Method for preventing platform of overhead working truck from touching ground and colliding

Abstract

The invention discloses an overhead working truck platform ground-contact collision prevention method, which comprises the following steps of: S100, setting related parameters for ground-contact collision prevention of a working platform, and delimiting a platform ground-contact collision dangerous area; s200, the arm support inclination angle and the arm support length information of the overhead working truck are collected in real time; s300, calculating the real-time working amplitude of the overhead working truck and the height of a working platform, and judging the boom state at the current moment; and S400, according to the real-time operation amplitude and the height of the aerial work platform, whether the working platform is located in a ground contact collision dangerous area or not is judged. The risk that the working platform collides with the ground in a set area can be effectively avoided, the problem that the working platform touches the ground and collides in the working process of the overhead working truck platform is solved through an intelligent and preventive control strategy, the working safety, efficiency and equipment durability are improved, and the working efficiency is improved. The use requirements of the insulated overhead working truck and the working platform thereof are met, the cost is reduced, and the flexibility is improved.

Description

Technical Field

[0001] The invention relates to the field of aerial work vehicles, and in particular to a method for preventing a platform of an aerial work vehicle from touching the ground and colliding with the ground. Background Art

[0002] During the construction process of aerial work vehicles, the working environment is complex, and various accidents caused by collisions of aerial work platforms are increasing, causing serious harm to personal safety and public property. Since the existing aerial work vehicles lack anti-collision safety control systems, when the staff operate the aerial work vehicle platform, if they are not focused or only one person is operating, they cannot conduct a full-scale observation. When the amplitude change angle is small, the work platform may collide with the ground, resulting in a high frequency of accidents, low work reliability, and poor efficiency. The original aerial work vehicles mainly avoid collisions between the work platform and the ground through observation and reminders by relevant personnel on site, but this method is inefficient, and there may be a risk of collision when human eyes cannot observe in place, affecting the safety and reliability of aerial work.

[0003] The existing aerial work vehicles are equipped with anti-collision devices, which generally include: adding radars, probes, or using three-dimensional laser scanning and other methods. However, due to the overly complex structure of this device, the radar and probe also need to be installed at multiple points and angles, so at present, this anti-collision device is difficult to use in actual construction. At the same time, when the arm amplitude angle is small and the arm length is long, the arm will undergo flexible deformation, and the existing method will cause certain deviations and lead to measurement deviations.

[0004] In view of this, how to design a method for preventing an aerial work vehicle platform from touching the ground and colliding with the ground to overcome the defects in the above-mentioned prior art is a technical problem that needs to be solved urgently by those skilled in the art.

[0005] Existing technologies such as patent CN208603611U propose an anti-collision device for aerial work vehicles, which has the following characteristics: if there is an obstacle, the sensor in the sensing device will detect it using the ultrasonic wave emitted by the acoustic resonator, the sensor will sense it, and the sensor will transmit the sound wave to the sound wave receiver, the sound wave receiver will feed the sound wave back to the data converter, the data converter will convert the sound wave into a signal, and then send the signal to the signal transmitter, and then the signal transmitter will send the signal to the controller, the controller will control the connection main frame to stop automatically, and then the operator can make adjustments in the operating room, thereby preventing the main frame from colliding with the obstacle and causing safety problems.

[0006] However, although the patent can predict the distance between the aerial work vehicle and obstacles in advance by setting up a radar system, it is necessary to set up a protective frame outside the vehicle body, and ultrasonic probes must be installed on all sides of the protective frame. The anti-collision device of the aerial work vehicle is installed in a fixed position and lacks flexibility in use. It is only suitable for the anti-collision of general non-insulated aerial work vehicles and cannot guarantee the insulation performance of the working platform of insulated aerial work vehicles. At the same time, the device adds a series of devices such as ultrasonic sensors, which increases the cost of use.

