Model locomotive distributed sound effect synchronization system based on feedforward compensation and control method

Abstract

The application discloses a model locomotive distributed sound effect synchronization system and control method based on feedforward compensation, which comprises a relay layer and a vehicle-mounted layer connected through a wireless communication link. The relay layer is configured to intercept track control instructions and analyze motion state parameters and function control instructions. The vehicle-mounted layer is configured to receive wireless audio signals and drive a loudspeaker to emit sound. The relay layer comprises a feedforward compensation control module, which is configured to generate and send corresponding audio data packets to the vehicle-mounted layer when a change in the motion state parameters is detected, and then delay for a preset compensation time Δt, and output corresponding motor drive signals to the track power output end, wherein Δt is 15-40 ms. This can effectively complete the auditory dimension of the micro scene, realize sub-millisecond synchronization of locomotive power response and wireless sound effect feedback, and prevent the pitch drift of the fixed frequency semantic sound effect from occurring with the power algorithm.

Description

Technical Field

[0001] This invention relates to the field of model locomotive sound effect processing technology, and in particular to a distributed sound effect synchronization system and control method for model locomotives based on feedforward compensation, for use in DC architecture model locomotives. Background Technology

[0002] Model trains originated in 19th-century Europe and have evolved into a comprehensive panoramic narrative art form integrating precision mechanics, microelectronic control, and miniature landscapes. According to international railway model standards (such as NMRA and MOROP specifications), common physical scales for model trains include: HO scale, N scale (1:160), O scale (1:48), and Z scale (1:220), etc.

[0003] The HO ratio (1:87) is the most complete commercial mainstream ratio in the global industry chain. Due to the ample space inside the vehicle, it can directly accommodate high-power automotive chips, multi-channel traditional automotive decoders and large-size high-fidelity speakers. It focuses on showcasing the independent output of high-precision mechanical linkage and local high-fidelity sound effects. It is mainly used in highly interactive science education, school training tools, and dynamic close-up displays in science museums.

[0004] The N scale (1:160) occupies only about a quarter of the space of the HO scale, and can restore more than 4 times the geographical exhibition area within the same physical area. It is mainly used in large exhibition area sand tables such as grand spatiotemporal narrative simulation, large museums, old railway stations and historical railway lines panoramic digital soundscape restoration.

[0005] Traditional orbital models are mainly divided into two major technical architectures: analog drive (DC) and digital command and control (DCC). The operating principle of analog drive (DC) architecture is to directly control the speed and direction of the motor inside the locomotive by changing the magnitude (typically 0V to 12V / 16V) and polarity of the DC voltage across the guide rails. Under this architecture, the energy flow and control flow on the track are completely and strongly coupled. Only speed, direction, and simple lighting effects can be controlled. This has left existing DC simulator locomotives, which possess extremely high cultural and creative collectible value, in a long-term state of "silence" and "lack of visual feedback," effectively rendered them unusable.

[0006] In a standard Digital Command Control (DCC) architecture, the control flow and energy flow are independent. The core of this architecture lies in the DCC main console, which modulates the digital control instructions generated by the microprocessor (including locomotive-specific double-byte / single-byte logic addresses, speed gears, function key states, etc.) onto a constant alternating high-frequency square wave voltage (typically 12V to 22V, with a frequency generally around 5kHz to 10kHz) using pulse width modulation (PWM), and continuously applies this voltage to both rails.

[0007] At the vehicle end, a highly integrated DCC decoder must be physically connected in series inside the locomotive. Its sophisticated control and digital logic typically include the following components: Power and signal separation: The fast full-bridge rectifier circuit and filter voltage regulator unit at the front end of the decoder convert the high-frequency alternating square wave into a constant DC bus power supply for use by the in-vehicle logic chip and power amplifier; at the same time, the core MCU extracts the complete digital instruction packet from the pulse width variation of the track square wave through opto-isolation or high-speed differential sampling circuit.

[0008] Independent power control: The decoder has a built-in high-frequency (e.g., 16kHz-32kHz) H-bridge motor drive module that supports load compensation (BEMF, back electromotive force feedback) algorithms. It can sense the resistance changes of the motor caused by slopes or curves in real time, automatically adjust the output pulse width, and achieve smooth crawling at extremely low speeds and precise acceleration and deceleration curve simulation.

[0009] Multi-channel output and refined ecosystem: The mature DCC decoder boasts strong functional scalability, providing multiple independent programmable physical output channels. This allows for the construction of a highly realistic physical and digital simulation ecosystem on the miniature model, such as a multi-dimensional visual lighting matrix. This includes independently controllable front and rear directional headlights, simulated red firebox lights mimicking steam locomotives, rotating warning lights for diesel locomotives, undercarriage inspection lights, and independent zoned lighting for passenger carriages. The gradual disappearance effect of the lights can be adjusted via variable parameters (CV value). Dynamic synthesis of complex acoustic logic: The decoder's audio module incorporates a multi-channel digital audio mixer, capable of dynamically changing the tempo and pitch of the steam exhaust sound in real time based on the actual motor load fed back by back electromotive force feedback. It also supports parallel output of multiple audio tracks, allowing users to trigger independent fixed-frequency horn sounds, fan pump sounds, brake exhaust sounds, and station announcements at any time while outputting ambient power sounds. Dynamic intelligent smoke generation system: The advanced decoder can directly drive the electric heating smoke generation unit inside the locomotive, and through a precise logic algorithm, the smoke pump's exhaust volume, injection rhythm, motor speed, and exhaust sound effects achieve a fully closed-loop hard synchronization of mechanics, electricity, and acoustics, perfectly reproducing the physical dynamics of a steam locomotive "exhaling smoke rings".

