Accurate positioning method based on variable-frequency brake motor mechanical arm

Abstract

The invention provides a precise positioning method based on a variable-frequency brake motor mechanical arm. The precise positioning method comprises the following steps that S1, an x-y-z space rectangular coordinate system is set with the mechanical arm as the original point; s2, a target position is set for the mechanical arm; s3, the variable-frequency brake motor calculates the rotating speed and the number of turns of the variable-frequency brake motor according to the difference value between the target position and the initial position of the mechanical arm; s4, the motor starts to start according to the set rotating speed, the set number of turns and the set positioning algorithm; s5, the mechanical arm reaches the target position, the goods are grabbed, and the goods are moved to the designated position; according to the variable-frequency brake motor, an accurate positioning method is provided for the mechanical arm, errors of the mechanical arm in the moving process are reduced, and accurate grabbing and placing of goods can be achieved; and meanwhile, the mechanical arm can flexibly move between a narrow storage channel and a goods shelf, and the precise positioning capability of the mechanical arm enables the mechanical arm to adapt to warehouse environments with different layouts.

Description

Technical Field

[0001] The present invention relates to the field of variable frequency brake motors, and in particular to a precise positioning method based on variable frequency brake motors. Background Art

[0002] In warehousing and logistics, the precise positioning of robotic arms has a wide range of applications with great potential. The operator can accurately position the robotic arm to the storage location of the goods, whether on a shelf or in a specific area of ​​the warehouse. This means that it can quickly grab the goods and move them to the designated location, reducing the time spent searching for the goods.

[0003] But there are also the following problems: 1. During the movement of the robot arm, the speed and stability are often not adjustable. When the robot arm moves goods, the goods may be damaged or the accuracy of the robot arm positioning may be reduced; 2. The robot arm is easily affected by external forces during movement, causing the robot arm to deviate from its original trajectory, thereby reducing the accuracy of the robot arm's positioning; 3. When the robotic arm is moving goods, the output power is often constant when facing different goods. It cannot flexibly adjust the output power according to the quality of the goods, which increases energy consumption. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a precise positioning method based on a variable frequency brake motor.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A precise positioning method based on a variable frequency brake motor comprises the following steps: S1: The operator sets the xyz space rectangular coordinate system with the robot base as the origin; The mechanical arm includes a variable frequency brake motor, a control system, and a position sensor; The variable frequency brake motor includes a counting sensor and a rotor, and the variable frequency brake motor provides power for the mechanical arm; The control system controls the voltage frequency of the variable frequency brake motor; The initial position of the robot base is (0,0,0); The position sensor is used to collect the real-time position (x, y, z) of the robotic arm; S2: The operator sets the target position to be reached by the robot arm in the operating system; The target position is a point in the xyz space rectangular coordinate system, marked as (X1, Y1, Z1); S3: The operating system determines the speed and number of turns of the variable frequency brake motor according to the distance S between the target position and the initial position of the robot arm; The following sub-steps are included: S31: The operating system calculates the difference between the target position and the initial position of the robot arm in the X-axis, Y-axis and Z-axis; The difference of the X axis = X1-0, the difference of the Y axis = Y1-0, and the difference of the Z axis = Z1-0; S32: The operating system calculates the angle a and the distance S between the initial position and the target position according to the difference between the target position and the initial position of the robot arm on the X-axis, Y-axis and Z-axis; First, the distance S from the initial position to the target position is calculated according to the distance function; Distance S= ; Then, according to the relative position relationship between the initial position and the target position, the angle a of the target position relative to the initial position is calculated; Said ; S33: the operating system calculates the number of revolutions p of the variable frequency brake motor according to the determined distance; The distance that the mechanical arm moves when the variable frequency brake motor rotates one circle is M; The distance M is measured by a position sensor; The number of turns P=S / M; S34: the operator sets the corresponding speed G1 of the variable frequency brake motor in the operating system according to the distance S, and divides the speed G1 change process into a starting stage, a constant speed stage, and a deceleration stage; The specific content of step S34 is: S341: The variable frequency brake motor identifies the real-time number of turns of the variable frequency brake motor; A sensor is provided on the top of the variable frequency brake motor, and the sensor monitors the real-time number of turns of the variable frequency brake motor in real time; S342: The operating system is divided into a starting stage, a constant speed stage, and a deceleration stage according to the number of rotations P of the variable frequency brake motor; The starting stage is the first 20% of the number of rotations P. In the starting stage, the speed of the variable frequency brake motor starts from 0 and increases uniformly to G1 according to a certain acceleration k; The quantitative relationship between the speed G1, the rotor rotation time t1 and the rotor acceleration k is G1=△G+G0, where △G is the speed change, △G=kt1; G0 is the initial speed, and the initial speed is 0, that is, G1=kt1, t1=G1 / k; The value of the acceleration k is a constant; The value of acceleration k can be calculated according to formula 1; Formula 1: , k is acceleration, t1 is the time required for the speed to reach the set speed G1, dt is a small increment of time t, and P is the total number of revolutions of the rotor; Therefore, by inputting the set speed G1 and acceleration k into the control system, the speed of the variable frequency brake motor can be controlled to reach the set speed G1 when the real-time number of turns of the variable frequency brake motor reaches 20% of the total number of turns; The uniform speed stage is the first 20%-80% of the number of rotations P. During the uniform speed stage, the speed G1 of the variable frequency brake motor remains unchanged. The duration of the uniform speed stage is t2, where t2=60%P / G1, p is the total number of rotations, and G1 is the set speed; The deceleration stage is the number of rotations P80%-100%. In the deceleration stage, the speed of the variable frequency brake motor is uniformly reduced to the threshold value A; The calculation formula for uniform speed reduction is G= G1-k (t-t1-t2), where t is the time for the rotor to rotate, t1 is the time required for the speed G to reach the set speed G1, t2 is the duration of the uniform speed stage, t-t1-t2 is the duration of the deceleration stage, G is the speed, G1 is the set speed, and k is the acceleration; The threshold value A is the rotation speed at which the rotor can be immediately stopped by the braking device.