[0007] Existing technologies such as the anti-collision device for aerial work platforms proposed in patent CN201665512U are characterized in that the device includes a platform display, an operating table, a control valve block, a controller, an ultrasonic sensor, a right-angle iron, an iron plate and a buzzer. The operating table and the control valve block are fixed on the aerial work platform, the display and the buzzer are installed on the operating table, the controller is installed in the operating table, the right-angle iron is fixed to the front end of the bottom of the aerial work platform, the iron plate is fixed to both sides of the bottom of the aerial work platform, there are six ultrasonic sensors, four of which are installed on the right-angle iron of the aerial work platform, and two are installed on the iron plates on both sides of the aerial work platform. The platform display, operating table, control valve block and ultrasonic sensor are all electrically connected to the controller. The monitoring range of the ultrasonic sensor can cover the entire platform below, which can prevent the work platform from colliding with other objects at high altitude.

[0008] However, the patent also requires the installation of ultrasonic sensors during use, and there are six ultrasonic sensors in total. The installation of ultrasonic sensors also increases the cost of use and maintenance. The right-angle iron is a conductor and cannot be installed in an insulating platform. Therefore, the patent is not suitable for anti-collision of insulated aerial work vehicles.

[0009] Existing technologies such as patent CN203865993U propose an anti-collision structure for an aerial work platform, which is characterized by: an anti-collision frame is set at the bottom of the work platform through a steel rope, a torsion spring is installed between the anti-collision frame and the bottom of the work platform, two annular magnetic coils are installed at the bottom of the work platform, and a proximity switch corresponding to the annular magnetic coil is installed on the anti-collision frame, and the proximity switch is located on the vertical line where the center of the annular magnetic circle is located. The proximity switch is connected to the control room of the work platform to stop the work platform from moving, thereby preventing the aerial work platform from colliding with obstacles and protecting the personal safety of the operator. The short side length of the anti-collision frame is greater than the long side length of the work platform to ensure that the plane area of ​​the anti-collision frame is greater than the plane area of ​​the work platform, so that it can make an early warning and provide buffer time for the braking of the work platform.

[0010] However, the anti-collision frame in the patent is connected to the working platform through steel ropes, and needs to be installed with springs and proximity switches. Installing more devices will greatly increase the equipment redundancy of the aerial work platform, thereby increasing the manufacturing and maintenance costs. Therefore, this solution is not economical. The anti-collision structure described in the patent needs to be fixedly installed and cannot achieve automatic and flexible processing, and has poor flexibility.

[0011] Therefore, it is necessary to specifically design a new method for preventing aerial work vehicle platforms from touching the ground and colliding with the ground to meet the use needs of insulated aerial work vehicles and their work platforms, reduce costs and improve flexibility. Summary of the invention

[0012] Purpose of the invention: In view of the shortcomings and defects of the prior art, the present invention provides a method for preventing an aerial work vehicle platform from touching the ground and colliding with the ground, which can effectively avoid the risk of the working platform colliding with the ground in a set area. Through an intelligent and preventive control strategy, the problem of ground collision that may occur during the operation of the aerial work vehicle platform is solved, the operation safety, efficiency and equipment durability are improved, the use needs of insulated aerial work vehicles and their working platforms are met, costs are reduced and flexibility is improved.

[0013] Technical solution: A method for preventing a platform of an aerial work vehicle from touching the ground and colliding with the ground is characterized by comprising the following steps:

[0014] S100, setting relevant parameters for preventing the working platform from touching the ground and collision, and defining a dangerous area for the platform to touch the ground and collision;

[0015] S200, real-time collection of boom inclination angle and boom length information of the aerial work vehicle;

[0016] S300, calculating the real-time operating range and working platform height of the aerial work vehicle, and determining the boom state at the current moment;

[0017] S400, judging whether the working platform is in a ground collision danger zone according to the real-time working range and the height of the aerial working platform: if so, controlling the working platform to slow down or stop moving in the dangerous direction; if not, controlling the working platform to continue to move normally.

[0018] Wherein, in the step S100, setting the relevant parameters of the working platform to prevent ground collision includes the following steps:

[0019] S101, setting the minimum ground protection amplitude X0 and the maximum ground protection amplitude X1;

[0020] S102, respectively setting a stop height Y0 corresponding to the minimum ground protection range and a stop height Y1 corresponding to the maximum ground protection range;

[0021] S103, setting the platform height corresponding to the start of deceleration when the maximum amplitude of anti-touchdown is reached, and calculating the height difference Δh from deceleration to stop corresponding to the maximum amplitude;

[0022] S104, using the stop height Y0 corresponding to the minimum ground-proof amplitude X0 as the lower limit and the stop height Y1 corresponding to the maximum ground-proof amplitude X1 as the upper limit, linearly interpolate the stop height within the limited amplitude range and take Δh as the height difference from deceleration to stop.

