Zonal architectures in off-highway vehicles
KEY TAKEAWAYS:
- Zonal architectures help off-highway vehicle design scale more efficiently
- Early system-level partitioning ensures mission success
- The rising complexity of off-highway systems is mitigated through a zonal approach
Electrification and automation are increasing in off-highway vehicles such as mining trucks, agricultural machines and mobile robots. In established architectures, every feature has an electronic control unit (ECU) and its associated harness branch. But just as in the mainstream automotive industry, this becomes difficult to scale with power demand, connectivity and autonomy requirements growing.
Zonal and centralized architectural approaches provide a practical framework for reducing harness complexity, optimizing compute resources and preparing platforms for higher levels of software control.
System architects can apply these same concepts to mining vehicles, agricultural equipment and service robots. The emphasis is on system partitioning, 48 V and mixed-voltage power distribution, backbone networking, safety partitioning and connector strategy.
Reducing harness complexity by moving from distributed ECUs to zonal control
Many off-highway platforms were built incrementally. A steering function, telematics feature, boom controller or spray subsystem was often added as a separate ECU with its own power feed and network connection. Over time, that approach creates a vehicle with many dispersed ECUs, long harness runs and a central power distribution point that becomes difficult to expand or diagnose.
A zonal architecture reorganizes the machine around physical areas instead of individual functions. The vehicle is split into zones such as cab, front chassis, rear chassis, left implement and right implement. Each zone uses a zone control unit, or ZCU, to aggregate local I/O, distribute power and connect local devices to the rest of the machine through a smaller number of backbone links.
In a centralized or hybrid architecture, high-level applications move toward a central compute node or domain controller, while local sensing and actuation stay close to the machine hardware inside each zone. This arrangement reduces the number of long point-to-point harness runs and creates clearer boundaries between local control, backbone communications and central compute.
Business and technical drivers for zonal architectures
The case for zonal and centralized platforms is particularly strong in off-highway equipment where environmental and application demands are severe. External zones may see mud, dust, vibration, wash-down, fertilizers, hydraulic fluids and large temperature swings, all of which influence controller placement, connector choice and cable routing.
These platforms also tend to carry mixed-voltage electrical systems. A machine may combine a traction battery or generator, increasingly include a 48 V distribution rail, and have legacy 12 V or 24 V loads that still need to be supported. In parallel, automation functions such as perception, coordinated motion and remote supervision increase the amount of data that must move across the vehicle and raise the importance of deterministic networking (e.g., TSN-enabled Ethernet or equivalent real-time communication schemes).
For system architects, the result is a need to partition the machine more deliberately. The architecture must support power conversion, data transport, safety functions and serviceability as a single system rather than as a collection of standalone ECUs.
How 48 V backbones enable distributed power conversion in zonal architectures
A 48 V backbone is attractive because it reduces copper losses and wire mass compared with an equivalent 12 V distribution scheme, especially as auxiliary loads rise into the multi-kilowatt range. This is one reason suppliers increasingly describe 48 V as a key enabler for zonal power distribution and distributed conversion near the load.
At system level, a typical architecture begins with a high-voltage traction pack, generator or existing low-voltage source. A central or distributed conversion stage then produces a protected 48 V bus, and that bus is routed to each ZCU over high-current feeders. Each ZCU can then create local 12 V or 24 V rails for legacy loads, while keeping short power runs to actuators, lights, valves and nearby electronics.
This arrangement gives the architect several useful choices. Critical zones can receive redundant 48 V feeds. Isolation boundaries can be placed between traction power, 48 V distribution and low-voltage local loads. Local power switching can be integrated into the ZCU so that current monitoring and fault reporting happen close to the affected loads.
Vicor publishes material describing 48 V zonal power distribution using modular conversion stages from high voltage to 48 V and then from 48 V to lower rails. STMicroelectronics also provides 12 V and 48 V reference material that can help define the major conversion blocks early in the architecture phase.
A zonal power architecture works best when paired with an equally deliberate data architecture. In practice, that usually means a high-bandwidth Ethernet backbone connecting central compute, ZCUs and gateways, with shorter local networks inside each zone.
This layered approach allows the architect to assign traffic by function. Time-sensitive or high-bandwidth data such as perception streams, synchronized control messages and central diagnostics can use the backbone. Local actuator and sensor traffic can remain inside the zone, often on CAN or CAN FD, with translation handled by the ZCU.
Suppliers in the industry, including NXP and onsemi, have published reference material around zonal controllers, Ethernet switching and the transition toward software-defined vehicle architectures. Those materials are automotive in origin, but the partitioning logic maps well to large agricultural machines, mining equipment and service robots where the physical spread of sensors and actuators makes zonal aggregation attractive.
For non-automotive platforms, segmentation is not only a matter of bandwidth. It also supports fault containment and serviceability. A fault in an implement harness should not bring down unrelated chassis functions, and the architecture should make it clear which controller owns each local network and load group.
