Intelligent baiting device based on feeding behavior recognition

Abstract

The utility model discloses a kind of intelligent baiting device based on feeding behavior identification, including shell and organism module, storage area module, feeding control and execution module and control and interactive system module, shell and organism module include front shell, rear shell and external fixed support, shell is cuboid, made of anticorrosive ABS engineering plastics, corrosion resistant, storage area module includes cylindrical storage barrel and lower hopper, feeding control and execution module includes feeding port control unit, weight detection unit and bait conveying unit, form "adjustment+weighing+transportation" closed loop structure, control and interactive system module includes raspberry main control board, ULN2003 motor drive module and OLED display interface.The utility model realizes accurate feeding by feeding identification, intelligent control and closed loop regulation, reduce bait waste, reduce water pollution, equipment structure is compact, installation is flexible, applicable to multiple breeding scene, with extensive popularization value.

Description

Technical Field

[0001] This utility model relates to the field of automated aquaculture equipment, and is particularly suitable for intelligent feeding management scenarios such as factory-scale recirculating aquaculture and cage aquaculture. It can accurately reflect changes in the feeding behavior of fish in the water, improve feed utilization efficiency, reduce water pollution, and is widely used in modern aquatic research, green aquaculture, smart fisheries and other technical fields. It is especially suitable for the design of automated feeding systems that require "precise feeding on demand". Background Technology

[0002] In modern aquaculture, feeding is a crucial step in ensuring the growth of aquatic animals and the profitability of aquaculture. Traditional feeding methods mostly rely on manual timed feeding or extensive automatic feeding equipment. These methods generally suffer from problems such as feed waste, delayed feeding response, and inability to adjust the feeding amount according to the actual condition of the fish population. This can easily lead to adverse consequences such as feed accumulation, water quality deterioration, and frequent outbreaks of aquaculture diseases, seriously restricting the improvement of aquaculture efficiency and resource utilization efficiency.

[0003] In recent years, with the development of intelligent fisheries and smart aquaculture technologies, some aquaculture enterprises have begun to try using quantitative automatic feeding devices and remote-controlled feeding equipment to improve feeding accuracy. However, most existing devices only support "timed + quantitative" settings and have not introduced a dynamic sensing mechanism based on fish feeding behavior. They lack the ability to identify and respond to the feeding activity and hunger / satiety status of fish in real time, and are still considered "passive" feeding methods.

[0004] Furthermore, fish feeding behavior is significantly volatile due to factors such as temperature, dissolved oxygen, time, and population density, making fixed-program feeding methods difficult to adapt to dynamic changes in different growth cycles or aquatic environments. Manually observing feeding responses is not only inefficient and subjective but also difficult to scale up. Therefore, intelligent devices for real-time, precise, and on-demand feeding have become a crucial technological breakthrough for improving the intelligence level of modern aquaculture and promoting green and efficient farming. Summary of the Invention

[0005] The technical problem to be solved by this utility model is to provide an intelligent feeding device based on feeding behavior recognition, which aims to solve the problems of traditional aquaculture feeding equipment being unable to feed accurately as needed, feed waste, and uneven feeding.

[0006] A smart feeding device based on feeding behavior recognition adopts a modular structure, including an outer shell and body module, a feed storage area module, a feeding control and execution module, and a control and interaction system module. The device has a reasonable structure, is easy to install, and adapts to different aquaculture environments. The outer shell and body module includes a front shell (1), a rear shell (2), and an external fixing bracket (3). The main body of the outer shell is rectangular and made of corrosion-resistant ABS engineering plastic, making it moisture-resistant and corrosion-resistant. The feed storage area module includes a cylindrical feed hopper (5) and a lower funnel (5). The feeding control and execution system module... The execution module includes a feeding port control unit (6), a weight detection unit (7), and a feed conveying unit (8), forming a closed-loop structure of "adjustment + weighing + conveying". The control and interaction system module includes a Raspberry Pi main control board 9, a ULN2003 motor drive module (10), and an OLED display interface (11). The main control system runs a Linux system, pre-installed with a feeding control program, supports Wi-Fi and wired communication, can receive signals from an external feeding recognition system, and automatically adjusts the feeding parameters according to the feeding level to achieve precise feeding on demand.

