Design and test of a distributed electric tracked chassis using the domain-controlled framework

Electrification, intelligence, and multifunctionality can be promoted in agricultural machinery. In this study, a distributed electric tracked chassis was specifically developed for complex unstructured agricultural terrain. A modular chassis also consisted of the power, walking, electrical control, and intelligent perception system. Among them, the power system was driven by a 72 V lithium battery pack. The power was then provided for two 3 kW permanent magnet synchronous servo motors, each of which was integrated with a planetary gearbox to output the high torque suitable for track drive. The walking system was integrated with the rubber tracks, drive wheels, guide wheels, an independent suspension wheel group, and a tensioning device, thus balancing lightweight with high passability. The electrical control system consisted of the vehicle control unit, motor control units, battery system, and CAN communication network. The torque and energy distribution were responsible for the real-time data interaction with the subsystems. The intelligent perception system was integrated with a GPS/IMU navigation device, PTZ camera, and ultrasonic radar using the intelligent driving domain controller. Precise positioning, environmental perception, and path planning were then achieved in complex agricultural working environments. In the electrical and electronic architecture, the "high-voltage drive - low-voltage control" layered power supply and multi-bus communication topology were adopted to adjust the rapid dynamics and high reliability of the power system. The high-voltage system was powered by the 72 V battery, with the energy distribution and protection using the high-voltage distribution box. The low-voltage system consisted of the 12 and 24 V networks, providing power to the controllers, sensors, communication devices, and braking units. The multi-bus collaborative communication topology included multiple CAN buses and an RS485 bus, the real-time data exchange between the vehicle and motor control units, environmental perception and intelligent control data exchange, as well as the program burning and parameter calibration. The coordinated multi-bus system was obtained through efficient and stable data transmission between control units, providing reliable communication support for the intelligent operation. According to the centralized domain controller and standardized V-model, the application layer software was developed for the chassis domain controller. A model-based design was integrated with the multi-level control functions, signal diagnostics, and functional safety mechanisms. The application layer software was verified the automatically generated code, fully meeting the standard requirements of ISO 26262 functional safety, MAAB modeling, MISRA C 2023 code generation, the software compliance and functional safety. Multi-body dynamic rigid-flexible simulations and prototype testing show that the distributed driven electric tracked chassis was also met the requirements of the power, passability, load capacity, climbing, obstacle-crossing and steering performance. In the maximum speed test, the chassis was operated stably at 2.11 m/s; In the load performance test, the chassis ran smoothly with a 1 500 kg load, with the even track grounding and no slippage or yaw; In the 25° slope climbing test, the chassis demonstrated the stable climbing; In the obstacle-crossing test, the chassis successfully passed the obstacles up to 0.25 m high, with the minimal vertical acceleration and no severe shock or subsidence; In the steering performance test, the chassis exhibited the better trajectory consistency during in-place and small-radius turns, with the maximum deviation controlled within ±2%, and the minimum turning radius 12% smaller than the design value, indicating the excellent steering flexibility and structural stability. Overall, a systematic technical pathway can be obtained for the electronic, electrical, and controller software architecture of the distributed electric-driven crawler chassis for complex agricultural working environments. The finding can also provide the technical and theoretical support for the high-performance and highly adaptable intelligent agricultural machinery.