Description:TECHNICAL FIELD
[0001] The present disclosure relates, in general, to a pesticide spraying robot for agricultural applications, and more specifically, relates to a robot for the semi-automated dispersion of crop protection materials in agricultural fields.

BACKGROUND
[0002] Traditional handheld sprayers require manual operation, are labor-intensive, and typically have small capacities ranging from 10 to 20 liters, making them suitable for small areas or spot treatments. However, they present significant limitations, such as operator fatigue, health risks from prolonged pesticide exposure, and inefficiency due to frequent refilling, especially when covering large fields.
[0003] Backpack sprayers, which utilize manual pumping, offer slightly larger capacities of 15 to 20 liters and are worn by the operator. Despite their improved portability, these devices still cause physical strain, limited range, and increased health risks due to extended exposure to pesticides. Tractor-mounted sprayers offer motorized operation and larger capacities ranging from 200 liters to several thousand liters. However, their high initial cost and maintenance expenses make them impractical for small-scale farmers. Furthermore, the heavy machinery used in such systems can lead to soil compaction, adversely affecting soil health and crop yields.
[0004] UAV (drone) sprayers have introduced aerial application of pesticides, typically featuring smaller tanks ranging from 5 to 15 liters. However, these systems face several limitations, including high costs, limited battery life, weather dependency, and challenges in maintaining consistent application rates and coverage.
[0005] Therefore, it is desired to overcome the drawbacks, shortcomings, and limitations associated with existing solutions, and develop a pesticide spraying robot configured for small-scale farmers.

OBJECTS OF THE PRESENT DISCLOSURE
[0006] An object of the present disclosure is to provide a robot that improves operational efficiency by eliminating the need for manual pumping and carrying, reducing operator fatigue and minimizing health risks associated with prolonged pesticide exposure.
[0007] Another object of the present disclosure is to provide a robot that significantly enhances coverage capability by incorporating a 120-liter capacity tank, allowing the robot to cover an acre of crops in just 40 minutes, compared to the several hours required for traditional human-operated sprayers.
[0008] Another object of the present disclosure is to provide a robot that minimizes soil compaction due to its lightweight design, making it suitable for small-scale farmers without the adverse effects caused by heavier machinery such as tractor-mounted sprayers.
[0009] Another object of the present disclosure is to provide a robot that offers versatility through sprayer arms that can be adjusted to six distinct angles (0°, 30°, 60°, and 90°) and extended to accommodate various crop widths, making it adaptable to different crop types and orientations.
[0010] Another object of the present disclosure is to provide a robot that increases the consistency of pesticide application by featuring a dual-link configuration, allowing for both top and side spraying, ensuring thorough coverage across the plant, including hard-to-reach areas like lower leaves.
[0011] Yet another object of the present disclosure is to provide a robot that reduces production and maintenance costs by eliminating the need for multiple motors and complex electronics, providing a low-cost, accessible solution for small-scale farmers.

SUMMARY
[0012] The present disclosure relates in general, to a pesticide spraying robot for agricultural applications, and more specifically, relates to a robot for the semi-automated dispersion of crop protection materials in agricultural fields. The main objective of the present disclosure is to overcome the drawbacks, limitations, and shortcomings of the existing structure and solution, by providing a robot for the semi-automated dispersion of crop protection materials in agricultural fields is disclosed. The robot includes a pin-based positioning mechanism accommodated on a frame of the robot. One or more sprayer arms located at a side portion of the frame, pivotally coupled to the pin-based positioning mechanism that is configured to adjust the one or more sprayer arms to at least six distinct angles, wherein the one or more sprayer arms are extendable and retractable to accommodate different types of crops that vary in width, height, size, orientation and any combination thereof.. The robot includes a tank accommodated at a top portion of the frame designed to be filled with crop protection materials to a predefined capacity. A remote controller of the robot is provided to operate the robot through channel mixing for skid steering. Additionally, the robot features a nozzle mounting mechanism configured to support different interchangeable nozzles for optimized spraying performance. The sprayer arms are configured to enable spraying at various orientations, , while being manually adjustable without requiring motorized mechanisms..