[0007] As a preferred embodiment, the threaded interface at the top of the front shell (1) is used to connect the storage bucket, and a silicone O-ring is embedded inside to ensure sealing and moisture protection and support quick disassembly and assembly.

[0008] As a preferred embodiment, the rear shell (2) integrates an OLED display screen and operation buttons. The panel is made of transparent PC material and has a detachable rear cover, which is fixed by bolts and sealing rings to form an independent electrical compartment for installing control circuits and drive modules.

[0009] As a preferred embodiment, the external fixing bracket (3) is used to reliably fix the intelligent feeding device to the edge of the breeding pond or the support platform. The external fixing bracket (3) adopts a C-shaped tiger clamp structure, made of high-strength stainless steel or aluminum alloy, with anti-slip rubber pads inside. The clamping is achieved by adjusting the screw and pressing the pad, ensuring that the equipment remains stable during operation and avoiding displacement or tilting due to vibration or external impact. The external fixing bracket (3) includes a C-shaped clamp (301), an adjusting screw (302), a pressing pad (303), an anti-slip pad (304), and a connecting base plate (305). The C-shaped clamp (301) is made of high-strength stainless steel or aluminum alloy. The connecting base plate (305) is fixed to the bottom of the outer shell by bolts, ensuring that the equipment is stable on the installation platform. It has anti-vibration and anti-impact functions, does not require drilling or welding, and is suitable for various installation environments.

[0010] As a preferred embodiment, the storage hopper (5) is made of food-grade moisture-proof material, with a smooth inner wall and a moisture-proof coating to prevent feed from clumping. The precision threaded interface at the bottom of the storage hopper (5) is screwed into the machine body, and a silicone sealing ring is used to achieve sealing and moisture prevention, and facilitate disassembly and cleaning.

[0011] As a preferred embodiment, the lower funnel (5) adopts a conical structure, and the inner wall of the lower funnel (5) is coated with a wear-resistant layer to ensure that the feed slides smoothly under the action of gravity and avoids blockage.

[0012] In a preferred embodiment, the feeding port control unit (6) is driven by a first stepper motor (601) to drive a double gear set (602) and a double rack guide mechanism (603) to realize the horizontal movement of the gate (604) and control the opening of the feeding port with an accuracy of 0.5mm.

[0013] In a preferred embodiment, the weight detection unit (7) consists of a pressure sensor (701), a weighing platform (702), and an HX711 analog-to-digital converter (703). It collects weight data in real time and feeds it back to the control system. Once the set value is reached, it controls the feeding port to close to prevent overfeeding.

[0014] In a preferred embodiment, the bait conveying unit (8) includes a second stepper motor (801), a spiral conveying rod (802), a reducer (803), and a tail bearing (804). The reducer (803) provides a stable low-speed, high-torque output. The spiral conveying rod (802) is made of stainless steel, and the feeding channel is made of wear-resistant plastic to achieve low-speed, uniform propulsion and avoid blockage.

[0015] As a preferred embodiment, users can remotely monitor the feeding status and adjust parameters via a mobile device. The local OLED interface displays the device's operating status, ensuring independent operation even in abnormal situations. The module adopts a sealed and moisture-proof design and is fixed with an insulating bracket, providing a high level of protection and ensuring long-term stable operation in high-humidity environments.

[0016] The technical principle of this utility model is as follows: This utility model features a dual-motor collaborative design in its mechanical structure. The first stepper motor is linked with a gear-rack mechanism to precisely adjust the opening of the feeding port; the second stepper motor works in conjunction with a screw propulsion device to continuously and evenly push the feed from the storage bin to the feeding port. Compared to traditional single-motor or gravity-feeding devices, this dual-drive structure achieves dual adjustment of "opening control + feeding control," improving the flexibility and accuracy of the feeding process while preventing feed blockage and extending the stable operating time of the equipment.

