Method and apparatus for providing a dynamic force equilibrium in a LiDAR resonator

Abstract

Device comprising: a spring fork mechanism (550) with a first prong (551) and a second prong (552), wherein the spring fork mechanism (550) is configured to oscillate at a resonant frequency and wherein the stiffness of the first prong (551) is equal to the stiffness of the second prong (552); an optical module (510) attached to the first prong (551) and configured to emit a light pulse and receive a reflection of the light pulse; a voice coil (512) attached to the first prong (551) and configured to generate an alternating magnetic force at the resonant frequency; a counterweight (520) attached to the second prong (552) having a mass and center of gravity equal to the mass and center of gravity of the optical module (510) and the voice coil (512), wherein the counterweight (520) includes a magnet;and a signal source (515) configured to couple an alternating current signal at the resonant frequency into the voice coil (512), so that the voice coil (512) generates the alternating magnetic force at the resonant frequency between the voice coil (512) and the counterweight (520).

Description

introduction

[0001] The technical field generally relates to LiDAR (Light Detection and Ranging) resonators and in particular to a method and device for providing a dynamic force balance in a LiDAR resonator.

[0002] The operation of modern vehicles is becoming increasingly automated, meaning they can provide driving control with ever fewer driver interventions. Vehicle automation has been classified into numerical levels, ranging from zero, which corresponds to no automation with complete human control, to five, which corresponds to complete automation without any human control. Various automated driver assistance systems, such as cruise control, adaptive cruise control, and parking assistance systems, correspond to lower levels of automation, while truly "driverless" vehicles correspond to higher levels.

[0003] Vehicles are increasingly being equipped to autonomously or semi-autonomously perceive and analyze their surroundings using onboard sensors. LiDAR is a surveying technology that measures distances by illuminating a target with laser light. Due to the shorter wavelength of the emitted signal, LiDAR offers higher spatial resolution than radar. However, LiDAR systems must transmit and receive laser light at each resolution point for the depth map, making high-resolution scans over long distances very time-consuming. Current LiDAR systems use stepper motors to rotate and align the laser transmitter, which can be unreliable over extended periods and in harsh environments. Therefore, it is desirable to provide a stable LiDAR scanning mechanism that avoids noise and vibration while ensuring robust operation.Furthermore, other desirable features and properties of the present disclosure will become apparent from the following detailed description and the attached claims, which are made in conjunction with the attached drawings and the aforementioned technical field and background. Summary

[0004] The device is designed to provide a LiDAR resonator with a dynamic force equilibrium. In one embodiment, the device comprises a spring fork mechanism with a first prong and a second prong, wherein the spring fork mechanism is configured to oscillate in resonance at a resonant frequency and wherein the stiffness of the first prong is equal to the stiffness of the second prong; an optical module attached to the first prong, configured to emit a light pulse and receive a reflection of the light pulse; a voice coil attached to the first prong, configured to generate an alternating magnetic force at the resonant frequency; and a counterweight attached to the second prong, having a mass and center of gravity equal to the mass and center of gravity of the optical module and the voice coil.wherein the counterweight contains a magnet, and a signal source configured to couple an alternating current signal at the resonant frequency into the voice coil, so that the voice coil generates the alternating magnetic force at the resonant frequency between the voice coil and the counterweight.

[0005] According to another aspect of the present disclosure, wherein the alternating magnetic force maintains a resonance of the spring fork mechanism.

[0006] According to another aspect of the present disclosure, wherein the alternating magnetic force maintains a phase-shifted resonance of the spring fork mechanism.

[0007] According to another aspect of the present disclosure, wherein the voice coil is integrated with the optical module.

[0008] According to another aspect of the present disclosure, wherein the signal source is integrated with the voice coil.

[0009] According to another aspect of the present disclosure, wherein the signal source is integrated with the optical module.

[0010] According to another aspect of the present disclosure, the light pulse is emitted at a multitude of positions in response to a lateral and vertical movement of the first prong.