[0013] In an aspect, the at least six distinct angles of the one or more sprayer arms are selected from 0°, 30°, 60°, 90°, and any combination thereof. In another aspect, the one or more sprayer arms include extendable links with a length varying between 50 cm and 150 cm to accommodate different types of crops . The one or more sprayer arms are configured with dual-link configurations on each side of the frame to provide both top and side spraying for enhanced coverage. The sprayer arms are configured to apply the crop protection materials at the various orientations pertaining to vertical, horizontal or any combination thereof, to ensure consistent coverage across wide range of crops
[0014] In another aspect, the tank is configured to store a predefined capacity of 120 liters, allowing for extended operation without frequent refills. The crop protection materials selected from pesticides, fertilizers, biological control agents and any combination thereof. In another aspect, the remote controller comprises joystick controls and is configured to enable skid steering for intuitive navigation and manoeuvrability. In another aspect, the nozzle mounting mechanism supports the different interchangeable nozzles selected from flat fan nozzles, flat cone nozzles, and any combination thereof... The robot is configured to travel at an adjustable speed of up to 0.5 meters per second and the robot is ergonomically configured to reduce physical strain on an operator during extended operation.
[0015] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The following drawings form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[0017] FIG. 1A illustrates an exemplary view of robots for the semi-automated dispersion of crop protection materials in agricultural fields, in accordance with an embodiment of the present disclosure.
[0018] FIG. 1B illustrate an exemplary functional component of a robot for semi-automated dispersion of crop protection materials in agricultural fields, in accordance with an embodiment of the present disclosure.
[0019] FIG. 2A to FIG. 2I illustrates exemplary views of pesticide spraying robot, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0020] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0021] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0022] The present invention discloses a pesticide spraying robot designed to enhance efficiency and accessibility for small-scale farmers, wherein the robot employs a manual pin-based positioning system for adjusting sprayer arms to six distinct angles (0°, 30°, 60°, and 90°) without relying on additional motors, thereby simplifying operation and reducing maintenance requirements. The robot is configured to cover an acre of crops in approximately 40 minutes using two extendable links on each side, each having a span of 1.5 meters, significantly improving efficiency in comparison to human-operated methods, which require about 5 hours per acre using a 20-liter sprayer, involving frequent refills, physical strain, and exposure to pesticide inhalation. The robot is further equipped with a 120-liter capacity, which provides enhanced spraying efficiency relative to conventional 30-liter sprayers. Additionally, the robot features remote-controlled operation with skid steering, making it user-friendly and reducing the need for extensive operator training. Cost-effective and lightweight, the robot offers a practical solution for small-scale Indian farmers by providing a more affordable and less soil-compacting alternative to the heavy and expensive tractors typically used by larger-scale farmers.
[0023] The robot for semi-automated dispersion of crop protection materials in agricultural fields is disclosed. The robot includes a pin-based positioning mechanism accommodated on a frame of the robot. One or more sprayer arms located at a side portion of the frame, pivotally coupled to the pin-based positioning mechanism that is configured to adjust the one or more sprayer arms to at least six distinct angles, wherein the one or more sprayer arms are extendable and retractable to accommodate different types of crops that vary in width, height, size, orientation and any combination thereof.. The robot includes a tank accommodated at top portion designed to be filled with crop protection materials to a predefined capacity. A remote controller of the robot is provided to operate the robot through channel mixing for skid steering. Additionally, the robot features a nozzle mounting mechanism configured to support different interchangeable nozzles for optimized spraying. The sprayer arms are configured to enable spraying at various orientations, while being manually adjustable without requiring motorized mechanisms..