[0017] This invention employs a partitioned structure of storage area—control area—discharge port, resulting in a simple and smooth feed conveying path, avoiding dead angles and residual feed accumulation. Simultaneously, the spiral propulsion device is installed in an independent sealed channel, effectively preventing moisture and clumping, ensuring smooth discharge of feed of different particle sizes or moisture contents, adapting to the diverse feeding requirements of various farming models. This invention incorporates a telescopic adjustment mechanism in the feed port design, with a gear-rack structure combined with a guide rail, allowing for continuous adjustment of the feed port opening, rather than just fixed-position switching. This design enables the equipment to flexibly adjust the feed flow rate and discharge cross-sectional area according to different feeding intensities, feed types, and feeding strategies, significantly improving adaptability. Furthermore, the telescopic mechanism is fixed at the center of the hopper bottom, ensuring a stable center of gravity and effectively preventing swaying caused by opening adjustments. In addition, the device integrates a weighing module and sensor mounting base, achieving real-time monitoring of the feed weight by arranging a high-precision pressure sensor and support platform below the discharge path. This module adopts a split installation method, which is convenient for disassembly and cleaning, and has a compact structure that does not affect the overall stability. At the same time, with the help of a metal mounting bracket, the equipment's shock resistance and durability during operation are enhanced, ensuring the accuracy of weighing data.

[0018] By adopting the above-mentioned technical solution, this utility model has the following advantages and positive effects compared with the prior art:

[0019] This invention, based on feeding behavior recognition technology, captures images of fish feeding in aquaculture water using a camera and analyzes the feeding behavior in real time using an artificial intelligence model, outputting feeding levels such as "strong," "medium," "weak," and "none" to accurately determine the fish's hunger or satiety status. Compared to traditional methods relying on experience or scheduled feeding, this invention possesses intelligent sensing capabilities, adjusting feeding strategies dynamically based on the fish population, thereby significantly reducing feed waste, preventing water pollution caused by overfeeding, and improving the green and environmentally friendly level of the aquaculture process. Through feeding recognition, intelligent control, and closed-loop regulation, this invention achieves precise feeding, reduces feed waste, and minimizes water pollution. The equipment has a compact structure, flexible installation, and is suitable for various aquaculture scenarios, possessing broad application value. Attached Figure Description

[0020] Figure 1 This is a flowchart of an embodiment of the intelligent feeding system of this utility model.

[0021] Figure 2 This is a schematic diagram of the overall structure of the intelligent feeding device in one embodiment of this utility model.

[0022] Figure 3 This is a schematic diagram of the external fixing frame structure in one embodiment of the present invention.

[0023] Figure 4This is a schematic diagram of the composition structure of the feeding port control unit in one embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of the weight detection unit structure in one embodiment of the present invention.

[0025] Figure 6 This is a schematic diagram of the spiral propulsion unit structure in one embodiment of the present invention. Detailed Implementation

[0026] The embodiments of this utility model are described in detail below with reference to the accompanying drawings: This embodiment is implemented based on the technical solution of this utility model, and provides detailed implementation methods and specific operation processes, but the protection scope of this utility model is not limited to the following embodiments.

[0027] like Figure 1 As shown, the camera collects real-time video data of fish feeding in the aquaculture water. The video stream is transmitted to the intelligent recognition module, which uses an artificial intelligence model to analyze the feeding behavior and outputs the feeding intensity level (strong, medium, weak, none).

[0028] The control system matches a preset feeding strategy based on the fish's feeding level and generates feeding control commands, which are then sent to the feeding control device. The feeding control device includes a feeding adjustment unit and a feeding conveying unit: the adjustment unit precisely adjusts the opening of the feeding port using a gear-rack mechanism driven by a first stepper motor, and collects the feeding weight in real time using a weight detection module; the conveying unit drives a screw conveyor rod using a second stepper motor to evenly push the feed to the outlet, achieving stable feed delivery from the storage area to the feeding end. During feeding, the weight detection module continuously monitors the feeding amount and sends signals back to the control system. When the preset weight threshold is reached, the controller immediately issues a shut-off command, closing the feeding port and stopping the screw conveyor, completing one feeding action. If the feeding amount does not reach the set value, the system continues the conveying operation. After feeding, the camera again captures the fish's feeding behavior, enabling real-time monitoring and secondary adjustments, forming a closed-loop control system of "feeding recognition - feeding execution - weight feedback - behavior verification".

[0029] like Figure 2 As shown, the intelligent feeding device consists of six parts, including the outer shell and body module, the material storage area module, the feeding control and execution module, and the control and interaction system module.