[0011] According to another aspect of the present disclosure, further comprising a lens mechanically coupled to a base of the spring fork mechanism, such that the light pulse is emitted through the lens.

[0012] According to another aspect of the present disclosure, wherein the spring fork mechanism is in resonance or resonant at 125 Hz.

[0013] A method for controlling a dynamic force-balanced LiDAR resonator is provided. In one embodiment, the method comprises mechanically coupling a voice coil and an optical module to a first prong of a spring-fork mechanism and a counterweight to a second prong of the spring-fork mechanism, wherein the spring-fork mechanism has a resonant frequency; inducing, through the voice coil, an alternating magnetic force between the optical module and the counterweight to maintain a resonance of the spring-fork mechanism at the resonant frequency; emitting, through the optical module, a first light pulse at a first angle in response to a first position of the first prong and a second light pulse at a second angle in response to a second position of the first prong; and generating a depth map in response to a reflection of the first light pulse.which is received by the optical module at the first position, and a reflection of the second light pulse received by the optical module at the second position, and the steering of a vehicle in response to the depth map.

[0014] According to another aspect of the present disclosure, wherein the voice coil is integrated with the optical module.

[0015] According to another aspect of the present disclosure, the counterweight is magnetic.

[0016] According to another aspect of the present disclosure, wherein the first light pulse and the second light pulse are emitted through a lens that is mechanically coupled to a non-resonant part of the spring fork mechanism.

[0017] According to another aspect of the present disclosure, further including coupling a signal from a signal source to the oscillating module at the resonant frequency.

[0018] According to another aspect of the present disclosure, wherein the spring fork mechanism forms part of a LiDAR resonator.

[0019] According to another aspect of the present disclosure, the vehicle is controlled in response to an assisted driving algorithm.

[0020] According to another aspect of the present disclosure, the voice coil can induce a phase-shifted resonance of the spring fork mechanism.

[0021] According to another aspect of the present disclosure, wherein the optical module is attached to one end of the first prong of the spring fork mechanism.

[0022] According to another aspect of the present disclosure, a vehicle comprising a lidar, a spring fork mechanism with a first prong having a first stiffness and a second prong having a first stiffness, wherein the spring fork mechanism is configured to oscillate in resonance at a resonant frequency, an optical module attached to the first prong for emitting a light pulse and receiving a reflection of the light pulse, a voice coil attached to the first prong for generating an alternating magnetic field at the resonant frequency, and a counterweight attached to the second prong having a mass and center of gravity equal to the mass and center of gravity of the optical module and the voice coil, and a signal source for coupling an alternating current signal at the resonant frequency into the voice coil.so that the voice coil can generate an alternating magnetic force at the resonant frequency between the voice coil and the counterweight, a processor to generate a depth map in response to a transmission time of the light pulse and a detection time of the reflection of the light pulse, a memory to store the depth map, and a vehicle controller to control the vehicle in response to an assisted driving algorithm and the depth map.

[0023] According to another aspect of the present disclosure, wherein the alternating magnetic force maintains a phase-shifted resonance of the spring fork mechanism. Brief description of the drawings

[0024] The exemplary embodiments are described below in conjunction with the following drawing figures, where identical numbers denote identical elements and where: Fig. 1 an exemplary environment for the use of a LiDAR system in a host vehicle which includes a dynamic force balance LiDAR resonator according to an embodiment; Fig. 2 an exemplary LiDAR resonator with dynamic equilibrium design according to one embodiment; Fig. 3 a method for controlling a LiDAR resonator with a dynamic equilibrium design according to one embodiment; Fig. 4 an exemplary vehicle system comprising a LiDAR resonator system with a dynamic equilibrium design according to one embodiment; and Fig. 5 is another LiDAR resonator with a dynamic equilibrium design according to one embodiment. Detailed description

[0025] The following detailed description is by its very nature exemplary and is not intended to limit applications and uses. Furthermore, one should not be bound by any express, implied, or tacit theories presented in the preceding technical field, background, summary, or the detailed description that follows. As used herein, the term module refers to an application-specific integrated circuit (ASIC), an electronic circuit, a processor (common, dedicated, or group), and memory executing one or more software or firmware programs, a combinational logic circuit, and / or other suitable components providing the described functionality.