[0024] In an aspect, the at least six distinct angles of the one or more sprayer arms are selected from 0°, 30°, 60°, 90°, and any combination thereof. In another aspect, the one or more sprayer arms includes extendable links with a length varying between 50 cm and 150 cm to accommodate different types of crops . The one or more sprayer arms are configured with dual-link configurations on each side of the frame to provide both top and side spraying for enhanced coverage. The sprayer arms are configured to apply crop protection materials at the various orientations pertaining to vertical, horizontal or any combination thereof, to ensure consistent coverage across wide range of crops
[0025] In another aspect, the tank is configured to store a predefined capacity of 120 liters, allowing for extended operation without frequent refills. The crop protection materials selected from pesticides, fertilizers, biological control agents and any combination thereof. In another aspect, the remote controller comprises joystick controls and is configured to enable skid steering for intuitive navigation and manoeuvrability. In another aspect, the nozzle mounting mechanism supports different interchangeable nozzles selected from flat fan nozzles, flat cone nozzles, and any combination thereof. . The robot is configured to travel at an adjustable speed of up to 0.5 meters per second and the robot is ergonomically configured to reduce physical strain on an operator during extended operation. The present disclosure can be described in enabling detail in the following examples, which may represent more than one embodiment of the present disclosure.
[0026] The advantages achieved by the robot of the present disclosure can be clear from the embodiments provided herein. The present disclosure provides the robot configured to improve operational efficiency by eliminating the need for manual pumping and carrying, thus reducing operator fatigue and minimizing health risks associated with prolonged pesticide exposure. The robot further enhances coverage capability through the incorporation of a 120-liter capacity tank, enabling the robot to cover an acre of crops in approximately 40 minutes, a significant improvement over the several hours required for traditional human-operated sprayers. Additionally, the robot minimizes soil compaction due to its lightweight design, making it particularly suitable for small-scale farmers, without the adverse effects typically associated with heavier machinery such as tractor-mounted sprayers. The robot offers versatility by featuring sprayer arms adjustable to six distinct angles (0°, 30°, 60°, and 90°) and extendable to accommodate various crop widths, ensuring adaptability to different crop types and orientations. The dual-link configuration of the robot enhances the consistency of pesticide application by allowing both top and side spraying, providing thorough coverage, including hard-to-reach areas such as lower leaves. Furthermore, the robot reduces production and maintenance costs by eliminating the need for multiple motors and complex electronics, delivering a low-cost, accessible solution for small-scale farmers. The description of terms and features related to the present disclosure shall be clear from the embodiments that are illustrated and described; however, the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents of the embodiments are possible within the scope of the present disclosure. Additionally, the invention can include other embodiments that are within the scope of the claims but are not described in detail with respect to the following description.
[0027] FIG. 1A illustrates an exemplary view of robots for semi-automated dispersion of crop protection materials in agricultural fields, in accordance with an embodiment of the present disclosure.
[0028] Referring to FIG. 1A, pesticide spraying robot 100 (also referred to as robot 100, herein) configured to enhance agricultural efficiency. The robot 100 includes a pin-based positioning mechanism 102, one or more sprayer arms 104, a tank 106, a remote controller 108,nozzle mounting mechanism 110 and frame 112. Each of these components contributes to the robot’s versatility and effectiveness in pesticide application.
[0029] The pesticide spraying robot 100 is equipped with the pin-based positioning mechanism 102 accommodated on the frame 112 of the robot. One or more sprayer arms 104 located at a side portion of the frame 112, pivotally coupled to the pin-based positioning mechanism 102 that is configured to adjust the one or more sprayer arms 104 to at least six distinct angles. The one or more sprayer arms 104 are extendable and retractable to accommodate at different types of crops that vary in width, height, size, orientation and any combination thereof. The pin-based positioning mechanism 102 allows the sprayer arms 104 to be adjusted to at least six distinct angles, including 0°, 30°, 60°, and 90°. This manual mechanism 102 provides precise control over the angle of the sprayer arms 104 without the need for motorized mechanisms. For example, an operator can easily set the sprayer arms to a 45° angle for optimal pesticide application in dense crop rows, using only a simple pin adjustment.
[0030] In another embodiment, the sprayer arms 104 includes extendable links that can be adjusted to accommodate different types of crops . The arms can span up to 1.5 meters, allowing the robot to handle different crop sizes effectively. For instance, when spraying wide rows of crops, the extendable links can be adjusted to cover a broader area, while for narrow rows, the arms can be retracted to focus the application.