[0006] S4: The variable frequency brake motor starts to start according to the preset positioning algorithm based on the set speed G1 and the number of turns P that the variable frequency brake motor needs to rotate; The specific contents of the positioning algorithm are as follows: Establish perpendicular constraints from point to plane; The equation of a plane is ax + by + cz + d = 0; The coefficients a, b, and c form an array, representing the normal vector of the plane; Convert the target position point into an array (X1, Y1, Z1) to represent the point vector; The plane plane is perpendicular to the straight line where the target position and the initial position are located; Calculate the dot product of the point vector and the normal vector plus the constant term d in the plane equation. Dot product N=X1a+Y1b+Z1c+d. If the absolute value of dot product N is less than the threshold value B, it means that the target position is perpendicular to the plane, and dot product N returns the F(x, y, z) constraint equation group. If the absolute value of dot product N is greater than the threshold value B, it means that the target position is not perpendicular to the plane, and dot product N does not return the F(x, y, z) constraint equation group. The threshold value B is a value close to 0; Create a distance constraint: The operating system measures a distance Q between the target position and the initial position according to the position sensor; Determine whether the distance Q between the target position and the initial position is equal to the distance S. If Q=S, return the F(x, y, z) constraint equation group. If Q≠S, do not return the F(x, y, z) constraint equation group. Combine these two constraints into a constraint equation set F(x, y, z) and return; The F(x, y, z) constraint equations are

[0007] Establish the Jacobian matrix J of the constraint equations; The elements of the Jacobian matrix J are approximated by making a small perturbation to each variable x, y, and z, increasing dx, dy, and dz respectively, and then calculating the ratio of the change in the function value to the perturbation value; The Jacobian matrix J is