[0026] If one now turns Fig. Figure 1 shows an exemplary environment 100 for the use of a LiDAR system in a host vehicle 110, which contains a dynamic force-balanced LiDAR resonator, according to various embodiments. In some exemplary embodiments, the LiDAR system within the host vehicle 110 is configured to generate a depth map of a two-dimensional field of view 130. Although the exemplary field of view 130 is shown as a forward-facing field of view, the system is applicable to any field of view. One area of ​​the field of view 130 corresponds to a range of viewing angles 120 of the LiDAR transceiver.

[0027] The exemplary LiDAR system uses a variety of fixed or stationary LiDAR transceivers, each with a field of view covering a portion of the field of view 130. For example, each LiDAR transceiver can acquire depth measurements at 16 horizontal points and 4 vertical points. The fields of view of each of the stationary LiDAR transceivers can partially overlap to facilitate alignment across the fields of view, or they can have contiguous fields of view to increase resolution and reduce scan time for the field of view 130.

[0028] A LiDAR transceiver typically has an optical module with a laser emitter and a light detector. A lens, mirrors, and / or a mechanical scanner can be used to focus and direct a light pulse emitted by the stationary LiDAR system to a desired azimuth and elevation. A pulse of reflected light is directed back onto a detector by the same lens and / or mirror mechanism. The travel time of the emitted and reflected light pulses is used to determine a distance, or depth, to a surface at the specified azimuth and elevation angles. This distance is then combined with acquisitions at other azimuth and elevation angles to create a depth map. The distance and / or angle between the acquisitions or detections is referred to as the resolution.Higher-resolution depth maps contain more depth points for a given area, while lower-resolution depth maps contain fewer depth points for the same area. Higher-resolution depth maps require more time to acquire and process. Therefore, very high-resolution depth maps can be impractical for real-time applications, such as controlling an autonomous vehicle.

[0029] If one now turns Fig. Figure 2 shows an exemplary LiDAR resonator 200 with a dynamic equilibrium design according to various embodiments. The exemplary LiDAR resonator comprises a lens 220, a base structure 255, two optical modules 230, two counterweights 240, two voice coils 250, and two two-pronged resonating forks 210.

[0030] In some exemplary embodiments, the LiDAR resonator 200 includes a resonant structure with two two-pronged resonant forks 210 and a mounting pin 260 for attaching the resonant structure to a base structure 255. The resonant structure is configured such that dynamic equilibrium is achieved by internal cancellation of the operating forces between the two prongs of each resonant fork 210. Each of the two-pronged resonant forks 210 is configured to accommodate an optical module 230, a counterweight 240, and a voice coil 250. A lens 220 is arranged at one end of the base structure 255, opposite the prong ends of the two-pronged resonant fork, the optical module 230, the voice coil 250, the counterweight 240, and the magnet.

[0031] In some exemplary embodiments, the two-pronged resonant forks 210 are spring forks configured to resonate at the desired LiDAR scan frequency of the optical module 230. The counterweight 240 is configured such that the weight of the optical module 230 on one prong is balanced by the voice coil 250, and the counterweight 240 on the opposite prong is balanced by the magnet. The balanced masses, with equal CGs at each end of the two prongs, facilitate resonance at the desired frequency. In some exemplary embodiments, the desired resonant frequency is 125 Hz in the lateral direction and 120 Hz in the vertical direction. The voice coil 250 is configured to generate an alternating magnetic field between the optical module 230 and the counterweight 240 to initiate and maintain resonance at the desired frequency.