[0031] In another embodiment, the pesticide spraying robot 100 is equipped with a pesticide tank 106 accommodated at top portion of the frame 112 capable of holding up to 120 liters of the crop protection materials, the robot 100 can operate for extended periods without frequent refills. The large tank 106 capacity enhances operational efficiency by reducing downtime and maintenance needs. The crop protection materials selected from pesticides, fertilizers, biological control agents and any combination thereof. For example, a farmer can cover a large field with a single tank refill, minimizing interruptions and ensuring consistent pesticide application.
[0032] In another embodiment, the robot 100 includes the remote controller 108 that enables operation via channel mixing for skid steering. The remote controller 108 simplifies navigation and manoeuvring without the need for a microcontroller. For instance, an operator can easily navigate the robot through the field using joystick controls, allowing for precise and intuitive operation.
[0033] In another embodiment, the one or more sprayer arms 104 are configured with dual-link configurations on each side of the frame 112, allowing for multiple spraying orientations, including top and side spraying. This configuration provides enhanced coverage for various crop types. The one or more sprayer arms 104 is configured to apply the crop protection materials at the various orientations pertaining to vertical, horizontal or any combination thereof, to ensure consistent coverage across wide range of crops. For example, in fields with crops growing at different heights, the dual-link setup enables effective spraying both above and alongside the crops.
[0034] The sprayer arms 104 are manually adjustable using the pin-based mechanism, 102 eliminating the need for additional motors to obtain desired arm positions. The manual adjustment mechanism, based on a pin system, eliminates the need for additional motors to position the sprayer arms. This feature simplifies the robot’s design and reduces costs. For instance, operators can manually set the arms to different positions using pins, avoiding the complexity and expense associated with motorized adjustments.
[0035] The robot 100 is configured to be lightweight and cost-effective, making it accessible for small-scale farmers and reducing soil compaction compared to heavier machinery. For example, a small-scale farmer can easily manoeuvre the robot across their fields without causing excessive soil disturbance, ensuring minimal impact on soil health. The adjustable arms 104 (also interchangeably referred to as sprayer arms 104, herein) and extendable links of the robot 100 facilitate efficient pesticide application across both horizontal and vertical crops. This adaptability ensures the robot can meet various agricultural requirements. For example, the robot can be used to spray both high crops like corn and low crops like lettuce, accommodating different growing conditions.
[0036] The remote controller 108 with intuitive joystick controls and skid steering, the robot’s operation is simplified and requires minimal training. For example, an operator can quickly learn to use the robot’s controls, enabling efficient and effective pesticide application with minimal prior experience. The ergonomic design of the robot’s arms and mobile base ensures ease of operation and reduces physical strain on the operator. This design consideration enhances overall usability and effectiveness. For instance, the robot’s comfortable control setup allows operators to work for extended periods without experiencing significant fatigue.
[0037] The sprayer arms 104 are equipped with a nozzle mounting mechanism 110 that supports different interchangeable nozzles, such as flat fan and flat cone nozzles, using a common mount thread. This allows for flexibility in nozzle selection, optimizing the robot’s spraying performance for different applications and pesticide types. For example, the operator can switch nozzles depending on the type of pesticide used, ensuring optimal application for various agricultural needs.
[0038] The pesticide spraying robot 100 includes sprayer arms 104 that can be adjusted to at least six distinct angles, such as 0°, 30°, 60°, and 90°. The length of a single link of the sprayer arms 104 can vary between 50 cm and 150 cm, depending on crop or farmer requirements. The robot 100 is equipped with the pesticide tank having a capacity of up to 120 liters, enabling extended operation without frequent refills. The vehicle speed is adjustable, reaching up to 0.5 meters per second. The robot 100 is operated via the remote controller 108 utilizing channel mixing for skid steering, allowing for intuitive manoeuvrability. The sprayer arms 104 are capable of being configured in multiple orientations, including top and side spraying, and can be manually adjusted without the need for motors. The robot 100 is effective for pesticide application on both horizontal and vertical crops. A simple skid-steering mechanism with joystick control ensures ease of use with minimal training. The robot 100 is ergonomically designed for efficient operation without excessive strain on the operator. Additionally, the sprayer arm 104 is configured to accommodate interchangeable nozzles, such as flat fan and flat cone nozzles, for optimized spraying performance across various applications.