[0023] Among them, in the step S101, the minimum ground protection amplitude X0 and the maximum ground protection amplitude X1 are initially configured through on-site calibration of the display or through the program to define the amplitude range corresponding to the ground collision risk area of ​​the working platform.

[0024] Among them, in the step S102, the stop height Y0 corresponding to the minimum ground protection amplitude X0 and the stop height Y1 corresponding to the maximum ground protection amplitude X1 are respectively set by on-site calibration of the display or by program configuration.

[0025] Among them, in the step S200, the inclination angle and length information of the boom of the aerial work vehicle are collected in real time through the inclination sensor and the length sensor. The inclination sensor obtains the inclination angle α of the boom and sends it to the controller, and the length sensor obtains the working length L of the boom and sends it to the controller.

[0026] Among them, in the step S300, the controller calculates the real-time operating range of the aerial work vehicle and the height of the working platform through the information collected by the sensor.

[0027] Among them, the controller obtains the horizontal coordinate x and vertical coordinate y of the working platform during the movement, and generates real-time azimuth coordinates (x, y) based on the horizontal coordinate x and the vertical coordinate y; the real-time azimuth coordinates (x, y) are obtained by the controller, and the real-time azimuth coordinates (x, y) can reflect the real-time position of the working platform, so that the controller can detect the real-time position of the working platform.

[0028] Wherein, the arm comprises a retractable arm structure rotatably arranged on a chassis; and the working platform is arranged at the end of the arm.

[0029] Among them, the ground collision risk working area is the area enclosed by (X0, Y0), (X1, Y1), (X0, 0), and (X1, 0). In the non-ground collision risk working area, the aerial work vehicle working platform will not collide with the ground. Next, the aerial work vehicle is controlled to work, and the real-time azimuth coordinates of the working platform are obtained during the movement of the working platform, and the real-time position of the working platform is recorded. Then, the real-time position of the working platform is compared with the ground collision risk working area, that is, whether the working platform is close to the ground collision risk working area is judged according to the real-time azimuth coordinates. When the working platform is not about to approach the ground collision risk working area, the working platform moves according to normal control. When the working platform is about to approach the ground collision risk working area, the working platform is controlled to stop moving to the ground collision risk working area, thereby effectively avoiding the risk of collision between the working platform and the ground.

[0030] Aerial work vehicle using platform anti-ground collision method.

[0031] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0032] Improve operation safety: This solution effectively avoids collisions between the platform and the ground or obstacles through real-time monitoring and intelligent control of the movement of the aerial work vehicle platform, significantly reduces safety risks during the operation, provides a safer working environment for operators, and ensures their life safety.

[0033] Improve work efficiency: By precisely controlling the moving direction and speed of the work platform, this solution reduces the time wasted on adjusting positions or dealing with collision accidents, allowing aerial work to be carried out more smoothly and efficiently, thereby speeding up the work progress and improving overall work efficiency.

[0034] Extending the service life of equipment: This solution effectively avoids physical damage to the working platform caused by collision, reduces the need for repair and replacement, and thus significantly extends the service life of the equipment. This not only reduces the company's equipment maintenance costs, but also improves the use value of the equipment, bringing long-term economic benefits to the company.

[0035] Enhanced operational flexibility: This solution is applicable to various complex operating environments. Through intelligent control, the operating platform can flexibly respond to different terrains and obstacles, improving the convenience of operation for operators. This flexibility enables aerial operations to better adapt to diverse operational needs and improves operational flexibility and efficiency.

[0036] Reduce accident risks: This solution effectively prevents the occurrence of work platform collision accidents, significantly reducing the losses and compensation caused by accidents such as electric shock. This not only reduces the legal liability risks and economic burden of enterprises, but also protects the safety of the surrounding environment and residents. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a flow chart of the present invention;

[0038] Figure 2 It is a structural schematic diagram of the present invention;

[0039] In the figure, 10 is a chassis; 20 is a boom; and 30 is a working platform. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0041] like Figure 1 A method for preventing a platform of an aerial work vehicle from touching the ground and colliding with the ground comprises the following steps:

[0042] S100, setting relevant parameters for preventing the working platform from touching the ground and collision, and defining a danger zone for the platform touching the ground and collision.