[0032] In response to the vibration of the resonating fork, each of the optical modules 230 is displaced laterally and vertically, thereby changing the point of incidence of a light pulse emitted by optical module 230 onto the lens 220. The lens 220 is configured to focus and transmit the incident light pulse to achieve a desired scan area for the light pulses emitted and received by the LiDAR resonator 200. The optical module 230 is further equipped with an optical detector to detect the received light pulse and determine a distance within the desired scan area. This distance within the desired scan area is then used with other detected distances to generate a depth map for use by a vehicle controller.

[0033] In some exemplary embodiments, the LiDAR resonator 200 is configured such that a voice coil 250 is integrated with the optical module 230 and a magnet with the counterweight 240, thus eliminating the LiDAR operating force. The counterweight 240 and the optical module 230 form a system with two interconnected single degrees of freedom in each direction (vertically and laterally independent) with the two-pronged resonating fork 210. In the exemplary configuration of counterweight 240 and optical module 230 / voice coil 250, only the phase-shifted motion is excited, without any in-phase component.

[0034] Previously, the voice coils had been attached to the base structure of older LiDAR resonators. Mounting the voice coil to the base structure created an unbalanced force between one prong of the two-pronged resonating fork and the base structure. This unbalanced force resulted in excessive noise and vibration, which were perceptible to vehicle occupants. Furthermore, the unbalanced forces increased the power consumption of the voice coil attached to the base structure and could reduce the operating efficiency and / or robustness of the older LiDAR resonator. To address these problems, the exemplary LiDAR resonator 200 was configured with a voice coil 250, an optical module 230, and a counterweight 240, which were mounted in a weight-balanced configuration at the ends of the prongs of the two-pronged resonating forks 210.Thus, when the voice coil 250 induces the resonance mode of the two-pronged resonant fork 210, the same and opposite force is exerted on each of the forks. Advantageously, by providing a balanced and opposite force between the two forks, the forks move out of phase with each other, or phase-shifted, thereby further balancing the forces in the resonant fork and further reducing noise and vibration of the LiDAR resonator 200.

[0035] The modal analysis of the exemplary two-pronged resonant fork 210 indicates two possible types of modes: one is an in-phase mode, in which the counterweight 240 and the optical module 230 move in the same direction, and the other is an out-of-phase mode, in which the counterweight 240 and the optical module 230 move in opposite directions. By moving the voice coil 250 so that it collocates with the optical module 230, the excitation of the counterweight 240 involves action / reaction forces that are always equal but in opposite directions, with the total force at one base of the two-pronged resonant fork 210 perfectly canceling each other out due to the equal mass, the same center of gravity (CG), and the same stiffness at each of the two prongs. Thus, the effect of the in-phase mode vibrations on the basic structure 255 is eliminated.The exemplary LiDAR resonator 200 exhibits a state of dynamic equilibrium, as both in-phase and out-of-phase motion minimize vibrations in the base structure 255 and the vehicle structure as a whole. This dynamic equilibrium can further reduce power consumption by generating the same range of motion at the optical module 230 for laser scanning with less force applied by the voice coil 250.

[0036] If one now turns Fig. Figure 3 shows an exemplary method 300 for controlling a LiDAR resonator with a dynamic equilibrium design according to various embodiments.

[0037] The method initially serves to mechanically couple a voice coil and an optical module to a first prong of a spring-fork mechanism, and a counterweight and a magnet to a second prong of the spring-fork mechanism 310, wherein the spring-fork mechanism has a resonant frequency. In some exemplary embodiments, the voice coil and the optical module can be mechanically coupled to a distal end of the prong that is furthest from a base of the spring-fork mechanism. Coupling the optical module to the distal end of the prong results in the greatest lateral and vertical movements of the optical module when the spring-fork mechanism is in its resonant state. A lens for focusing and for adjusting or setting a desired transmission angle can be mechanically coupled to the base of the spring-fork mechanism either directly or via a support structure.