[0010] 1:160 scale (N scale) railway models, serving as panoramic narrative carriers of "industrial civilization memories," can recreate grand geographical landscapes within a limited exhibition area. However, the internal power mechanisms (motors, worm gear drives, current collectors, etc.) of N scale locomotives typically occupy over 90% of the internal space, leaving insufficient space for electronic components. This extreme physical space constraint pushes traditional digital audio decoding solutions to their physical limits on N scale locomotives. Currently, many existing N scale models with historical collectible value still use analog-driven (DC) architecture. Under this architecture, the analog locomotive operates in a completely "silent" state, unable to reproduce key power sound effects such as steam engine exhaust and internal combustion engine starting. This "sound and image" disconnect strips the soul of industrial cultural and creative works, reducing them to mere mechanical movement. This "loss of voice" is not only a technological shortcoming but also a "loss of historical auditory symbols," resulting in digital cultural and creative projects that, when recreating historical railway scenes, "only have the form but not the soul," lacking the sensory immersion required for digital narratives.

[0011] Furthermore, in simulation mode, the strong coupling between the lights and the power voltage means that when the locomotive starts at low speed or is in a static standby state, it cannot generate stable sound or light feedback independently of the power system, which greatly limits the narrative depth of the static display.

[0012] While DCC (Digital Command Control) retrofit solutions exist in the market, the cost for N-scale motorcycles is often destructive. Firstly, there is significant structural damage: to accommodate the decoder and speakers, the motorcycle's alloy counterweights or precision chassis often require physical cutting, which not only disrupts the model's mechanical balance but also permanently devalues ​​its collectible worth. Secondly, there is acoustic distortion: even if miniature speakers are added, the lack of necessary enclosure often results in a thin and harsh sound. Furthermore, existing solutions generally suffer from "pitch distortion with speed," meaning that sounds like horns and broadcasts, which should maintain a constant frequency, will exhibit a illogical pitch shift as the power voltage increases (i.e., the "Minion screaming effect").

[0013] When writing or modifying locomotive parameters (such as CV values), a standard DCC controller requires the digital locomotive to be connected to the DCC controller's programming rail. At this time, the DCC controller first sends a series of special reset pulses. The digital decoder of the digital locomotive captures these reset characteristics conforming to the NMRA standard and automatically switches its internal state machine from "running mode" to "proxy programming mode." When the controller issues a reprogramming (CV1 write) command, the locomotive, upon receiving the command, generates an acknowledgment pulse (ACK pulse, typically manifested as a momentary current consumption of over 60mA lasting approximately 6ms by instantaneously driving the motor) conforming to international rail transit model standards (such as NMRA). Traditional digital locomotives (i.e., DCC locomotives) generate current through motor vibration, but analog locomotives (i.e., DC locomotives) cannot controllably generate this type of digital feedback. Locomotives that have not undergone deep physical modifications or are still in DC-compatible mode lack the internal hardware unit capable of actively executing this logic control, causing the DCC controller to fail to obtain closed-loop handshake feedback for writing parameters, ultimately leading the system to determine that the write operation has failed.

[0014] Therefore, how to solve the 20ms-50ms physical delay that is common in wireless audio transmission without changing the physical form of the model locomotive (non-intrusive architecture), and achieve the accurate coexistence of dynamic frequency conversion sound effects and fixed frequency semantic sound effects in simulation mode, is a technical bottleneck that urgently needs to be overcome in the field of rail transit model simulation. Summary of the Invention

[0015] This application provides a distributed audio synchronization system and control method for a model locomotive based on feedforward compensation. It can effectively complete the auditory dimension of the miniature scene, achieve sub-millisecond synchronization between locomotive power response and wireless audio feedback, and prevent fixed-frequency semantic audio effects (such as horns and broadcasts) from erroneously drifting in pitch due to the power algorithm.

[0016] The first aspect of this application provides a distributed sound synchronization system for a model locomotive based on feedforward compensation, used in a DC-architected model locomotive, comprising: The relay layer is configured to intercept orbit control commands and parse out motion state parameters and function control commands; The vehicle-mounted layer is configured to receive wireless audio signals and drive speakers to produce sound. The relay layer and the vehicle-mounted layer establish a data transmission connection via a wireless communication link. In specific implementations, this wireless communication link includes, but is not limited to, a Bluetooth Low Energy (BLE) link, a Wi-Fi communication link, a 2.4GHz dedicated wireless frequency band link, or a ZigBee communication link. Preferably, the relay layer and the vehicle-mounted layer use a dedicated BLE channel based on a Universally Unique Identifier (UUID) to achieve one-to-one broadcasting and receiving, to prevent wireless channel crosstalk during multi-vehicle cooperative operation. The relay layer includes a feedforward compensation control module, which is configured to: when a change in motion state parameters is detected, generate and send a corresponding audio data packet first. The audio data packet is transmitted to the vehicle layer through the wireless communication link, and then delayed by a preset compensation time Δt before outputting a corresponding motor drive signal to the track power output end, where Δt is 15ms-40ms.

[0017] In one possible implementation, the relay layer further includes an IAMT storage unit, and the function control instructions include characteristic sound effect instructions and general ambient sound effect instructions. The relay layer performs frequency conversion processing on the characteristic sound effect instructions and frequency fixing processing on the general ambient sound effect instructions according to the attribute identifier in the IAMT storage unit.

[0018] IAMT is a technical abbreviation for "Instruction Attribute Mapping Table".

[0019] In one possible implementation, the frequency conversion processing includes: adjusting the audio sampling rate Fout according to the real-time locomotive speed V, satisfying the formula: Fout = Fref × [1 + λ × (V / Vmax)], where λ is a sensitivity coefficient preset according to the physical characteristics of different locomotive types, Vmax is the maximum speed of the locomotive, and Fref is the reference sampling rate. The reference sampling rate Fref is used to characterize the standard sampling frequency of the original audio file stored in the relay layer, serving as a static baseline for calculating the dynamic resampling step size.

[0020] Furthermore, the maximum locomotive speed Vmax in the formula refers to the digital logical maximum speed value preset by the system and corresponding to the full scale of the current control protocol.