Central compute and ZCU partitioning
A central compute node, typically MPU- or SoC-based, often with GPU/NPU acceleration for perception workloads, is usually the right place for applications that benefit from consolidated processing or shared data. Examples include autonomy, path planning, perception fusion, user interfaces, fleet connectivity and machine-wide diagnostics. By contrast, ZCUs are typically responsible for I/O aggregation, power distribution supervision and local gateway functions, and may also host deterministic local control loops depending on system design.
This separation helps system architects make cleaner allocation decisions. Functions that must continue operating – even when high-level applications are degraded – can remain local to a ZCU or safety controller. Functions that depend on machine-wide context or substantial compute can be centralized.
A hybrid pattern is often the most realistic migration path. Existing ECUs can remain as local smart nodes within a zone while their power and communications are absorbed into the new zonal structure. That allows a staged transition rather than a disruptive clean-sheet redesign, which is particularly useful in low- and medium-volume machine programs.
Safety partitioning in harsh non automotive environments
Safety architecture must be aligned with relevant functional safety standards such as ISO 26262 or IEC 61508 depending on the application domain and defined alongside the topology, not added later. Off-highway and robotic platforms can include hazards such as steering loss, unintended motion, boom movement and loss of braking. The required response may be fail-safe shutdown in one machine class and continued degraded operation in another.
A zonal architecture provides several mechanisms for handling this. Critical zones can use redundant power feeds and protected distribution paths. Network availability can be increased through dual links or resilient topologies where cost, weight, and system complexity permit. Safety supervision can be handled by dedicated safety controllers or by safety-capable compute elements that monitor ZCUs and actuators.
The key point for the architect is to map each safety function to the power, network and compute resources that support it, then confirm that those resources provide the required fault tolerance and diagnostic coverage. That mapping also influences physical placement. If a safety-critical harness route is vulnerable to damage, architecture and packaging may need to change together.
Interconnect strategy and physical integration
Harness simplification is one of the main benefits of zonal architectures that only materializes if the connector and cabling strategy is defined early. ZCUs concentrate many power and data interfaces into fewer physical nodes, so connector density, sealing, current rating and service access become architectural issues as well as component-level ones.
Molex publishes material around zonal control units and automotive connectivity, including products for VCU and control-unit interfaces and EV-related high-current interconnects. TE Connectivity publishes information on connectivity for next-generation zonal architectures and on interconnects for commercial and industrial vehicle environments. These resources are useful when defining the physical envelopes and I/O patterns of ZCUs and central compute nodes.
At architecture stage, the important questions are straightforward. How many connectors can a ZCU package realistically support? Which zones need sealed interfaces? Which feeders carry 48 V bulk power, and which carry only signal and data? How many backbone cables cross articulation points, pivots or booms? Answering these questions early, as well as considering EMC/EMI performance, particularly for high-current and high-speed data interfaces, reduces rework later in harness and packaging design.
Example architecture: agricultural sprayer migration
A self-propelled agricultural sprayer provides a useful example because it combines a large physical footprint, distributed actuators and growing automation content. In a distributed ECU layout, the machine may have separate controllers for spray management, boom height, steering, cab functions, telematics and drivetrain support, each with its own supply and network path.
A staged zonal migration can begin by defining the major physical zones: cab, front chassis, rear chassis, left boom and right boom. A 48 V backbone is then added so that each zone can receive protected bulk power from a central conversion stage. ZCUs in the cab, rear chassis and boom sections aggregate local I/O and generate local 12 V rails for nearby loads. Ethernet links tie the ZCUs back to a central compute node, while legacy CAN devices stay within each zone until they are retired or absorbed.
From a system architecture perspective, this migration changes the machine in three important ways. First, it shortens many harness runs by moving local concentration points closer to the devices. Second, it creates a defined backbone for both power and data. Third, it establishes a clearer path for adding autonomy or advanced diagnostics because central compute and local control roles are separated.
What system architects should define first
Before detailed hardware selection begins, several architectural decisions should be fixed.
- Define the physical zones and their environmental classes.
- Define which functions stay local, which functions are centralized and which legacy ECUs remain during migration.
- Define the 48 V backbone topology, conversion stages, local low-voltage rails and any redundant feeds for critical zones.
- Define the data backbone, local networks, gateway boundaries and deterministic networking needs.
- Define the safety partitioning and the fault-containment strategy across power, networking and compute.
- Define the physical interface concept for ZCUs and central compute, including connector count, sealing level and service access.
Making these decisions early helps the program avoid a common trap. Without a clear system architecture, teams often recreate the distributed ECU model inside new hardware packaging, which preserves much of the old complexity and limits the benefits of zonal thinking.
Zonal and centralized E/E architectures are becoming relevant across off-highway vehicles, agricultural platforms and service robots because the same pressures seen in automotive are now present in these sectors: more power, more data, more software and tighter constraints on harness weight and integration effort. For system architects, the value is not in copying passenger-car practice directly. The value is in adapting the core principles, physical zoning, centralized compute where it makes sense, 48 V distribution, local conversion, and structured networking, to the realities of harsh environments and mixed-voltage machines.
A well-partitioned architecture gives engineering teams a clearer path to scalable platforms, phased migration from legacy ECUs and cleaner integration of autonomy, diagnostics and electrified auxiliaries. That is what makes zonal and centralized architectures worth serious attention in off-highway platforms.