[0038] The voice coil then serves to induce an alternating magnetic force between the optical module and the counterweight 320 to maintain resonance of the spring-fork mechanism at the resonant frequency. The voice coil can be positioned so that the alternating magnetic force is directed towards the counterweight, resulting in a balanced, phase-shifted resonance of the spring-fork mechanism. The counterweight can be a magnet, contain a magnet, or have a magnetic surface to improve the efficiency of the voice coil operation, thereby reducing power consumption and increasing the system's lifetime. In some exemplary embodiments, the voice coil can be integrated within the optical module or receive power and / or an AC signal from the optical module.

[0039] The next step involves using the optical module 330 to emit a first light pulse at a first location in response to the first position of the first prong, and a second light pulse at a second location in response to the second position of the first prong. The angle of the emitted beam from the optical module is changed in response to the lateral and vertical movement of the first prong of the optical module, which results from the lateral and vertical movement of the first prong during the resonance mode of the spring fork mechanism. The light pulses emitted by the optical module have different points of incidence on the lens, resulting in different light pulse transmission points from the lens towards the field of view.In some exemplary embodiments, the first light pulse and the second light pulse are emitted through a lens that is mechanically coupled to a non-resonant part of the spring fork mechanism.

[0040] Next, a depth map is created in response to a reflection of the first light pulse received by the optical module at the first position and a reflection of the second light pulse received by the optical module at the second position. The propagation time of the light pulses between the emission of the light pulse and the detection of a reflection of the light pulse is used to determine a distance to a surface at the light pulse transmission angle.

[0041] The method next serves to control a vehicle in response to the depth map. The depth map can be used to generate a point cloud of an area near the vehicle. The vehicle is controlled in response to an assisted driving algorithm that uses the depth map, the point cloud, data from a global positioning system (GPS), and / or map data stored in memory. In some exemplary embodiments, the assisted driving algorithm may be an adaptive cruise control algorithm.

[0042] If one now turns Fig. Reference 4 to an exemplary vehicle system 400, which includes a LiDAR resonator with a dynamic equilibrium design according to various embodiments, is presented. The exemplary vehicle system 400 comprises a first camera 410, a second camera 412, a LiDAR 430, a LiDAR processor 435, an image processor 415, an ADAS processor 460, a user interface 465, a GPS 475, and a vehicle controller 455.

[0043] The first camera 410 can be mounted on a host vehicle with a forward-facing or front field of view. The first camera 410 can be mounted on the host vehicle's radiator grille, behind a rearview mirror, or on the leading edge of the host vehicle's roof. The first camera 410 can be configured to capture an image of the front field of view and couple this image into the image processor 415. Additionally, a second camera 412 can be mounted on one or more side mirror housings with a second field of view that partially overlaps with the front field of view. In some exemplary embodiments, the image from the first camera 410 and an image captured by the second camera 412 can be combined by the image processor 415 to produce an extended view image that includes both the first and second fields of view.The first camera and the second camera can be configured to capture or record light in the spectral range of 400nm to 700nm, or can include a long-wave infrared camera sensor and / or a short-wave infrared camera sensor.

[0044] The LiDAR 430, which includes a LiDAR resonator according to the exemplary embodiments, is configured to emit a light pulse at a known azimuth and elevation and receive a reflection of the light pulse from a distal object. The LiDAR 430 and / or the LiDAR processor 435 can determine a distance to the distal object in response to the propagation time of the light pulse. The LiDAR 430 can couple this distance measurement for the known azimuth and elevation to the LiDAR processor 435 to generate a depth map and / or a point cloud. A depth map contains distances for a variety of azimuth and elevation angles to create a depth representation of the LiDAR 430's field of view. A point cloud is a three-dimensional visualization of the depth map. LiDAR systems typically use light in the range of 750 nm to 1500 nm.Advantageously, the light pulses emitted by the LiDAR 430 can illuminate the field of view, with the reflected light being captured by a detector within an optical module.