[0030] The outer shell and body module include a front shell 1, a rear shell 2, and an external fixing bracket 3. The main body of the outer shell is rectangular and made of high-strength, corrosion-resistant ABS engineering plastic, possessing moisture resistance, waterproofing, and impact resistance, making it suitable for aquaculture environments. A threaded interface is provided on the top of the front shell for installing a storage hopper. The interface is embedded with a silicone O-ring to ensure a tight seal against moisture and to support quick disassembly for easy cleaning and feeding. The rear shell integrates an OLED display and physical buttons. The control panel is made of transparent PC material and features a removable back cover design. The back cover is secured with bolts and a silicone sealing ring, forming an independent electrical compartment to house the control motherboard, power supply, and drive module, facilitating maintenance.

[0031] The storage area module includes a cylindrical storage hopper 4 and a lower funnel 5, which are installed on the top of the device for feed storage and initial conveying.

[0032] The storage bin 4 is made of food-grade moisture-proof material with a smooth inner wall and a moisture-proof coating to prevent feed from clumping in high-humidity environments. The bottom of the storage bin 4 is equipped with a precision threaded interface, which connects to the top of the machine body by screwing on, and is equipped with a silicone sealing ring to ensure sealing and disassembly for easy and quick cleaning.

[0033] The lower funnel 5 has a conical structure with a smooth inner wall coated with a wear-resistant layer, allowing the feed to slide smoothly under gravity without clogging, ensuring feed flowability, and forming a continuous passage from storage to feeding.

[0034] The feeding control and execution module mainly includes: a feeding port control unit 6, a weight detection unit 7, and a feed conveying unit 8. The feeding port control unit, located above the feeding hopper, uses a stepper motor to drive a gear-rack mechanism, moving the gate horizontally along the guide rail to control the opening of the feeding port. The minimum adjustment accuracy is 0.5mm, ensuring precise and controllable feed flow rate. The weight detection unit, located below the feeding port control unit, consists of a high-precision pressure sensor and an HX711 analog-to-digital converter module. It collects feed weight data in real time and transmits it to the control system. When the set value is reached, it automatically issues a closing command, fully closing the gate to prevent overfeeding and achieve dynamic closed-loop control.

[0035] The control system comprises a Raspberry Pi main control board (9), a ULN2003 motor drive module (10), and an OLED display interface (11). The main control unit runs a Linux system with a built-in feeding algorithm. It can receive external feeding behavior recognition signals and automatically adjust the feeding strategy according to the feeding level, achieving precise feeding on demand. The system supports Wi-Fi and wired communication, allowing users to view the operating status, feeding progress, and remaining feed amount via mobile devices, and modify parameters. The local OLED screen displays real-time status and feeding amount, ensuring manual control is still possible even in the event of network failure. This module features a moisture-proof and sealed design, is fixed inside the electrical compartment, and is capable of long-term stable operation.

[0036] like Figure 3 As shown, the external fixing bracket is used to reliably fix the intelligent feeding device to the edge of the aquaculture pond or the support platform, ensuring the stability of the equipment during operation and preventing displacement or tilting due to vibration or external impact. This structure mainly includes: a C-shaped clamp 301, an adjusting screw 302, a clamping pad 303, an anti-slip pad 304, and a connecting base plate 305. The C-shaped clamp 301 is made of high-strength stainless steel or aluminum alloy, possessing excellent corrosion resistance and impact resistance, and adapting to high humidity and salt spray environments. An anti-slip rubber pad is attached to the inner side of the clamp to increase friction, prevent damage to the platform surface during clamping, and improve clamping stability. The adjusting screw 302 passes through one side of the C-shaped clamp, and precise adjustment of the clamping force is achieved through rotation. A clamping pad 303 is provided at the end; the pad is made of wear-resistant material, which can evenly distribute pressure and prevent structural deformation during clamping. An anti-loosening nut is provided on the outside of the screw to ensure that it does not loosen due to vibration during equipment operation. The base plate 305 is fixed to the bottom of the intelligent feeding device housing with high-strength bolts. The base plate and the C-shaped clamp are connected by welding or high-strength screws to form an integrated support assembly, enhancing seismic resistance. The anti-slip pad 304 is made of wear-resistant rubber, effectively resisting slippery environments and preventing equipment displacement due to moisture and vibration. By rotating the adjusting screw, the clamp can be firmly locked to the edge of the aquaculture pond without drilling or welding on the platform, making installation and disassembly very convenient and allowing for rapid adjustment of the equipment position. This fixing structure not only provides reliable external support for the feeding device, preventing slippage caused by feeding actions or impacts from the screw propulsion, but also has good vibration damping and buffering performance, extending the service life of the equipment. It is suitable for various aquaculture environments and meets the needs of rapid deployment and maintenance.