[0021] In one possible implementation, the relay layer is provided with a physical characteristic selection switch and a global gain adjustment knob. The gear switching signal of the physical characteristic selection switch is used to trigger the relay layer to reload the corresponding λ coefficient and the target UUID link of the wireless connection. The global gain adjustment knob is used to map the global volume gain G in real time and adjust the audio sampling rate Fout in combination with motion state parameters.

[0022] In one possible implementation, the relay layer selects the state change of the switch based on physical characteristics to synchronously complete the reloading of audio algorithm parameters and automatic reconnection to the wireless target device.

[0023] In one possible implementation, the relay layer further includes an acceleration determination module, which is configured to: obtain the acceleration vector a by calculating the derivative of the motion state parameters; and automatically trigger the braking sound effect superposition logic when a is less than 0 and the absolute value exceeds a preset threshold.

[0024] In one possible implementation, the relay layer supports multi-channel real-time digital mixing and allows characteristic sound effects that change with motion state to be superimposed and output in parallel with fixed-frequency general ambient sound effects.

[0025] In one possible implementation, the relay layer employs a dual-media storage architecture, including a core area composed of built-in flash memory and an expansion area composed of an external SD card. The core area stores essential sound effects for the locomotive's characteristic domain, and these essential sound effects are locked during firmware flashing to ensure the reliability and read speed of the system's basic simulation. The expansion area stores sound effects from a general resource pool and supports user-defined content. The relay layer is configured to automatically mount the expansion area upon system startup. If the external SD card is detected to be missing or the file is corrupted, reading sound effects from the expansion area is automatically abandoned, while maintaining normal scheduling of sound effects in the core area stored in the built-in flash memory and independent locomotive operation. In another possible implementation, the on-board layer includes an energy storage filter component, configured to maintain the power supply voltage of the on-board layer logic circuit for a preset duration after a track power failure signal occurs, preventing wireless link reset.

[0026] In one possible implementation, the vehicle-mounted layer includes a standardized Jig template chassis, which, in conjunction with the model vehicle body, forms a sealed acoustic resonance cavity.

[0027] In one possible implementation, the vehicle-mounted layer is located on a track and connected between the front of the model vehicle and a carriage adjacent to the front of the model vehicle. The bottom of the vehicle-mounted layer is equipped with wheels, which are used to draw power from the track as a power source.

[0028] In one possible implementation, the relay layer further includes an active impedance simulation unit. When a parameter rewrite command is intercepted, the active impedance simulation unit is controlled to perform a closing action within a preset time window to generate an instantaneous current difference in the track loop as a confirmation pulse. The preset time window is 6ms-10ms, and the instantaneous current difference is 60mA-100mA.

[0029] The second aspect of this application also provides a distributed sound effect synchronization control method for a model locomotive, applied to the aforementioned distributed sound effect synchronization system for a model locomotive based on feedforward compensation, wherein the synchronization control method includes the following steps: Step S1: The relay layer intercepts the orbit control commands and parses out the motion state parameters and function control commands; Step S2: When a change in the motion state parameter is detected, the relay layer first generates a corresponding audio data packet and sends it to the vehicle layer through the wireless communication link to drive the speaker in the vehicle layer to emit sound; Step S3: The relay layer starts a timer and delays for a preset compensation duration Δt, where Δt is 15ms-40ms; Step S4: After the compensation duration Δt ends, the relay layer outputs the corresponding motor drive signal to the track power output end to drive the model locomotive to generate physical displacement.

[0030] Beneficial effects: Compared with the prior art, the model locomotive distributed sound effect synchronization system based on feedforward compensation provided in this application achieves sub-millisecond synchronization of locomotive power response and wireless sound effect feedback through the feedforward compensation mechanism (Δt delay principle), which solves the problem of delay synchronization in wireless transmission of model locomotives; The instruction attribute mapping table (IAMT) can prevent fixed-frequency semantic sound effects (such as horns and broadcasts) from erroneously drifting in pitch due to the power algorithm, solve the linear distortion problem of the model vehicle reception sound effect logic, and solve the simulation problem of the coexistence of variable frequency sound and fixed frequency sound within the same vehicle model. By using a standardized Jig template chassis in conjunction with a model car body to form a sealed acoustic resonance cavity, a non-invasive architecture is created, which can solve the pain points of poor sound quality and inconvenience of modification in N-scale models. By using a dual-media storage architecture, the characteristic sound effects of the model locomotive are embedded in the built-in flash memory, which can effectively prevent the failure of the core simulation logic caused by user misoperation and ensure the security of the core simulation logic. At the same time, the external SD interface allows for the customization of universal sound effects, which balances the high reliability and high openness of the system.

[0031] These and other objects, features and advantages of the present invention will become fully apparent from the following detailed description. Attached Figure Description

[0032] Figure 1 A schematic diagram of the distributed sound synchronization system for a model locomotive based on feedforward compensation, as described in this application, is shown.

[0033] The relay layer includes a command receiving and parsing unit, an integrated control and processing module (including a feedforward compensation control module and an IAMT storage unit), a global gain adjustment knob, a physical characteristic selection switch, a wireless audio transmission unit, a motor drive control module, and an active impedance simulation unit; the vehicle layer includes a full-wave rectifier unit, a wide-voltage regulated converter, an energy storage filter component, a signal receiving and processing module, a power amplifier module, and a speaker.

[0034] Figure 2 A schematic diagram of the DCC controller in this application is shown. In the diagram, POWER IN is the DC power input; Track A is the main track output, which is output to the relay layer when the model locomotive is running; Track B is the programming track output, which is output to the relay layer when the model locomotive command is modified.

[0035] Figure 3 A connection diagram of the distributed sound synchronization system for a model locomotive based on feedforward compensation, as shown in this application, is illustrated.

[0036] Figure 4 A schematic diagram of the subjective evaluation results of the traditional scheme without Δt compensation group is shown.