[0008] The dx, dy, and dz are respectively small changes of x, y, and z, and dx, dy, and dz are 0.00001; The Newton-Raphson method is used to iteratively derive the position of the predetermined point based on the current point position and the advancing direction; The position of the predetermined point is the position point where the robot arm finally stops, which is deduced by the operating system based on the current position and forward direction of the robot arm; Set the initial point to (0,0,0), and according to the position of the robot arm (x, y, z), substitute the value of (x, y, z) into the F (x, y, z) constraint equation group and Jacobian matrix J; Set the maximum number of iterations MAX, and bring the values ​​of the F(x, y, z) constraint equation group and the Jacobian matrix J obtained above into the iterative formula, which is: vec(x, y, z) n+1 =vec(x,y,z) n – J*(-1)[vec(x,y,z) n 】*vec(F)

vec(x,y,z) n

vec(x, y, z) n

vec(x, y, z) n

[0009] S5: The robotic arm reaches the target position, grabs the goods, and moves the goods to the designated position.

[0010] The specific content of step S5 is: S51: The robotic arm reaches the target position and grabs the goods with the corresponding power output according to the mass of the goods; A weighing device is provided at the end of the robotic arm, which can accurately weigh the mass of the grabbed goods; When the robotic arm touches the goods, it judges the mass m of the goods, and the motor outputs the corresponding power L according to the mass of the goods; The power L can ensure that the robotic arm firmly grabs the goods.

[0011] S52: The robotic arm transports the goods to the designated position.

[0012] Compared with the prior art, the beneficial effects of the present invention are: The method proposed by the present invention can increase the ability of the robotic arm to accurately grab goods and accurately control the speed and angle of the robotic arm; Compared with the prior art, the beneficial effects of the present invention are as follows: the method proposed by the present invention can increase the ability of the robot arm to accurately grasp goods and accurately control the speed and angle of the robot arm; The variable frequency brake motor proposed in the present invention can adjust the power output according to the actual demand of the goods. When the robot arm grabs the goods, the load at different stages is different. This characteristic of adaptively adjusting the power according to the load avoids the energy waste of the motor when high power is not needed, improves energy utilization, and reduces operating costs.

[0013] According to the method proposed by the present invention, the variable frequency brake motor can achieve wide range speed regulation by changing the power supply frequency. When the robot arm grabs goods, different task scenarios may require different movement speeds. For example, when grabbing goods that are far away and the time requirement is not particularly urgent, a lower speed can be used to allow the robot arm to approach the goods smoothly; in scenarios that require rapid response, such as grabbing small goods that are transported at high speed on an assembly line, the speed can be increased to quickly reach the target position. This wide range of speed regulation capabilities enables the robot arm to adapt to the grabbing needs of a variety of goods, improving work efficiency and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart of the steps of the precise positioning method based on the variable frequency brake motor of the present invention; DETAILED DESCRIPTION

[0015] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the following detailed description is given in conjunction with the embodiments.

[0016] like Figure 1 As shown, the precise positioning method based on the variable frequency brake motor includes the following steps: S1: The operator sets the xyz space rectangular coordinate system with the robot base as the origin; The mechanical arm includes a variable frequency brake motor, a control system, and a position sensor; The variable frequency brake motor includes a counting sensor and a rotor, and the variable frequency brake motor provides power for the mechanical arm; The control system controls the voltage frequency of the variable frequency brake motor; The xyz space rectangular coordinate system takes the robot arm base as the origin and can mark any point in the three-dimensional space; The operating system controls the speed G of the variable frequency brake motor by controlling the voltage frequency, and the speed of the variable frequency motor is determined by the received voltage frequency.

