Hirata, Group Leader
Graduated from Department of Mechanical Engineering, Nihon University School of Production Engineering. After joining Akebono Brake Industry in car design for brakes, joined WHILL in 2014. As a group leader of the Chassis Development Group, Mechanical Engineering Dept., engaged in the design of WHILL’s chassis (whole body structure) part.
Tsuyoshi Uchino, Mechanical Engineer
Graduated from Mechanical Engineering Department, Faculty of Engineering, Kagoshima University. Honda joined WHILL in 2016. As Chassis Development Group Mechanical Engineer, Mechanical Engineering Dept., engaged in designing chassis part of WHILL.