[0037] Figure 5 A schematic diagram of the subjective evaluation results of the Δt compensation group scheme in this application is shown.

[0038] Figure 6 This diagram illustrates a comparison of subjective evaluation results of the IAMT instruction attribute mapping table's effect on pitch drift suppression. Detailed Implementation

[0039] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0040] Those skilled in the art should understand that, in the disclosure of this specification, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0041] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will also be understood that terms, such as those defined in commonly used dictionaries, shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art and shall not be interpreted as having an idealized or overly formal meaning unless expressly so defined herein.

[0042] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0043] like Figure 1 As shown, the relay layer includes an integrated control and processing module, which integrates a feedforward compensation control module and an IAMT storage unit. The control signal input terminals of the global gain adjustment knob and the physical characteristic selection switch are both connected to the integrated control and processing module. The integrated control and processing module is connected to the command receiving and parsing unit, the wireless audio transmission unit, the motor drive control module, and the active impedance analog unit to achieve full-process control of protocol parsing, feedforward compensation scheduling, voice-changing calculation, and command rewriting. The vehicle-mounted layer includes a full-wave rectifier unit, a wide-voltage regulated converter, an energy storage filter component, a signal receiving and processing module, a power amplifier module, and a speaker, all connected in sequence. The vehicle-mounted layer obtains power from the rails through the wheels at its bottom working in conjunction with the rails. The rail power is processed by a full-wave rectifier unit and a wide-voltage regulator converter to power the energy storage filter components and subsequent circuits. The signal receiving and processing module receives audio data packets sent from the relay layer through the wireless communication link. After unpacking and audio decoding, the data packets are transmitted to the power amplifier module to drive the speaker to produce sound. This, in conjunction with the track power voltage fed forward by the relay layer, achieves sub-millisecond synchronization between the locomotive's power movement and the wireless sound feedback under the premise of non-destructive modification.

[0044] As attached Figure 2As shown, the DCC controller described in this invention uses the open-source DCC-EX-CSB1 as an example. POWER IN is the DC input, generally 10-24 volts, 4-5 amps DC. The specific voltage value depends on the parameters of the digital locomotive placed on the track. Track A is the main track. In digital control, its two output lines are connected to the two tracks respectively. The digital locomotive receives the control signals from the DCC controller to perform actions. Track B is the programming track. In this case, the maximum output current is relatively small and does not meet the requirements for locomotive operation. It is only used when the locomotive needs to be programmed and modified. At this time, the DCC controller will first send a series of special reset pulses. After the digital decoder of the digital locomotive captures these reset characteristics that conform to the NMRA standard, it automatically switches the internal state machine from "running mode" to "proxy programming mode". When the DCC controller issues a reprogramming (CV1 write) command, the locomotive generates an acknowledgment pulse (ACK pulse) that conforms to the international rail transit model standard (such as NMRA) after receiving the command. This pulse is usually manifested as a current consumption of more than 60mA lasting about 6ms by instantaneously driving the motor. Traditional digital locomotives (i.e., DCC locomotives) generate current through motor vibration. Analog locomotives (i.e., DC locomotives), lacking the internal mechanism to analyze signals, cannot controllably generate this type of digital feedback. Therefore, analog locomotives cannot be used for programming modifications.

[0045] refer to Figures 1 to 6 The first aspect of this application provides a distributed audio synchronization system for a model locomotive based on feedforward compensation, used in a DC-architecture model locomotive. The system includes a relay layer and an onboard layer. The relay layer is configured to intercept track control commands and parse motion state parameters and function control commands. The onboard layer is configured to receive wireless audio signals and drive speakers to emit sound. Simultaneously, the relay layer and the onboard layer establish a data transmission connection via a wireless communication link. In specific implementations, the wireless communication link includes, but is not limited to, a Bluetooth Low Energy (BLE) link, a Wi-Fi communication link, a 2.4GHz dedicated wireless frequency band link, or a ZigBee communication link. Preferably, the relay layer and the onboard layer use a dedicated BLE channel based on a Universally Unique Identifier (UUID) to achieve one-to-one broadcasting and receiving, preventing wireless channel crosstalk during multi-vehicle cooperative operation. Specifically, during locomotive model operation, the instruction receiving and parsing unit of the relay layer is connected to the rack A output of the DCC digital controller, i.e., connected to the main rail end. A DC power supply provides power to the relay layer, with the supply voltage matching the locomotive model's voltage. The relay layer's track DC voltage output terminals are connected to the two tracks that power the model locomotive.

[0046] The vehicle-mounted layer is placed on the track, and wheels are installed at its bottom. It can draw power through the cooperation of the wheels and the track, serving as a power source. At the same time, the vehicle-mounted layer is close to the front of the model vehicle, so that the sound outside can be perceived as coming from the front of the model vehicle, making the sound effect simulation more realistic.

[0047] The relay layer includes a feedforward compensation control module, which is configured to: when a change in motion state parameters is detected, or when a change in speed command is identified, not immediately change the track voltage, but instead prioritize generating and sending the corresponding audio data packet to the vehicle layer. Then, a timer or high-precision timer is started to delay for a preset compensation duration Δt. The relay layer then outputs the corresponding motor drive signal to the track power output terminal, causing the motor drive control module to change the DC voltage output to the track, driving the simulated locomotive motor to produce physical displacement. Here, Δt is 15-40ms, for example, 30ms. This delay duration is reserved for wireless transmission and on-board decoding. When the timer ends and the motor drives the locomotive to rotate, the sound is just transmitted from the speaker. Through this asynchronous synthesis of "sound first, electricity later", it is ensured that the physical starting action of the simulated locomotive and the burst of wireless sound effects are completely synchronized at the auditory level, eliminating any perceptual lag and ensuring absolute synchronization of sound and picture.