[0045] The images captured by the first camera 410 and the second camera 412 can be coupled into the image processor 415 for further processing to enable object detection for input into an ADAS algorithm. This further processing can include inverted or linearized gamma correction, histogram smoothing, and edge detection. The image processor 415 can then be configured to combine the data from the multiple received images into a fused image. The fused image can exhibit an increased field of view, dynamic range, and / or resolution compared to each of the individual images. The image processor 415 can then perform inverted or linearized gamma correction, histogram smoothing, and edge detection on the fused image.Object detection and classification can then be performed using the results of image processing on the fused image and the resulting data, which are fed into the ADAS processor 460. Object detection on either the fused image or the image from the first camera 410 can be performed using a trained neural network. The object detection results can be used to further train the neural network.

[0046] The object detection results and the point cloud or depth map can then be fed into the ADAS processor 460. The ADAS processor 460 can use the information about detected objects, the point cloud, the map data stored in a memory 470, and the location data received in response to a GPS 475 to generate a map of the localized area or region relative to the host vehicle. The ADAS processor 460 can also be used to generate control signals in response to an ADAS algorithm for feeding into the vehicle controller 455 to control the host vehicle. For example, the ADAS algorithm can perform adaptive cruise control operation and generate steering, braking, and throttle control information for feeding into the vehicle controller 455.Alternatively, the ADAS controller can generate a motion path in response to information about detected objects and the LiDAR point cloud and couple this motion path into the vehicle controller 455.

[0047] The user interface 465 can be configured to receive user input to initiate an ADAS algorithm. Furthermore, the user interface 465 can be configured to display user warnings and / or feedback from the ADAS system to a driver in response to a control signal for a user alarm generated by the ADAS processor 460 and / or the vehicle controller 455.

[0048] If one now turns Fig.Figure 5 illustrates an exemplary LiDAR resonator 500 with dynamic force equilibrium according to various embodiments. The exemplary LiDAR resonator 500 can comprise a spring fork mechanism 550 with a first prong 551 and a second prong 552, an optical module 510, a voice coil 512, a counterweight 520, a signal source 515, a LiDAR processor 530, and a vehicle controller 540.

[0049] The spring fork mechanism 550 is configured to oscillate at a resonant frequency. In some embodiments, the resonant frequency can be 120 Hz in the vertical direction and 125 Hz in the lateral direction. To reduce external vibrations and noise, it is desirable for the spring fork mechanism 550 to have a phase-shifted resonance. In a phase-shifted resonance, for example, the first prong 551 moves in the opposite direction to the second prong 552.

[0050] The optical module 510 can be attached to the first prong 551 and emit a light pulse and receive a reflection of the light pulse. The optical module 510 can be configured to emit light pulses at a rate of 8 kHz. In some exemplary embodiments, the optical module 510 can emit light pulses at a variety of angles in response to a lateral movement of the first prong generated by the resonance of the spring fork mechanism 550. For example, if the optical module 510 is configured to emit at a pulse rate of 8 kHz and the spring fork mechanism 550 resonates at 125 Hz, the optical module 510 can emit at 64 different transmission positions resulting from the lateral and vertical movement of the end of the first prong 551.

[0051] The voice coil 512 serves to generate an alternating magnetic field at the resonant frequency. The voice coil 512 can be attached to the first prong 551 and collated or connected to the optical module 510. The alternating magnetic force generated by the voice coil 512 is directed towards the counterweight 520 on the second prong 552 and serves to maintain a resonance of the spring fork mechanism 550, such as a phase-shifted resonance of the spring fork mechanism 550. In some exemplary embodiments, the voice coil can be integrated into the optical module 510. Alternatively, the voice coil 512 can be collated or arranged together with the counterweight 520 on the second prong, and a magnetic surface can be applied to a portion of the optical module 510 such that the alternating magnetic force generated by the voice coil 512 is directed towards the magnetic surface.

