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Protean Electric develops advanced electric-drive corner module concept for next-generation urban mobility pods: Protean360+

Protean Electric has developed a new corner module concept that integrates advanced powertrain, steering and suspension technologies within a single product. The module, called Protean360+, is thought to be the first of its kind to be developed for commercial applications that offers a limitless 360-degree steering capability.

This is combined with innovative suspension, pneumatic ride-height control and a highly efficient and powerful ProteanDrive in-wheel electric motor.

Protean360+_annotated graphic

Protean Electric is developing the Protean360+ module for next-generation urban transport vehicles tasked with smoothly and efficiently moving people and goods around busy conurbations. The module’s compact packaging will allow for an entirely flat vehicle interior floor and sufficient lateral access to offer wheelchair ingress and egress via front, rear and side doors, bringing better mobility solutions for all.

This also means the vehicle can park front-, rear-, or side-on to the kerb, and occupants can disembark straight onto the pavement without having to step into the road.

The exceptional maneuverability enabled by the 360-degree steering system will allow for exceptional versatility on busy urban streets, and parking in tight spaces with absolute kerb-side precision. Once stationary, the pneumatic ride height control of Protean360+ will enable the vehicle to kneel, dropping the vehicle entry-point to kerb level. This will afford stepless and virtually gapless ingress and egress for heavy or cumbersome loads or for passengers with impaired mobility.

Transport-as-a-Service urban mobility is gaining momentum, and with it the need for a new class of urban transport vehicles. Whether shared or private, for passengers or goods deliveries, human-driven or autonomous, these new vehicles will require new technologies to be fit for purpose. The Protean360+ corner module was borne from our team’s innovative thinking about how to meet the requirements for these next-generation urban vehicles.

The Protean360+ corner module intelligently combines cutting-edge, production-ready technologies. Its unrivaled capabilities significantly advance the effectiveness of the urban transport vehicle concept, and we are already in discussion with prospective customers wishing to apply the corner module in their future vehicles.

—KY Chan, CEO of Protean Electric

Limitless 360-degree steering. The capability for each wheel to be steered continuously through 360 degrees without limitation will give vehicles an exceptional level of maneuverability.

Autonomous vehicles will be required to negotiate complex combinations of fixed street furniture as well as unexpected obstacles in their path. The ultimate maneuverability delivered by independent four-wheel limitless steering means the vehicle will not need to stop-steer-move when performing even the most complicated maneuvers. Protean 360+ will help to minimize the risk of the vehicle encountering a situation that it is unable to smoothly and safely negotiate. As a result, journeys will be less susceptible to disruption or delay to passengers and other road users, helping to contribute to more predictable traffic flows and less congestion.

Because the corner modules will enable the vehicle to spin through 360 degrees within its own footprint, it will be able to make uninterrupted progress along narrow urban streets and around tight corners at junctions and in parking lots and loading bays, for example. And, crucially, it will allow ultimate precision in maneuverability for the final metre when approaching the kerb to park up.

The 360-degree steering capability is made possible by a patent-pending rotating interface that sits above the corner module’s main arm. The top of the rotating interface is fixed to the vehicle; the lower interface is fixed to the module arm.

The electric steering unit (by-wire controlled) is located above the interface, so that the axis points to the bottom of the wheel.

From the lower rotational interface, control cables for the motor, hydraulics, and pneumatic ride height controls are channelled down the module arm and are connected to a second static interface within the hub and into the wheel motor unit. As the arm module rotates through 360 degrees, the full component set rotates with it. As a result, the connections and cables are not twisted or stressed.

Novel twin-knuckle suspension for compactness. The primary challenge for the suspension system was the compact packaging required to ensure that the system takes up the minimum internal space, facilitating improved access for people with reduced mobility or greater cargo capacity. To achieve this compactness, the development team conceived a novel multi-link design with an additional lower wishbone pivot.

The patent-pending quad-pivot double-wishbone spider movement enables high-strength force transfer with both compact packaging and full-range suspension travel. This novel suspension packaging allows optimum geometry and additional articulation in the lower suspension arm in order to achieve the desired kinematics, while retaining the all-important package compactness. It also allows the suspension system to exhibit identical behaviour and performance in all directions of travel.

As a result, a single common module design is optimized for all four corners of the vehicle, negating the need for left and right or front and rear versions, thereby reducing development and production costs.

Pneumatic ride height enables vehicle kneeling. A critical target for the development team was to provide the capability for vehicles to ‘kneel’, in order that stepless curb-to-vehicle access can provide easy entry and egress for passengers with reduced mobility, wheelchair users, pushchairs, and for loading goods.

A pneumatic ride-height system will enable the vehicle height to be raised or lowered. The pneumatic reservoir and compressor are shared with other systems in the vehicle and provide independent control of suspension air at each corner to precisely control the level of the vehicle floor.

Fully integrated in-wheel motor. Electric propulsion is provided by the ProteanDrive in-wheel motor, a highly integrated patented design that provides maximum efficiency and flexibility and that combines motor and inverter within a single drive unit. It is significantly more efficient than alternatives, such as e-axle solutions, thanks to the elimination of driveline losses.

In-wheel motors also offer greater dynamic control of the overall power and torque delivery. They can apply positive or negative torque within milliseconds, meaning improved performance of ESC, ABS and traction control systems, which benefit safety, stability and stopping distances (typically 7% shorter, according to an independent study). Furthermore, there is a greater level of redundancy, especially in four-motor setups, as torque load can be transferred if problems occur in any one motor.

ProteanDrive constitutes a permanent-magnet synchronous motor with an integrated inverter and a dedicated liquid cooling circuit, all tightly packaged within the wheel rim. A friction brake disc and caliper are packaged in the wheel with the ProteanDrive motor, complementing its regenerative braking capability.

The rotor of the electric motor connects directly to the hub, delivering torque from the motor to the wheel and removing losses in power transfer. The direct drive configuration is reflected in the high-torque, low-speed design of the ProteanDrive motor. The motor features an outer rotor to maximise torque; this outer rotor configuration allows the rare earth-magnets to be surface-mounted without retention features that would otherwise compromise performance. Each ProteanDrive Pd18 motor (to fit an 18-inch wheel) develops 1250 N·m (922 lb-ft) peak torque and 80 kW (107 hp) peak power.


  • Satoshi Murata (2012) “Innovation by in-wheel-motor drive unit,” International Journal of Vehicle Mechanics and Mobility, Volume 50, Issue 6, pp 807-830 doi: 10.1080/00423114.2012.666354



Ideal improved access e-vehicle for down town traffic with narrow streets and difficult parking.

Steering/drive train assemblies could be mass produced at much lower cost in large centralized factories.

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