Since mass production has rolled off the assembly line in 2022, the third-generation 6-meter-level intelligent driving minibus Chirui has blossomed in many places, and has been widely used in many scenarios such as micro-circulation buses, park commuter ferries, and scenic sightseeing. From the perspective of model market positioning, Chirui is an upgraded product based on market demand and the existing autonomous driving "Xingchen" and "Polaris", and creates two products, No. 1 and No. 2, through the same platform, to meet the needs of two different fields of autonomous driving and micro-circulation buses. From the technical level to the application scenarios, Chirui focuses on the first-mover advantage achieved by Golden Dragon in the field of intelligent driving.
First of all, let's introduce what upgrades have been made in the basic performance of the vehicle as a pure electric low-entrance bus type. First of all, Chirui has been comprehensively optimized in terms of body shape, size and overall arrangement. The shape of the front and rear walls of the body is basically the same, and the side walls are symmetrical design, which not only has a sense of technology and futurism, but also improves the modularity of the vehicle. In order to obtain a larger interior space, the length, width and height of Chirui have reached 5995*2095*2830mm, which is longer and wider than that of models of the same level; In the case of achieving an interior height of 2121mm, the outer height is reduced by 55mm, which is more conducive to the passage of the height limit road section in the park; The wheelbase is shorter, only 3790mm; Under the condition of ensuring the internal space, the vehicle has better passability, and the flexible maneuverability brought by the smaller turning radius is also more suitable for use in scenarios such as microcirculation.
In addition, after the interior space has been improved, Chirui has realized the standard 9+1 seat layout, and the rear seats have been increased from 3 to 4 in similar models. The glass translucent area of the whole vehicle reaches 16.6 square meters, which improves the transparency of the car and provides a good view for the driver and passengers. The net width of the electric plug door reaches 1200mm, which effectively improves the efficiency of loading and unloading during peak operating hours.
Why is Chirui's space and performance better under the same conditions? Behind the seemingly simple data changes is the technical upgrade of vehicle layout and architecture. It is also a 100-degree power model, and the layout scheme of Chirui's 3 battery boxes is 1 at the top, 1 at the front and 1 at the rear, compared with the top 2 and 1 rear scheme, its axle load distribution is more even, which improves the handling stability. In terms of motor, Chirui uses a permanent magnet synchronous motor equipped with a two-stage reducer with a differential, which can provide stronger torque output and protect the motor when climbing and full load. Compared with the unsprung arrangement scheme, Chirui can not only effectively reduce the impact and vibration of the motor, prolong the service life of the motor, but also have better smoothness of the chassis and directly improve the comfort of driving.
After introducing the technical upgrades of the basic model, let's focus on the upgrades of Chirui in terms of intelligent driving. It is understood that Chirui L4 level autonomous driving model completely canceled the driving area in the car, with vehicle-grade solid-state lidar as the main radar, equipped with 8+ solid-state lidar, front and rear millimeter wave radar and 360-degree surround view camera, short-range ultrasonic radar as the sensor of all-round intelligent fusion perception system, integration of global satellite navigation system, sensing technology and feature positioning technology, can achieve centimeter-level high-precision positioning. The wire-controlled chassis adopts multiple redundancy design, the control reaches the millisecond level, and the lateral control accuracy can reach 0.1 degrees.
From the perspective of industrial chain positioning, the core competitiveness of vehicle companies in the field of autonomous driving buses is concentrated in wire-controlled chassis, especially safety control strategies. On the basis of the previous generation model, Chirui adopts multiple heterogeneous redundancy design, providing a variety of execution strategies in terms of software control and hardware execution. Its controller adopts two-way backup, which is equivalent to the vehicle has a "brain" and "cerebellum", and maintains two ways of information interaction and communication in real time. In the event of a failure of the hardware or software of the steering or braking system, the backup system starts working. In terms of braking control, Chirui adopts multiple redundant braking schemes including but not limited to vehicle main braking, auxiliary braking, motor reversal, and parking brake, even in extreme situations, Chirui can still use multi-layer redundant braking to allow the vehicle to safely pull over and wait for rescue. In addition, in order to ensure the safety of the personnel on the vehicle during the test, Chirui also set up an emergency safety stop button within reach of the safety officer, and once the vehicle has an emergency, pressing the emergency stop button can effectively control the vehicle.
The multiple redundancy adopted by Chirui is not complicated in principle, that is, it increases the corresponding backup, but it has extremely high requirements for the control strategy in practical applications. First of all, it is not the redundancy of the function of a certain component, but the deep integration of the entire drive-by-wire chassis system; Second, it should have the same adaptability as experienced drivers in terms of safety control strategies, for example, when the vehicle suddenly has a puncture, the control system needs to give the most correct control strategy at the first time. To achieve the above two points, a lot of practical experience is required, relying on real vehicle testing to continuously verify and debug. Chirui's industry-leading position in the overall control strategy and coordination capabilities of autonomous driving comes from the technical accumulation of Golden Dragon in a variety of autonomous driving products since the batch delivery of "Xingchen" in 2018.
From Xingchen to Chirui, in the process of continuous exploration of self-driving buses, Golden Dragon has also made many breakthroughs in bus intelligent network technology. Based on the technical concept of software-defined buses, Golden Dragon is focusing on building a new electronic and electrical architecture with the integration of five control domains such as body domain and chassis domain as the core, which brings the benefit of higher vehicle integration, better reliability and stability. For example, after adopting the new electronic and electrical architecture, the air conditioning, heater and other equipment of the "Chirui" model have been integrated into the body domain control, bringing a higher intelligent experience to passengers.
Judging from the current overall performance, Chirui has been recognized by all parties in the market, which also shows that Golden Dragon has explored a suitable technical route in the field of intelligent bus driving: that is, based on the needs of real scenarios, build its own core technical capabilities, and promote autonomous driving buses from demonstration operation to real commercial application.
(Author: Yu Zhanbo)