Distributed Drive and Brake System

The Distributed Drive and Brake System represents a crucial development milestone in modern intelligent electric vehicle (EV) chassis technology. Unlike conventional vehicles that rely on a single central engine or electric motor to mechanically distribute output to the wheels via driveshafts and differentials, alongside a centralised brake master cylinder actuating individual wheel calipers, a distributed drive and brake system directly integrates or positions drive and braking units at each wheel (via in-wheel or near-wheel motors), or precisely controls individual wheel brake actuators independently (such as through Electro-Hydraulic Braking [EHB] or Electro-Mechanical Braking [EMB]). This "four-wheel independent control" architecture delivers unprecedented dynamic response speeds and exceptional packaging freedom.

Core Technical Architecture and Working Principles

The technical architecture of a distributed drive and brake system relies primarily on drive-by-wire technology and multi-motor distributed coordinated control: 

Distributed Drive and Wheel-End Independent Torque Vectoring (Distributed Drive and Independent Torque Vectoring): 

Under a distributed drive architecture, two or four wheels are powered by dedicated drive motors (such as in-wheel motors housed directly inside the wheel rims, or near-wheel motors driving through half-shafts). The Vehicle Control Unit (VCU) and distributed domain controllers can independently apply positive drive torque or reverse regenerative braking torque to each individual wheel with millisecond-level precision. Free from mechanical differential lag, this Torque Vectoring Control (TVC) actively channels more drive torque to the outer wheels or applies braking force to the inner wheels during high-speed cornering or across split-friction surfaces (such as unilateral ice or snow). This generates an optimal yaw moment, significantly raising the vehicle’s handling limits and cornering line-tracing capabilities.

By-Wire Distributed Braking and Redundant Actuators (By-Wire Distributed Braking and Redundant Actuators):

To complement the powertrain, distributed braking systems typically adopt Electro-Hydraulic Braking (EHB) or Electro-Mechanical Braking (EMB). Instead of relying on conventional vacuum boosters and intricate hydraulic piping, each wheel's brake caliper is actuated independently and precisely by a dedicated electronic control unit alongside an electric motor or high-pressure solenoid valves. The system executes individual wheel pressure build-up, reduction, and retention in milliseconds. This not only shortens brake response times, but also integrates seamlessly with the distributed drive system's regenerative braking, achieving an optimal balance between powertrain efficiency and braking performance. 

Safety Guidelines and Physical Constraints 

Strictly Prohibit High-Speed Driving Relying on ADAS or Dynamic Stability Control When Core Sensors (e.g., Wheel Speed Sensors, Steering Angle Sensors, IMUs) or By-Wire Communication Buses Fail (Prohibiting High-Speed Driving with Failed Distributed Control Sensors or Buses): 

Precise control in distributed systems relies heavily on real-time feedback from the vehicle's sensor suite regarding road conditions and individual wheel dynamics. Never activate advanced driver assistance systems when faults are present. If a wheel speed sensor fails or bus communication experiences latency, the distributed controller will receive corrupted input data and potentially issue incorrect drive or braking commands to specific wheels, triggering sudden unilateral wheel lock-ups or uncontrolled acceleration. 

Never Overlook the Impact of Substantially Increased Unsprung Mass from In-Wheel or Near-Wheel Motors on Suspension Response, Ride Compliance, and Impact Harshness over Rough Roads (Prohibiting Ignoring Increased Unsprung Mass Dynamics): 

Mounting heavy electric motors directly inside the wheel assemblies (in-wheel motors) significantly increases the vehicle's unsprung mass. Suspension tuning must never be neglected in the pursuit of pure in-wheel drive setups. Higher unsprung mass compromises tyre road-holding capability and causes wheel hop over undulating surfaces and unpaved gravel roads. This impairs ride comfort while subjecting the structural integrity of the suspension and damper valving to severe impact loads.