[0048] Specifically, the distributed sound effect synchronization control method for model locomotives provided in this application mainly includes steps S1 to S4 in its implementation: First, step S1 is executed. The instruction receiving and parsing unit of the relay layer intercepts the DCC control signal on the guide rail and parses out motion state parameters such as speed gear. Next, step S2 is executed. When a change in speed command is detected, an audio data packet is generated and sent to the vehicle layer first. Then, step S3 is executed to start a high-precision timer to delay the preset compensation duration Δt (15ms-40ms). Finally, step S4 is executed. After the timer expires, the relay layer outputs the corresponding DC drive voltage to the track power output terminal to drive the locomotive to move.

[0049] Through the collaboration of steps S1-S4 described above, absolute synchronization of sound and visuals at both the visual and auditory levels can be ensured. For example, during the user-controlled model locomotive's acceleration from a standstill to high speed, the relay layer detects a continuous increase in the speed V value. Instead of immediately changing the track power output, the system prioritizes sending exhaust sound data packets with increasing frequency to the vehicle-mounted layer, internally waiting for Δt=30ms. When the timer ends, the motor drive module outputs voltage. The user observes first hearing a faster exhaust rhythm, followed by synchronized wheel rotation, achieving perfect synchronization of sound and visuals.

[0050] The relay layer also includes an IAMT storage unit. The function control instructions include characteristic sound effect instructions and general ambient sound effect instructions. The relay layer performs frequency conversion processing on the characteristic sound effect instructions based on the attribute identifier in the IAMT storage unit, and performs fixed-frequency processing on the general ambient sound effect instructions to prevent fixed-frequency semantic sound effects (such as horns and broadcasts) from erroneously drifting in pitch due to the power algorithm.

[0051] Specifically, the system uses the integrated control processing module at the relay layer to parse the F0-F28 instructions in the DCC signal and executes the following logic control: 1. F0 Function Retention: In accordance with international standards for track models, the F0 key is reserved for non-audio functions such as headlight control and does not participate in audio logic triggering, ensuring backward compatibility of the system with existing control equipment.

[0052] 2. Level 1: Global Gating (F1): The F1 key is defined as the master volume switch. It uses a single-press toggle mode. The system only allows audio to flow to the wireless link for transmission when F1 is on; when F1 is off, the system is forced to mute.

[0053] 3. Level 2: Locomotive Feature Domain (F2-F9): The sound source in this domain switches between steam / diesel / electric modes based on its characteristics. The system determines the sound attributes through the Instruction Attribute Mapping Table (IAMT). Dynamic item (Bit=1, such as F3 rotating voice): Executes the voice changing formula, and the rhythm and pitch evolve synchronously with the speed V.

[0054] Fixed frequency (Bit=0, such as the horn of an F4 model): The sampling rate is locked and does not change with speed, ensuring the fidelity of the unique timbre of this model.

[0055] 4. Level 3: General Sandbox Resource Pool (F10 and later): Stores common sandbox sound effects such as station arrival announcements and train number announcements. This domain is not affected by vehicle type or gear and enforces fixed-frequency output logic.

[0056] The system implements a tiered allocation strategy for audio sources: Core area (built-in flash memory): Essential sound effects corresponding to the locomotive feature domains (F2-F9). This part of the sound source is locked during firmware flashing to ensure the reliability of the system's basic simulation and read speed (sub-millisecond access).

[0057] Extended Area (External SD Card): Supports long-segment sound effects from the general resource pool (F10 and later). Users can customize content by replacing files. It is automatically mounted at system startup. If the SD card is missing or the files are corrupted, the system will fail to read the files and automatically abandon the process, without affecting locomotive operation or core sound effects.

[0058] The system enforces a mandatory attribute locking strategy: the instruction attributes of the core area (F2-F9) are protected by the system firmware and can only be changed through firmware updates; the extended area (F10 and above) enforces Bit=0 (fixed frequency output) logic by default to ensure the semantic fidelity of the sound effects in the sandbox environment and to reduce the configuration threshold when users customize sound sources.

[0059] For example, in a certain digital cultural and creative project, it was necessary to recreate the operating scene of an old train station from the 1980s. In this case, platform announcements in a specific local dialect and the distinctive whistle sounds of old-fashioned steam locomotives were stored in the relay layer expansion area SD card. During operation, the system uses an IAMT table to layer and overlay the exhaust sounds and dialect announcements, perfectly reproducing the panoramic auditory memory of that historical period without altering the internal structure of the historically significant simulator.

[0060] The relay layer also includes an active impedance simulation unit. When a parameter rewrite command is intercepted, the relay layer controls the active impedance simulation unit to perform a closing action within a preset time window to generate an instantaneous current difference in the track loop as an acknowledgment pulse (ACK pulse).

[0061] For example, the procedure for changing the license plate number of a digital motorcycle to 15 is as follows: The user connects the digital motorcycle to the programming track (Track B) output of the DCC controller to enter programming mode. On the control panel, select "Rewrite CV1" and set the target value to 15, then press the "Confirm / Write" button. At this point, the main console broadcasts the CV1 rewrite command to the track.

[0062] In this application, the configuration variable, or CV value, refers to a digital configuration register parameter conforming to international standards for track models (such as the NMRA standard), used to set attributes such as the logical address, acceleration / deceleration inertia curve, and volume parameters of the model locomotive… Technical Identification: At this point, the DCC controller first sends out a series of special reset pulses. The digital decoder of the digital locomotive (i.e., the DCC locomotive) captures these reset characteristics conforming to the NMRA standard and automatically switches its internal state machine from "operation mode" to "proxy programming mode." When the controller issues a reprogramming (CV1 write) command, the digital locomotive (i.e., the DCC locomotive) generates an acknowledgment pulse (ACK pulse) conforming to international rail transit model standards (such as NMRA), typically manifested as a momentary current consumption of over 60mA lasting approximately 6ms by driving the motor. The relay layer monitors the guide rail signals in real time through a built-in protocol deconstruction algorithm. When a programming mode reset sequence conforming to the NMRA standard is captured, the system automatically switches to "proxy programming state."