[0037] like Figure 4As shown, the feeding port adjustment unit is a crucial component of the intelligent feeding device, responsible for precisely regulating the feed flow rate. This ensures dynamic control based on the fish's feeding behavior, preventing feed waste. The unit mainly consists of a first stepper motor 601, a double gear set 602, a double rack and pinion guide mechanism 603, and a telescopic gate structure 604. The first stepper motor 601 is fixedly mounted on the machine frame and precisely controlled by the ULN2003 drive module, enabling fine-tuned step distances with an adjustment accuracy of up to 0.5mm, meeting high-precision feeding requirements. The motor output shaft drives the pinion gear to rotate, which, through the gear set 602 meshing with the rack, converts the rotational motion into linear motion, driving the gate to move horizontally along the guide rail, thus adjusting the feeding port opening. The double rack and pinion guide mechanism 603 is designed to maintain smooth gate movement, preventing deviation or jamming and improving operational reliability. The gate structure 604 is made of wear-resistant ABS material with a smooth surface, reducing feed adhesion and friction, ensuring smooth operation and extending service life. The guide rail is made of aluminum alloy, which is lightweight and has good corrosion resistance, making it suitable for humid and high-salt environments. The adjustment unit achieves precise opening control through the linkage of a stepper motor, gears, and a gate. Combined with instructions from the control system, it adjusts the feeding amount according to the real-time feeding status to ensure uniform feed distribution, forming an intelligent flow management system.

[0038] like Figure 5 As shown, the weight detection unit is a key component for realizing intelligent closed-loop control of feeding, used to monitor the feeding weight in real time to ensure accurate and controllable feed delivery. This unit includes a pressure sensor 701, a weighing platform 702, and an HX711 analog-to-digital converter module 703. The pressure sensor 701 is mounted on the weighing platform 702 below the feeding port adjustment unit and is fixed with high-strength screws to ensure uniform force and stable measurement. The sensor can detect changes in feed weight, converting them into analog signals. These signals are then amplified by the HX711 module and converted into digital signals before being transmitted in real time to the Raspberry Pi main control system. The HX711 module features high-precision amplification and low-noise performance, ensuring the accuracy of the weight data. When the system detects that the cumulative weight has reached the set value, it immediately issues a shut-off command, controlling the feeding port adjustment unit to drive the motor, completely closing the gate, cutting off feed flow, and realizing dynamic closed-loop control of the feeding process. This mechanism not only avoids overfeeding or underfeeding but also ensures the traceability and consistency of each feeding data point. The weight detection unit is designed to be waterproof and corrosion resistant, ensuring long-term stable operation in high-humidity environments and providing hardware support for feeding accuracy.

