Uniwheel’s aim was to be the first to market with a design that was thoroughly thought through. That target was met at the end of 2015, when the company launched its first consumer product, just seven months from first concept. The use of NXTM software from Siemens PLM Software was fundamental to the success and speed of the entire development project.
Balancing form and function on one wheel
From first concept, the design team began using NX to create basic 3D models of elements such as the external styling of the plastic case, which has integrated lighting; the metal for the pedals and motor; and details such as the grip on the surface of the pedals. The main challenge was to package the electronics and software, the removable battery packs, the motor and the wheel housing. Allocating appropriate spaces for the wiring looms was critical. With an emphasis clearly on the ergonomics of the main casing, 3D curves had a big role to play.
With safety a key focus throughout the design process, a range of sensors had
to be incorporated into various parts such as the pedals and the handle. The sensors allow the motor to respond automatically when a foot is put on or taken off a pedal, or when the device is lifted off the ground. There is also a cut-off point to prevent the motor being taken to its limit.
Much thought went into designing the wheel and the tyre, then refining tyre pressure in order to create more surface contact with the ground to provide stability and assist with battery life. In addition, the team used NX to design a specific tread pattern that would allow water to run off quickly for better grip.
Nearly 400 different components and 25 pieces of tooling were created and assessed within NX to ensure that there were no interference or clash problems. In some cases 3D printing was used to create rapid prototypes, particularly for the bi-directional lights, which alter according to the orientation of the machine, adjust to levels of daylight and grow brighter when the rider is slowing down.
TritanTM copolyester, a tough,
collision-resistant plastic, was chosen for the case, and this was overmoulded with silicone rubber to absorb impact. Engineers devised a test rig for conducting physical wear-and-tear testing to replicate the process of the unicycle being knocked about in daily use.
Steve Godden, a Uniwheel designer explains how the main case is very complex, yet the only issues found in testing were cosmetic, and the designers could easily see and adjust the detail of the surfaces. Using NX resulted in superb clarity and precision.
Predictability alleviates pressure
With several international suppliers lined up to do tooling, it was imperative that Uniwheel’s designers could convey the design intent. The use of NX and the direct transfer of computer-aided design (CAD) enabled clear and constructive discussion about the tooling and manufacturing process. Only one tooling trial was conducted, as part of the process of refining the lights.
Using NX to optimise the way in which all the design elements come together, the Uniwheel team was able to reduce overall weight by more than 0.91kg, taking the device to less than 11kg, an
achievement that led to the casing for the motor being patented. The team was also able to hide screw holes in the main case while ensuring complete ease of assembly. It takes just one hour to put together a finished product in Uniwheel’s London research and development unit. Right on time, the first fully finished electric unicycles were launched in December 2015, only seven months from the original idea.
For Uniwheel’s team of designers, the reliability and stability of NX was critical. Mark Kennell observed from past experience that NX is robust and utterly predictable, and with the ambitious timescales was exactly what was needed.
The first UK electric wheel
With a 16in wheel and a 1,500W motor that stops automatically when the user steps off, the Uniwheel has the flexibility to deal with bumps and curves on the ground, but being at ease on a single wheel still takes a little practice. “The hardest thing is to ride at less than seven or eight miles per hour, when you can’t rely on momentum for side-to-side balance,” says Steve
Milton, director and chief executive of Uniwheel. “However, we see the learning curve as cool and intrinsic to the appeal for potential customers.”
Designed and assembled in the UK, the Uniwheel is streamlined to the lower leg and delivers up to 90 minutes of ride time. It can reach speeds of 12mph and has a range up to nine miles, yet it takes just one hour to charge fully. The controls are easy to negotiate and customisation is enabled through the colourful bumpers, which can be replaced if they get scratched from regular use. The pedals can be exchanged as well.
Milton reflects on the company’s first year: “It is vital to us that NX is so reliable. This was a startup, with an ambitious target and a young team of designers who had not taken a product from design to manufacture before, yet I knew that NX would take us from visualising on a piece of paper to the finished product.”
Tapping into growing demand for assisted personal transportation, Uniwheel is already considering future developments. “As performance-to-weight is of critical concern to us, we are planning to expand our capability using NX for CAE,” says Milton.