[0017] S2: The operator sets the target position to be reached by the robot arm in the operating system; The target position is a point in the xyz space rectangular coordinate system, marked as (X1, Y1, Z1); The target location is the location of the goods; S3: The operating system determines the speed G1 and the number of turns P of the variable frequency brake motor according to the distance S between the target position and the initial position of the robot arm; The following sub-steps are included: S31: The operating system calculates the difference between the target position and the initial position of the robot arm in the X-axis, Y-axis and Z-axis; The difference of the X axis = X1-0, the difference of the Y axis = Y1-0, and the difference of the Z axis = Z1-0; S32: The operating system calculates the angle a and the distance S between the initial position and the target position according to the difference between the target position and the initial position of the robot arm on the X-axis, Y-axis and Z-axis; First, the distance S from the initial position to the target position is calculated according to the distance function; Distance S= ; Then, according to the relative position relationship between the initial position and the target position, the angle a of the target position relative to the initial position is calculated; Said ; S33: the operating system calculates the number of revolutions p of the variable frequency brake motor according to the determined distance; The distance that the mechanical arm moves when the variable frequency brake motor rotates one circle is M; The distance M is measured by a position sensor; The number of turns P=S / M; By calculating the quotient of the distance S and the distance M, the number of turns P that the rotor needs to make is obtained; S34: the operator sets the corresponding speed G1 of the variable frequency brake motor in the operating system according to the distance S, and divides the speed G1 change process into a starting stage, a constant speed stage, and a deceleration stage; The specific content of step S34 is: S341: The variable frequency brake motor identifies the real-time number of turns of the variable frequency brake motor; A counting sensor is provided on the top of the variable frequency brake motor, and the sensor monitors the real-time number of turns of the variable frequency brake motor in real time; S342: The operating system is divided into a starting stage, a constant speed stage, and a deceleration stage according to the number of rotations P of the variable frequency brake motor; The starting stage is the first 20% of the number of rotations P. In the starting stage, the speed of the variable frequency brake motor starts from 0 and increases uniformly to G1 according to a certain acceleration k; The quantitative relationship between the speed G1, the rotor rotation time t1 and the rotor acceleration k is G1=△G+G0, where △G is the speed change, △G=kt1; G0 is the initial speed, and the initial speed is 0, that is, G1=kt1, t1=G1 / k; The operator adjusts the speed of the robot arm movement by setting an appropriate rotation speed G1 according to the calculated distance S and the actual usage environment to meet the robot arm movement speed required in different task scenarios.

[0018] The value of k can be calculated according to formula 1: Formula 1: , k is acceleration, t1 is the time required for the speed G to reach the set speed G1, dt is a small increment of time t, and P is the total number of revolutions of the rotor; Therefore, by inputting the set speed G1 and acceleration k into the control system, the speed of the variable frequency brake motor can be controlled to reach the set speed G1 when the real-time number of turns of the variable frequency brake motor reaches 20% of the total number of turns; The uniform speed stage is the first 20%-80% of the number of rotations P. During the uniform speed stage, the speed G1 of the variable frequency brake motor remains unchanged. The duration of the uniform speed stage is t2, where t2=60%P / G1, p is the total number of rotations, and G1 is the set speed; The deceleration stage is the number of rotations P80%-100%. In the deceleration stage, the speed of the variable frequency brake motor is uniformly reduced to the threshold value A; The calculation formula for uniform speed reduction is G= G1-k (t-t1-t2), where t is the time for the rotor to rotate, t1 is the time required for the speed G to reach the set speed G1, t2 is the duration of the uniform speed stage, t-t1-t2 is the duration of the deceleration stage, G is the speed, G1 is the set speed, and k is the acceleration; The threshold value A is the rotation speed at which the rotor in the variable frequency brake motor can be immediately stopped by the brake device.

[0019] The movement process of the variable frequency brake motor speed G is divided into three stages to ensure that the rotation of the rotor is stable in each stage, further ensuring that the state of the robotic arm is stable during the movement of the robotic arm, and avoiding the reduction of accuracy due to instability during the movement of the robotic arm.