[0063] When modifying the car number to 15 for the simulated locomotive (i.e., DC locomotive) modified using this invention, the user connects the DCC signal terminal of the relay layer to the programming track output (Track B) of the DCC controller and enters the programming mode. On the control panel, select "Rewrite CV1" and set the target value to 15, then press the "Confirm / Write" button. At this point, the main control console broadcasts the CV1 rewrite command to the track. The logic for modifying the car number is as follows: 1. Instruction capture: The relay layer intercepted the CV1 address rewrite instruction (Value=15). 2. ACK Pulse Simulation: Within a specific time window after receiving the instruction, the active impedance simulation unit inside the relay layer control performs a precise closing action, with a closing duration of approximately 6ms-10ms.

[0064] The active impedance simulation unit includes a switching element and a power resistor. The relay layer controls the switching element to turn on and off, allowing the power resistor to selectively connect to the track loop.

[0065] Specifically, the active impedance simulation unit includes a power MOSFET switch and a power resistor (e.g., a 200Ω power resistor). The control electrode (G) of the power MOSFET switch is connected to the control pin of the relay layer integrated control processing module. The drain (D) and source (S) of the power MOSFET switch are connected in series with the power resistor and then connected across the track power output circuit. When a parameter rewrite command is intercepted, the integrated control processing module outputs a high-level pulse to the control electrode within a specific time window, controlling the power MOSFET switch to close for 6ms-10ms, causing the power resistor to connect to the track circuit and generate a 60mA-100mA instantaneous current difference (ACK pulse), thereby simulating the hardware response of the on-board decoder.

[0066] 3. Feedback generation: This closing action generates a 60mA-100mA instantaneous current fluctuation (ACK pulse) on the track.

[0067] The DCC controller detects the current fluctuation that conforms to the protocol standard, determines that the "handshake was successful," and confirms the address write. At this point, the relay layer stores address "15" in the built-in flash memory.

[0068] Subsequently, whenever the track broadcast sends a command to "15", the relay layer will automatically respond, realizing a non-intrusive "digital identity reconstruction" of the simulator.

[0069] Furthermore, the frequency conversion processing includes: adjusting the audio sampling rate Fout according to the real-time speed V of the locomotive, wherein the audio sampling rate satisfies the following formula: Fout = Fref × [1 + λ × (V / Vmax)], where λ is the sensitivity coefficient preset according to the physical characteristics of different locomotive types, Vmax is the maximum speed of the locomotive, and Fref is the reference sampling rate.

[0070] Furthermore, the maximum locomotive speed Vmax in the formula refers to the digital logical maximum speed value preset by the system and corresponding to the full scale of the current control protocol. In practical implementation, if the track control command adopts the standard Digital Command Control (DCC) protocol, Vmax corresponds to the highest speed level defined by the protocol (such as level 28 or 128); correspondingly, the real-time motion speed V is the currently intercepted and parsed real-time speed level value. The system calculates the ratio between the real-time motion speed V and the maximum motion speed Vmax to achieve a normalized mapping of the speed variable (with a value range of 0 to 1), which serves as the independent variable for the audio sampling step size pointer offset. This ensures the computational stability of the voice-changing algorithm at the digital logic level and avoids formula overflow caused by physical voltage fluctuations.

[0071] This is the origin of the voice-changing formula principle and the characteristic coefficient λ. The formula simulates frequency modulation in physics, normalizing the real-time speed V (0-1) as an offset variable for the audio sampling step size. The gain adjustment knob is used to set the reference volume G; the system has built-in energy compensation logic, causing the final output volume to dynamically increase slightly with the increase in speed V, simulating the physical energy sensation of a real locomotive traveling at high speed. For example, for steam locomotives, λ≈0.8-1.0, the exhaust sound of steam engines is greatly affected by pressure, the frequency rises sharply, and a high λ value can present a high burst of sound; For example, for diesel / electric locomotives, λ≈0.4: this is a comfortable listening value determined through extensive experimentation. The engine speed of a diesel locomotive increases gradually, and a value of 0.4 ensures that the sound is not sharp or harsh while still allowing for a perceived acceleration. The integrated control and processing module in the relay layer directly reads the original PCM sampling points from the built-in flash memory buffer when executing the resampling voice-changing algorithm. This design avoids potential bandwidth fluctuations that may occur with external SD cards during high-speed pitch-shifting calculations, ensuring the continuity of audio synthesis.

[0072] In some embodiments, the relay layer is equipped with a physical characteristic selection switch and a global gain adjustment knob. The switching signal of the physical characteristic selection switch is used to trigger the relay layer to reload the corresponding λ coefficient and the target UUID link for wireless connection. For example, when a user removes a steam locomotive from the track and replaces it with a diesel locomotive, the operation is as follows: the characteristic selection switch on the relay layer is switched from position 1 (steam) to position 2 (diesel). The relay layer actively releases the current UUID link and rebinds the diesel locomotive ID. The system automatically switches the coefficient λ to 0.4 and reloads the IAMT mapping table for F2-F9, enabling one-click accurate compatibility of heterogeneous vehicle models. The global gain adjustment knob is used to map the global volume gain G in real time and adjust the audio sampling rate Fout in conjunction with motion state parameters.

[0073] In some embodiments, the relay layer synchronously completes the reloading of audio algorithm parameters and automatic reconnection to the wireless target device through the state change of the physical characteristic selection switch. That is, the characteristic selection switch of the relay layer is associated with a set of normalized addressing protocols; when the characteristic selection switch is switched, the system forcibly executes the "link release - address retrieval - reconnection" sequence to achieve accurate directional mapping between physical gear position and specific vehicle model identification code.

[0074] In some embodiments, the relay layer further includes an acceleration determination module, which is configured to: obtain the acceleration vector a by calculating the derivative of the motion state parameters; when a is less than 0 and the absolute value exceeds a preset threshold (such as the deceleration corresponding to 1 / 10 of the time required for the locomotive to stop from its highest speed), automatically trigger the brake sound effect superposition logic, automatically mix the metal brake break-in sound into the audio stream, without requiring manual triggering by the user, which can effectively improve the simulation experience.