[0039] like Figure 6As shown, the screw propulsion unit is responsible for evenly conveying the feed, after the feed amount has been adjusted, from the bottom of the funnel to the discharge port, ensuring a continuous and stable feeding process and preventing feed accumulation or blockage. This module includes a second stepper motor 801, a screw conveyor 802, a reducer 803, and a tail bearing 804, and is equipped with a feeding channel. The second stepper motor 801 is mounted on the rear support plate and controlled by the ULN2003 drive module. Its output shaft is connected to the reducer, providing stable low-speed, high-torque performance to meet the mechanical requirements of the feed propulsion process. The screw conveyor 802 is made of stainless steel with a polished surface, providing rust and corrosion resistance and adapting to humid and high-salt environments. The feeding channel is a cylindrical structure made of wear-resistant plastic material, offering lightweight and wear-resistant properties, and facilitating disassembly, cleaning, and replacement, reducing maintenance costs. This module achieves uniform feed delivery through screw propulsion, preventing uneven feeding or blockage caused by gravity flow, ensuring feeding efficiency and stability. Combining the feeding control system and weight detection module, the spiral propulsion module constitutes the key execution link of intelligent feeding, realizing precise control of the entire feeding process.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. An intelligent feeding device based on feeding behavior recognition, characterized in that, The whole adopts a modular structure, including the shell and body module, the storage area module, the feeding control and execution module, and the control and interaction system module. The shell and body module includes the front shell (1), the rear shell (2) and the external fixed bracket (3). The main body of the shell is rectangular and made of anti-corrosion ABS engineering plastic, which is moisture-resistant and corrosion-resistant. The storage area module includes a cylindrical storage bucket (4) and a lower funnel (5). The feeding control and execution module includes a feeding port control unit (6), a weight detection unit (7) and a feed conveying unit (8), forming a closed-loop structure of "adjustment + weighing + conveying". The control and interaction system module includes a Raspberry Pi main control board (9), a ULN2003 motor drive module (10) and an OLED display interface (11). The main control system runs a Linux system, pre-installed with a feeding control program, supports Wi-Fi and wired communication, can receive signals from an external feeding recognition system, and automatically adjusts the feeding parameters according to the feeding level to achieve precise feeding on demand.

2. The intelligent feeding device based on feeding behavior recognition according to claim 1, characterized in that, The threaded interface at the top of the front shell (1) is used to connect the storage bucket, and a silicone O-ring is embedded inside to ensure sealing and moisture protection and support quick disassembly and assembly.

3. The intelligent feeding device based on feeding behavior recognition according to claim 1, characterized in that, The rear shell (2) integrates an OLED display screen and operation buttons. The panel is made of transparent PC material and has a detachable rear cover. It is fixed by bolts and sealing rings to form an independent electrical compartment for installing control circuits and drive modules.

4. The intelligent feeding device based on feeding behavior recognition according to claim 1, characterized in that, The external fixing bracket (3) is used to reliably fix the intelligent feeding device on the edge of the breeding pond or the support platform. The external fixing bracket (3) adopts a C-type tiger clamp structure, is made of high-strength stainless steel or aluminum alloy, and has an anti-slip rubber pad inside. The clamping is achieved by adjusting the screw and the pressing pad. The external fixing bracket (3) includes a C-type clamp (301), an adjusting screw (302), a pressing pad (303), an anti-slip pad (304), and a connecting base plate (305). The C-type clamp (301) is made of high-strength stainless steel or aluminum alloy, and the connecting base plate (305) is fixed to the bottom of the outer shell by bolts.

5. The intelligent feeding device based on feeding behavior recognition according to claim 1, characterized in that, The storage hopper (4) is made of food-grade moisture-proof material, with a smooth inner wall and a moisture-proof coating to prevent feed from clumping. The precision threaded interface at the bottom of the storage hopper (4) is screwed into the machine body and is sealed with a silicone sealing ring to achieve moisture protection and facilitate disassembly and cleaning.

6. The intelligent feeding device based on feeding behavior recognition according to claim 1, characterized in that, The lower funnel (5) adopts a conical structure, and the inner wall of the lower funnel (5) is sprayed with a wear-resistant layer.

7. The intelligent feeding device based on feeding behavior recognition according to claim 1, characterized in that, The feeding port control unit (6) is driven by a first stepper motor (601) to drive a double gear set (602) and a double rack guide mechanism (603) to realize the horizontal movement of the gate (604) and control the opening of the feeding port with an accuracy of 0.5mm.

8. The intelligent feeding device based on feeding behavior recognition according to claim 1, characterized in that, The weight detection unit (7) consists of a pressure sensor (701), a weighing platform (702), and an HX711 analog-to-digital converter (703). It collects weight data in real time and feeds it back to the control system. Once the set value is reached, it controls the feeding port to close to prevent overfeeding.

9. The intelligent feeding device based on feeding behavior recognition according to claim 1, characterized in that, The bait conveying unit (8) includes a second stepper motor (801), a spiral conveying rod (802), a reducer (803), and a tail bearing (804). The reducer (803) provides a stable low-speed, high-torque output. The spiral conveying rod (802) is made of stainless steel, and the feeding channel is made of wear-resistant plastic.

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