[0052] The counterweight 520 can be attached to the second prong and have a mass equal to the mass of the optical module 510 and the mass of the voice coil 512. The counterweight can be a magnet, contain a magnet, or have a magnetic surface. Preferably, a magnetic part of the counterweight 520 can be located near the voice coil 512.

[0053] The exemplary LiDAR resonator 500 can further include a signal source 515 for coupling an alternating current signal at the resonant frequency into the voice coil 512, so that the voice coil 512 can generate an alternating magnetic force at the resonant frequency between the voice coil 512 and the counterpoise 520. The signal source 515 can be integrated with the voice coil 512 or with the optical module 510. In some exemplary embodiments, the signal source can generate a sinusoidal electrical signal of 120 Hz and / or 125 Hz, which is provided to one or more voice coils.

[0054] The LiDAR resonator 500 can further include a LiDAR processor 530 for receiving data related to the transmission and detection of pulses, which the processor 530 can use to generate the depth map and / or a point cloud for the field of view. This depth map and / or point cloud can be provided to a vehicle controller 540 for controlling a vehicle during the operation of an advanced driver assistance system (ADAS), such as adaptive cruise control or the control of an autonomous vehicle. The LiDAR resonator can further include a lens that is mechanically coupled to a base of the spring-loaded fork mechanism 550, so that the light pulse emitted by the optical module is transmitted through or emitted by the lens.

[0055] Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that a large number of variants exist. It should also be understood that the exemplary embodiment or embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description is intended to provide the person skilled in the art with a practical guide for implementing the exemplary embodiment or embodiments. It should be understood that various modifications in the function and arrangement of the elements can be made without deviating from the scope of the disclosure as set forth in the appended claims and their statutory equivalents.

Claims

[1] Device comprising: a spring fork mechanism with a first prong and a second prong, wherein the spring fork mechanism is configured to oscillate at a resonant frequency and wherein a stiffness of the first prong is equal to a stiffness of the second prong; an optical module attached to the first prong, configured to emit a light pulse and receive a reflection of the light pulse; a voice coil attached to the first prong, configured to generate an alternating magnetic force at the resonant frequency; a counterweight attached to the second prong, having a mass and center of gravity equal to the mass and center of gravity of the optical module and the voice coil, the counterweight containing a magnet; and a signal source configured to couple an alternating current signal into the voice coil at the resonant frequency, so that the voice coil generates the alternating magnetic force at the resonant frequency between the voice coil and the counterpoise. [2] Device according to claim 1, wherein the alternating magnetic force maintains a resonance of the spring fork mechanism. [3] Device according to claim 1, wherein the alternating magnetic force maintains a phase-shifted resonance of the spring fork mechanism. [4] Device according to claim 1, wherein the voice coil is integrated with the optical module. [5] Device according to claim 1, wherein the signal source is integrated with the voice coil. [6] Device according to claim 1, wherein the signal source is integrated with the optical module. [7] Device according to claim 1, wherein the light pulse is emitted at a plurality of positions in response to a lateral and vertical movement of the first prong. [8] Device according to claim 1, further comprising a lens which is mechanically coupled to a base of the spring fork mechanism, so that the light pulse is emitted through the lens. [9] Device according to claim 1, wherein the spring fork mechanism resonates at 125 Hz. [10] Procedures, including: mechanical coupling of a voice coil and an optical module with a first prong of a spring fork mechanism and a counterweight with a second prong of the spring fork mechanism, wherein the spring fork mechanism has a resonant frequency; Induce, through the voice coil, an alternating magnetic force between the optical module and the counterweight to maintain a resonance of the spring fork mechanism at the resonant frequency; Emitting, through the optical module, a first light pulse at a first angle in response to a first position of the first prong and a second light pulse at a second angle in response to a second position of the first prong; Generating a depth map in response to a reflection of the first light pulse received by the optical module at the first position, and a reflection of the second light pulse received by the optical module at the second position; and Steering a vehicle in response to the depth map.

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