[0075] In some embodiments, the relay layer supports multi-channel real-time digital mixing and allows characteristic sound effects that change with motion to be superimposed and output in parallel with fixed-frequency general environmental sound effects. For example, during high-speed cruising of a model locomotive, the user presses F3 (exhaust sound), F4 (siren), and F10 (station announcement) in sequence. Attribute determination: F3 (Bit=1) frequency varies with speed, the sound increases with speed; F4 (Bit=0) maintains the original sampling rate, the tone is stable; F10 (general pool) is absolutely fixed frequency, the speech speed is natural. Through real-time mixing, the system superimposes the three different sound attributes in the speaker, which can truly solve the distortion problem of the station announcement sound becoming shrill with vehicle speed.

[0076] In some embodiments, the vehicle-mounted layer includes an energy storage and filtering component. The energy storage and filtering component is configured to maintain the power supply voltage of the vehicle-mounted layer logic circuits for a preset duration after a track power failure signal occurs, preventing the wireless link from resetting.

[0077] When the system detects an abnormal track voltage input, the energy storage filter component begins to discharge. At this time, the signal receiving and processing module executes a power-limiting strategy, prioritizing the disconnection of the power amplifier module to reduce power consumption, thereby extending the wireless link maintenance time of the core processor under power failure conditions. When track power is restored, the system executes a fast wake-up sequence, seamlessly receiving the real-time audio stream from the relay layer via the I2S bus, achieving a sense of physical continuity in audio playback.

[0078] For example, when a locomotive passes through a power-off section due to poor power supply, the full-wave rectifier unit momentarily loses its input, and the energy storage filter component (supercapacitor) immediately releases its stored energy. Even with a power outage lasting up to 150ms, the onboard unit continues to operate, the wireless link remains unbroken, and power outage restarts and popping noises are avoided.

[0079] In some embodiments, the vehicle-mounted layer includes a standardized Jig template chassis. The standardized Jig template chassis, in conjunction with the model car body, forms a sealed acoustic resonance cavity, allowing the originally thin electronic sound to generate a rich low-frequency feel under the action of the resonance cavity, achieving a physical ecosystem where "changing the shell changes the sound." The model car body can be manufactured using 3D printing technology. The shape of the model car body is consistent with the shape of an existing vehicle body.

[0080] Experiment 1, the effect of Δt feedforward compensation on audio synchronization delay: Experimental objective: To verify the effectiveness of the Δt feedforward compensation mechanism in eliminating wireless audio transmission delay.

[0081] Experimental platform: N-scale (1:160) model locomotive + distributed sound effect synchronization system.

[0082] Comparison group: Traditional scheme without Δt compensation and scheme with Δt compensation in this application.

[0083] Testing method: Subjective scoring method (10-person professional evaluation group, including model enthusiasts, audio engineers, and train model dealers).

[0084] Rating criteria: 1-5 points, where 1 point = severely out of sync, delay > 100ms, sound is severely lagging, unacceptable; 2 points = poor, noticeable delay (50-100ms), affecting immersion, unsatisfactory; 3 points = acceptable, noticeable delay (20-50ms), but acceptable, slightly uncomfortable; 4 points = good synchronization, basically synchronized, very slight delay (<20ms), does not affect the experience; 5 points = perfect synchronization, the rotation of the wheels and the burst of sound are perfectly synchronized, no perceptible delay, excellent immersion.

[0085] Test sample size: 30 acceleration / deceleration actions per group, for a total of 60 evaluations.

[0086] Some test results of the traditional no-Δt compensation scheme are as follows: Figure 4 As shown, by Figure 4 The table data shows that the average subjective score of the traditional no-Δt compensation group was 2.33 points, the standard deviation was 0.14, the 95% confidence interval was [2.23, 2.43], and the overall evaluation was between "poor" and "acceptable". The test results of this application, which include the Δt compensation scheme, are as follows: Figure 5 As shown, by Figure 5 The table data shows that after feedforward Δt compensation, the average subjective score increased to 4.73 points, with a standard deviation of 0.15 and a 95% confidence interval of [4.63, 4.83]. The overall evaluation was between "good synchronization" and "perfect synchronization", with an improvement of up to 103%. At the same time, the rating level improved from poor to acceptable to good synchronization to perfect synchronization, spanning 3 levels. User satisfaction improved directly from dissatisfaction to very satisfaction, with a very significant improvement effect. The standard deviations of the two solutions were quite consistent.

[0087] Experiment 2, the effect of IAMT instruction attribute mapping table on pitch drift suppression: Experimental objective: To verify the effect of IAMT on suppressing pitch drift in fixed-frequency semantic sound effects (sirens, broadcasts).

[0088] Experimental platform: N-scale model locomotive + distributed sound synchronization system.

[0089] Test sound effect: whistle sound (fixed frequency semantic sound effect, should maintain a constant pitch).

[0090] Comparison group: Traditional non-IAMT solution (speed-dependent frequency conversion) vs. the IAMT solution of this application (forced frequency fixing).

[0091] Test method: Blind hearing test by a professional evaluation team of 10 people.

[0092] Rating criteria: 1-5 points (1 point = severely distorted, 5 points = near perfect).

[0093] Subjective evaluation results as follows Figure 6 As shown, by Figure 6 The table data shows that without IAMT, the average score is 1.8, which is severely distorted, with 0% of the scores being perfect and 0% being passing. With the IAMT scheme, the average score is 4.9, which is almost perfect, with 90% of the scores being perfect and 100% being passing.