[0043] S101, setting the minimum ground protection amplitude X0 and the maximum ground protection amplitude X1. The minimum ground protection amplitude X0 and the maximum ground protection amplitude X1 are initially configured through the display on-site calibration or through the program to define the amplitude range corresponding to the ground collision risk area of ​​the working platform.

[0044] S102, respectively set the stop height Y0 corresponding to the minimum anti-touchdown amplitude and the stop height Y1 corresponding to the maximum anti-touchdown amplitude. Set the stop height Y0 corresponding to the minimum anti-touchdown amplitude X0 and the stop height Y1 corresponding to the maximum anti-touchdown amplitude X1 respectively through on-site calibration of the display or through program configuration.

[0045] S103, setting the platform height corresponding to the start of deceleration when the anti-touchdown amplitude is the maximum, and calculating the height difference Δh from deceleration to stop corresponding to the maximum amplitude.

[0046] S104, using the stop height Y0 corresponding to the minimum ground-proof amplitude X0 as the lower limit and the stop height Y1 corresponding to the maximum ground-proof amplitude X1 as the upper limit, linearly interpolate the stop height within the limited amplitude range and take Δh as the height difference from deceleration to stop.

[0047] S200, real-time acquisition of the inclination angle and length information of the boom 20 of the aerial work vehicle. The inclination angle and length information of the boom 20 of the aerial work vehicle are acquired in real time through the inclination sensor and the length sensor. The inclination sensor acquires the inclination angle α of the boom 20 and sends it to the controller, and the length sensor acquires the working length L of the boom 20 and sends it to the controller.

[0048] Optionally, in step S200, the arm length sensor and the main arm inclination sensor can also be replaced by a long angle sensor of the length and angle of the arm 20, and the positions of the arm 20 and the working platform 30 can be determined by the monitoring data of the long angle sensor, and whether the working platform 30 is in a dangerous position of touching the ground can be determined by the monitoring data of the long angle sensor.

[0049] Optionally, various data monitoring mechanisms (including but not limited to length sensors, angle sensors) used for detecting the amplitude and height of the aerial work vehicle and the work platform, as well as driving mechanisms of corresponding components of the aerial work vehicle, are connected to the controller through a CAN bus to achieve information exchange and ensure the real-time and stability of communication.

[0050] The controller obtains the working length L of the boom 20 and the inclination angle α of the boom 20 relative to the horizontal plane. The principle and specific process of the controller obtaining the horizontal coordinate x and the vertical coordinate y according to the working length L of the boom 20 and the inclination angle α of the boom 20 relative to the horizontal plane are prior arts and will not be elaborated here.

[0051] S300, calculate the real-time operating range and working platform height of the aerial work vehicle, and determine the boom state at the current moment. The controller calculates the real-time operating range of the aerial work vehicle and the height of the working platform 30 through the information collected by the sensor. The controller obtains the horizontal coordinate x and the vertical coordinate y of the working platform 30 during the movement, and generates the real-time azimuth coordinate (x, y) according to the horizontal coordinate x and the vertical coordinate y; the real-time azimuth coordinate (x, y) is obtained by the controller, and the real-time azimuth coordinate (x, y) can reflect the real-time position of the working platform 30, so that the controller can detect the real-time position of the working platform (30).

[0052] S400, judging whether the working platform 30 is in a ground collision danger zone according to the real-time working range and the height of the aerial working platform: if so, controlling the working platform 30 to slow down or stop moving in the dangerous direction; if not, controlling the working platform 30 to continue to move normally.

[0053] like Figure 2 The boom 20 includes a retractable boom structure rotatably disposed on the chassis 10 ; the working platform 30 is disposed at the end of the boom 20 .