[0039] FIG. 2A to FIG. 2I illustrates exemplary views of pesticide spraying robot, in accordance with an embodiment of the present disclosure. FIG. 2A to FIG. 2I present detailed views of the pesticide spraying robot, showcasing the operational mechanisms of the sprayer arms. These figures illustrate how the sprayer arms are adjusted to different angles, their extendable and retractable capabilities, and the overall configuration for optimized pesticide dispersion. The illustrations provide a clear depiction of how these mechanisms contribute to the robot's functionality in agricultural applications. The robot is disclosed for categorizing crops based on their height and the associated spraying orientations. The crops listed in Table 1 exhibit heights greater than 1 foot and are categorized according to their height ranges and the corresponding spraying orientations required. The crops include Capsicum, Brinjal, Ladyfinger, Tomato, Cucumber, Chili, Beans, Corn, and Bottle Gourd, with heights ranging from 1.5 feet to 9 feet. Each crop is associated with multiple spraying orientations to ensure effective coverage and optimized performance.
Sl. No Crop Name Height Orientations
1 Capsicum 1.5-2.5 ft Various orientations
2 Brinjal 1.5-3 ft Various orientations
3 Ladyfinger 3-4 ft Various orientations
4 Tomato 3-5 ft Various orientations
5 Cucumber 3-6 ft Various orientations
6 Chili 3-6 ft Various orientations
7 Beans 4-5 ft Various orientations
8 Corn 5-7 ft Various orientations
9 Bottle Gourd 6-9 ft Various orientations
Table 1: Sample list of crops with height more than 1 feet.
[0040] The robot is further disclosed for categorizing crops based on their height for efficient spraying operations. Table 2 lists crops with heights less than 1 foot, including Cauliflower, Cabbage, Palak, Beetroot, Onion, Garlic, Carrot, Radish, and Potato. Each crop is designated as a low-height crop with specific type classifications. This categorization facilitates the adaptation of spraying mechanisms to accommodate the shorter heights of these crops, thereby ensuring precise application and improved agricultural practices.
Sl. No Crop Name Height Type
1 Cauliflower 0.5-1 ft Low-height crops
2 Cabbage 0.5-1 ft Low-height crops
3 Palak 0.5-1 ft Low-height crops
4 Beetroot 0.5-1 ft Low-height crops
5 Onion 0.5-1 ft Low-height crops
6 Garlic 0.5-1 ft Low-height crops
7 Carrot 0.5-1 ft Low-height crops
8 Radish 0.5-1 ft Low-height crops
9 Potato 0.5-1 ft Low-height crops
Table 2: Sample list of crops with height less than 1 feet.
[0041] Thus, the present invention overcomes the drawbacks, shortcomings, and limitations associated with existing solutions, and provides the robot configured to improve operational efficiency by eliminating the need for manual pumping and carrying, thus reducing operator fatigue and minimizing health risks associated with prolonged pesticide exposure. The robot further enhances coverage capability through the incorporation of a 120-liter capacity tank, enabling the robot to cover an acre of crops in approximately 40 minutes, a significant improvement over the several hours required for traditional human-operated sprayers. Additionally, the robot minimizes soil compaction due to its lightweight design, making it particularly suitable for small-scale farmers, without the adverse effects typically associated with heavier machinery such as tractor-mounted sprayers. The robot offers versatility by featuring sprayer arms adjustable to six distinct angles (0°, 30°, 60°, and 90°) and extendable to accommodate various crop widths, ensuring adaptability to different crop types and orientations. The dual-link configuration of the robot enhances the consistency of pesticide application by allowing both top and side spraying, providing thorough coverage, including hard-to-reach areas such as lower leaves. Furthermore, the robot reduces production and maintenance costs by eliminating the need for multiple motors and complex electronics, delivering a low-cost, accessible solution for small-scale farmers.