[0094] In summary, compared with traditional solutions, the distributed sound synchronization system for model locomotives based on feedforward compensation provided in this application, through the "sound first, electricity later" time-for-space strategy in the Δt feedforward compensation mechanism, improves the subjective score of sound-image synchronization from 2.33 points to 4.73 points (out of 5 points), an improvement of 103%. The user perception changes from "sound is obviously lagging behind" to "sound and image are perfectly synchronized", achieving an excellent auditory synchronization experience. In the IAMT instruction attribute mapping table, by stripping away the physical attributes of sound effects at the underlying level, the subjective evaluation of fixed-frequency semantic sound effects (sirens, broadcasts) was improved from 1.8 points (severe distortion) to 4.9 points (near perfect), an improvement of 172%. The user perception changed from "harsh, cartoonish, Minion sounds" to "normal, high fidelity, realistic sirens," completely eliminating the "Minion screaming effect." By combining these two technologies, the two core pain points of "sound field deficiency" and "audio-visual asynchrony" in N-scale model locomotives can be effectively solved, providing solid subjective verification for non-intrusive distributed sound systems.

[0095] It should be noted that this application uses an N-scale DC architecture model locomotive as an example for illustration and description, but it is equally applicable to the modification of model locomotives with other scale DC architectures.

[0096] It should be noted that the terms "first" and "second" used in this application are for descriptive purposes only and do not indicate any order. They should not be construed as indicating or implying relative importance, and can be interpreted as names.

[0097] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the invention. The advantages of the present invention have been fully and effectively realized. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments; any variations or modifications can be made to the implementation of the present invention without departing from these principles.

Claims

1. A distributed sound synchronization system for a model locomotive based on feedforward compensation, used for a DC-architected model locomotive, characterized in that, include: The relay layer is configured to intercept orbit control commands and parse out motion state parameters and function control commands; The vehicle-mounted layer is configured to receive wireless audio signals and drive speakers to produce sound. The relay layer and the vehicle-mounted layer establish a data transmission connection through a wireless communication link; The relay layer includes a feedforward compensation control module, which is configured to: when a change in motion state parameters is detected, generate and send a corresponding audio data packet first. The audio data packet is transmitted to the vehicle layer through the wireless communication link, and then delayed by a preset compensation time Δt before outputting a corresponding motor drive signal to the track power output end, where Δt is 15ms-40ms.

2. The distributed sound synchronization system for model locomotives based on feedforward compensation as described in claim 1, characterized in that, The relay layer also includes an IAMT storage unit. The function control instructions include characteristic sound effect instructions and general ambient sound effect instructions. The relay layer performs frequency conversion processing on the characteristic sound effect instructions and frequency fixing processing on the general ambient sound effect instructions according to the attribute identifier in the IAMT storage unit.

3. The distributed sound synchronization system for model locomotives based on feedforward compensation as described in claim 2, characterized in that, The frequency conversion process includes: adjusting the audio sampling rate Fout according to the real-time speed V of the locomotive, wherein the audio sampling rate satisfies the following formula: Fout = Fref × [1 + λ × (V / Vmax)], where λ is the sensitivity coefficient preset according to the physical characteristics of different locomotive types, Vmax is the maximum speed of the locomotive, and Fref is the reference sampling rate.

4. The distributed sound synchronization system for model locomotives based on feedforward compensation as described in claim 3, characterized in that, The relay layer is equipped with a physical characteristic selection switch and a global gain adjustment knob. The gear switching signal of the physical characteristic selection switch is used to trigger the reload of the relay layer corresponding to the λ coefficient and the target UUID link of the wireless connection. The global gain adjustment knob is used to map the global volume gain G in real time and adjust the audio sampling rate Fout in combination with motion state parameters.

5. The distributed sound synchronization system for model locomotives based on feedforward compensation as described in claim 4, characterized in that, The relay layer selects the state changes of the switch based on physical characteristics, and synchronously completes the reloading of audio algorithm parameters and automatic reconnection to the wireless target device.

6. The distributed sound synchronization system for model locomotives based on feedforward compensation as described in claim 2, characterized in that, The relay layer also includes an acceleration determination module, which is configured to: obtain the acceleration vector a by calculating the derivative of the motion state parameters; and automatically trigger the braking sound effect superposition logic when a is less than 0 and the absolute value exceeds a preset threshold.

7. The distributed sound synchronization system for model locomotives based on feedforward compensation as described in claim 1, characterized in that, The vehicle-mounted layer includes an energy storage and filtering component, which is configured to maintain the power supply voltage of the vehicle-mounted layer logic circuit for a preset duration after the track power failure signal occurs, in order to prevent the wireless link from being reset.

8. The distributed sound synchronization system for model locomotives based on feedforward compensation as described in claim 1, characterized in that, The vehicle-mounted layer includes a standardized Jig template chassis, which, together with the model car body, forms a sealed acoustic resonance cavity.

9. The distributed sound synchronization system for model locomotives based on feedforward compensation as described in claim 1, characterized in that, The relay layer also includes an integrated control processing module and an active impedance simulation unit. The integrated control processing module is configured to: when a parameter rewrite instruction is intercepted, control the active impedance simulation unit to perform a closing action within a preset time window to generate an instantaneous current difference in the track loop as a confirmation pulse, wherein the preset time window is 6ms-10ms and the instantaneous current difference is 60mA-100mA.

10. A distributed sound effect synchronization control method for model locomotives, applied to a distributed sound effect synchronization system for model locomotives based on feedforward compensation as described in any one of claims 1 to 9, characterized in that, The synchronization control method includes the following steps: Step S1: The relay layer intercepts the orbit control commands and parses out the motion state parameters and function control commands; Step S2: When a change in the motion state parameter is detected, the relay layer first generates a corresponding audio data packet and sends it to the vehicle layer through the wireless communication link to drive the speaker in the vehicle layer to emit sound; Step S3: The relay layer starts a timer and delays for a preset compensation duration Δt, where Δt is 15ms-40ms; Step S4: After the compensation duration Δt ends, the relay layer outputs the corresponding motor drive signal to the track power output end to drive the model locomotive to generate physical displacement.

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