[0054] The ground collision risk working area is an area enclosed by (X0, Y0), (X1, Y1), (X0, 0), and (X1, 0). In the non-ground collision risk working area, the aerial work vehicle working platform 30 will not collide with the ground. Next, the aerial work vehicle is controlled to work, and the real-time azimuth coordinates of the working platform 30 are obtained during the movement of the working platform 30, and the real-time position of the working platform 30 is recorded. Then, the real-time position of the working platform 30 is compared with the ground collision risk working area, that is, whether the working platform 30 is close to the ground collision risk working area is judged according to the real-time azimuth coordinates. When the working platform 30 is not about to approach the ground collision risk working area, the working platform 30 moves according to normal control. When the working platform 30 is about to approach the ground collision risk working area, the working platform 30 is controlled to stop moving to the ground collision risk working area, thereby effectively avoiding the risk of collision between the working platform 30 and the ground, and ensuring the safety and reliability of the aerial work process.

[0055] The innovation of the present invention is as follows: 1. Delineation of anti-ground collision area: By setting the minimum amplitude (X0) and maximum amplitude (X1) of anti-ground collision, the dangerous area of ​​ground collision of the working platform is delineated, which is an important prerequisite for preventing the platform from accidentally touching the ground during operation. 2. Real-time boom posture calculation: The inclination angle and arm length of the aerial work vehicle are collected in real time by using the inclination sensor and the length sensor, that is, the data collection and processing are completed by the original electrical components and controller of the aerial work vehicle. The controller calculates the real-time operation amplitude and the height of the working platform based on the sensor data, which is the basis for dynamic monitoring and timely response. 3. Intelligent judgment and response: According to the real-time operation amplitude and platform height, it is intelligently judged whether the platform enters the ground collision danger zone. Once it is judged that the platform is in the danger zone, the working platform is immediately controlled to slow down or stop moving in the dangerous direction to avoid ground collision. 4. Calculation and linear interpolation of the height difference from deceleration to stop: The platform height corresponding to the maximum amplitude of anti-ground collision is set, and the height difference (Δh) required for deceleration to stop is calculated. Within the limited amplitude range, the stop height is linearly interpolated to ensure that the platform can decelerate and eventually stop at an appropriate speed under different amplitudes to prevent it from touching the ground.

[0056] The work platform plays a vital role as a safety barrier in aerial work. Through the implementation of the present invention, it can be ensured that the platform always maintains a safe distance during the operation process. When the aerial work vehicle is operating, especially when the platform is close to the ground, there is a high risk of touching the ground and colliding. The present invention effectively avoids the platform touching the ground and colliding due to improper operation or misjudgment through real-time monitoring and early warning, thereby significantly improving the safety of the operators. By integrating intelligent devices such as inclination sensors, length sensors and controllers, real-time monitoring and calculation of the boom status (such as inclination, length) of the aerial work vehicle is realized. The boom calculation can more accurately determine the platform position, avoiding measurement errors caused by flexible deformation of the boom, and then intelligently controlling the movement of the work platform according to the calculation results, realizing the automation and intelligence of the operation process.

[0057] The present invention provides an anti-ground collision solution for specially configured aerial work vehicles, especially insulated work platforms, without adding additional components containing non-insulating materials such as metal, and can ensure the insulation performance of the insulating platform. At the same time, the insulating platform is usually made of high-performance insulating materials. This solution avoids direct contact between the platform and the ground, thereby reducing the damage to the insulating material that may be caused by the collision, and further enhancing the insulation protection capability of the insulating platform. Different from the traditional post-collision protection mechanism, the present invention adopts a preventive protection strategy, that is, before the work platform enters the ground collision danger zone, it calculates and judges and takes corresponding deceleration or stopping measures, effectively preventing the occurrence of collision accidents. By precisely controlling the movement of the work platform, time and resources wasted due to frequent position adjustments or handling of collision accidents are avoided, thereby improving the overall work efficiency. It can reduce equipment damage caused by collisions, extend the service life of aerial work vehicles and their key components, and reduce maintenance costs.

Claims

1. A method for preventing a platform of an aerial work vehicle from touching the ground and colliding with the ground, characterized in that: The steps include: S100, setting relevant parameters for preventing the working platform from touching the ground and collision, and defining a dangerous area for the platform to touch the ground and collision; S200, collecting information on the inclination angle and length of the boom (20) of the aerial work vehicle in real time; S300, calculating the real-time operating range and working platform height of the aerial work vehicle, and determining the boom state at the current moment; S400, judging whether the working platform (30) is in a ground collision danger zone according to the real-time working range and the height of the aerial working platform: if so, controlling the working platform (30) to slow down or stop moving in the dangerous direction; if not, controlling the working platform (30) to continue to move normally.