[0042] It will be apparent to those skilled in the art that the robot 100 of the disclosure may be provided using some or all of the mentioned features and components without departing from the scope of the present disclosure. While various embodiments of the present disclosure have been illustrated and described herein, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the disclosure, as described in the claims.

ADVANTAGES OF THE PRESENT INVENTION
[0043] The present invention provides a robot that improves operational efficiency by eliminating the need for manual pumping and carrying, reducing operator fatigue and minimizing health risks associated with prolonged pesticide exposure.
[0044] The present invention provides a robot that significantly enhances coverage capability by incorporating a 120-liter capacity tank, allowing the robot to cover an acre of crops in just 40 minutes, compared to the several hours required for traditional human-operated sprayers.
[0045] The present invention provides a robot that minimizes soil compaction due to its lightweight design, making it suitable for small-scale farmers without the adverse effects caused by heavier machinery such as tractor-mounted sprayers.
[0046] The present invention provides a robot that offers versatility through sprayer arms that can be adjusted to six distinct angles (0°, 30°, 60°, and 90°) and extended to accommodate various crop widths, making it adaptable to different crop types and orientations.
[0047] The present invention provides a robot that increases the consistency of pesticide application by featuring a dual-link configuration, allowing for both top and side spraying, ensuring thorough coverage across the plant, including hard-to-reach areas like lower leaves.
[0048] The present invention provides a robot that reduces production and maintenance costs by eliminating the need for multiple motors and complex electronics, providing a low-cost, accessible solution for small-scale farmers.
, Claims:1. A robot (100) for semi-automated dispersion of crop protection materials in agricultural fields, the robot comprising:
a pin-based positioning mechanism (102) accommodated on a frame (112) of the robot;
one or more sprayer arms (104) located at a side portion of the frame (112), pivotally coupled to the pin-based positioning mechanism (102) that is configured to adjust the one or more sprayer arms (104) to at least six distinct angles, wherein the one or more sprayer arms are extendable and retractable to accommodate different types of crops that varying width, height, size, orientation and any combination thereof; ;
a tank (106) accommodated at top portion of the frame (112), configured to store the crop protection materials to a predefined capacity;
a remote controller (108) of the robot, configured to operate the robot through channel mixing for skid steering; and
a nozzle mounting mechanism (110) coupled to the one or more sprayer arms (104), the nozzle mounting mechanism (110) configured to support different interchangeable nozzles for optimized spraying, wherein the one or more sprayer arms are configured to enable spraying at various orientations, , while being manually adjustable without requiring motorized mechanisms..
2. The robot as claimed in claim 1, wherein the at least six distinct angles of the one or more sprayer arms selected from 0°, 30°, 60°, 90° and any combination thereof.
3. The robot as claimed in claim 1, wherein the one or more sprayer arms (104) comprise extendable links with a length varying between 50 cm and 150 cm to accommodate different types of crops.
4. The robot as claimed in claim 1, wherein the one or more sprayer arms (104) are configured with dual-link configurations on each side of the frame (112) to provide both top spraying and side spraying for enhanced coverage.
5. The robot as claimed in claim 1, wherein the one or more sprayer arms (104) is configured to apply the crop protection materials at the various orientations pertaining to vertical, horizontal or any combination thereof, to ensure consistent coverage across wide range of crops.
6. The robot as claimed in claim 1, wherein the tank (106) is configured to store predefined capacity of 120 liters of the crop protection materials, allowing for extended operation without frequent refills, wherein the crop protection materials selected from pesticides, fertilizers, biological control agents and any combination thereof.
7. The robot as claimed in claim 1, wherein the remote controller (108) comprises joystick controls and is configured to enable the skid steering for intuitive navigation and manoeuvrability.
8. The robot as claimed in claim 1, wherein the nozzle mounting mechanism (110) supports the different interchangeable nozzles selected from flat fan nozzles, flat cone nozzles and any combination thereof.
9. The robot as claimed in claim 1, wherein the robot (100) is configured to travel at an adjustable speed, up to 0.5 meters per second.
10. The robot as claimed in claim 1, wherein the robot is ergonomically configured to reduce physical strain on an operator during extended operation.