2. The method for preventing the aerial work vehicle platform from touching the ground and colliding with the ground according to claim 1, characterized in that: In the step S100, setting the relevant parameters of the working platform to prevent ground collision includes the following steps: S101, setting the minimum ground protection amplitude X0 and the maximum ground protection amplitude X1; S102, respectively setting a stop height Y0 corresponding to the minimum ground protection range and a stop height Y1 corresponding to the maximum ground protection range; S103, setting the platform height corresponding to the start of deceleration when the maximum amplitude of anti-touchdown is reached, and calculating the height difference Δh from deceleration to stop corresponding to the maximum amplitude; S104, using the stop height Y0 corresponding to the minimum ground-proof amplitude X0 as the lower limit and the stop height Y1 corresponding to the maximum ground-proof amplitude X1 as the upper limit, linearly interpolate the stop height within the limited amplitude range and take Δh as the height difference from deceleration to stop.

3. The method for preventing the aerial work vehicle platform from touching the ground and colliding with the ground according to claim 2, characterized in that: In the step S101, the minimum ground protection amplitude X0 and the maximum ground protection amplitude X1 are initially configured through on-site calibration of a display or through a program to define an amplitude range corresponding to the ground collision risk area of ​​the working platform.

4. The method for preventing the aerial work vehicle platform from touching the ground and colliding with the ground according to claim 3, characterized in that: In the step S102, the stop height Y0 corresponding to the minimum ground protection amplitude X0 and the stop height Y1 corresponding to the maximum ground protection amplitude X1 are respectively set by on-site calibration of the display or by program configuration.

5. The method for preventing the aerial work vehicle platform from touching the ground and colliding with the ground according to claim 1, characterized in that: In the step S200, the inclination angle and the length information of the boom (20) of the aerial work vehicle are collected in real time by means of an inclination sensor and a length sensor. The inclination angle α of the boom (20) is acquired by the inclination sensor and sent to a controller. The working length L of the boom (20) is acquired by the length sensor and sent to the controller.

6. The method for preventing the aerial work vehicle platform from touching the ground and colliding with the ground according to claim 5, characterized in that: In step S300, the controller calculates the real-time operating range of the aerial work vehicle and the height of the working platform (30) through information collected by the sensor.

7. The method for preventing the aerial work vehicle platform from touching the ground and colliding with the ground according to claim 6, characterized in that: The controller obtains the horizontal coordinate x and the vertical coordinate y of the working platform (30) during the movement, and generates real-time azimuth coordinates (x, y) based on the horizontal coordinate x and the vertical coordinate y; the real-time azimuth coordinates (x, y) are obtained by the controller, and the real-time azimuth coordinates (x, y) can reflect the real-time position of the working platform (30), thereby enabling the controller to detect the real-time position of the working platform (30).

8. The method for preventing aerial work vehicle platform from touching the ground and collision according to claim 7, characterized in that: The arm (20) comprises a telescopic arm structure rotatably arranged on a chassis (10); the working platform (30) is arranged at the end of the arm (20).

9. The method for preventing the aerial work vehicle platform from touching the ground and colliding with the ground according to claim 8, characterized in that: The ground contact collision danger working area is an area enclosed by (X0, Y0), (X1, Y1), (X0, 0), and (X1, 0). In the non-ground contact collision danger working area, the aerial work vehicle working platform (30) will not collide with the ground. Next, the aerial work vehicle is controlled to work, and the real-time azimuth coordinates of the working platform (30) are obtained during the movement of the working platform (30), and the real-time position of the working platform (30) is recorded. Then, the real-time position of the working platform (30) is compared with the ground contact collision danger working area, that is, whether the working platform (30) is close to the ground contact collision danger working area is determined based on the real-time azimuth coordinates. When the working platform (30) is not about to approach the ground contact collision danger working area, the working platform (30) moves in accordance with normal control. When the working platform (30) is about to approach the ground contact collision danger working area, the working platform (30) is controlled to stop moving toward the ground contact collision danger working area, thereby effectively avoiding the risk of the working platform (30) colliding with the ground.

10. An aerial work vehicle using the platform ground collision prevention method as claimed in any one of claims 1 to 9.

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