[0020] S4: The variable frequency brake motor starts according to the set speed G1 and number of turns P and the set positioning algorithm; The specific contents of the positioning algorithm are as follows: Establish perpendicular constraints from point to plane; The equation of a plane is ax + by + cz + d = 0; The coefficients a, b, and c form an array, representing the normal vector of the plane; Convert the target position point into an array (X1, Y1, Z1) to represent the point vector; The plane plane is perpendicular to the straight line where the target position and the initial position are located; Calculate the dot product of the point vector and the normal vector plus the constant term d in the plane equation. Dot product N=X1a+Y1b+Z1c+d. If the absolute value of dot product N is less than the threshold value B, it means that the target position is perpendicular to the plane, and dot product N returns the F(x, y, z) constraint equation group. If the absolute value of dot product N is greater than the threshold value B, it means that the target position is not perpendicular to the plane, and dot product N does not return the F(x, y, z) constraint equation group. The threshold value B is a value close to 0; To create a distance constraint: The operating system measures a distance Q between the target position and the initial position according to the position sensor; Determine whether the distance Q between the target position and the initial position is equal to the distance S. If Q=S, return the F(x, y, z) constraint equation group. If Q≠S, do not return the F(x, y, z) constraint equation group. Combine these two constraints into a constraint equation set F(x, y, z) and return; The F(x, y, z) constraint equations are ; Establish the Jacobian matrix J of the constraint equations; The elements of the Jacobian matrix J are approximated by making a small perturbation to each variable x, y, and z, increasing dx, dy, and dz respectively, and then calculating the ratio of the change in the function value to the perturbation value; The Jacobian matrix J is ; The dx, dy, and dz are respectively small changes of x, y, and z, and dx, dy, and dz are 0.00001; The Newton-Raphson method is used to iteratively derive the position of the predetermined point based on the current point position and the advancing direction; The position of the predetermined point is the position point where the robot arm finally stops, which is deduced by the operating system based on the current position and forward direction of the robot arm; Set the initial point to (0,0,0), and according to the position of the robot arm (x, y, z), substitute the value of (x, y, z) into the F (x, y, z) constraint equation group and Jacobian matrix J; Set the maximum number of iterations MAX, and substitute the obtained values of the constraint equations of F(x, y, z) and the Jacobian matrix J into the iterative formula, where the iterative formula is: vec(x, y, z) n+1 = vec(x, y, z) n – J*(-1)[vec(x, y, z) n * vec(F)[vec(x, y, z) n ; vec(x, y, z) n represents the vector value of the vector (x, y, z) at the nth step, and vec(x, y, z) n+1 represents the vector value of the vector (x, y, z) at the (n + 1)th step. vec(F)[vec(x, y, z) n represents the value of the vector (x, y, z) at the nth step in the equation F(x, y, z). J*(-1)[vec(x, y, z) n represents the inverse matrix of the Jacobian matrix J[vec(x, y, z) n ; Compare the obtained vec(x, y, z) n+1 with the threshold B. If vec(x, y, z) n+1 < B, the coordinate point corresponding to the obtained vec(x, y, z) n+1 is the predetermined point; if vec(x, y, z) n+1 > B, the predetermined point cannot be obtained, and the operating system reports an error; Through the positioning algorithm, during the movement of the robotic arm, the operating system, according to the current position of the robotic arm and the Newton - Raphson method, continuously iterates the position of the target point. When the position of the target point is inconsistent with the target position, the robotic arm stops moving, and at the same time the operating system reports an error. This ensures the accuracy of the robotic arm during movement.

[0021] The specific content of step S4 is as follows: S41: The robotic arm rotates its own angle by a; The robotic arm includes a rotary joint, and the robotic arm rotates by adjusting the rotary joint; The a is the included angle between the initial position and the target position; S42: The robotic arm starts to move from the initial position to the target position along the angle a; When the robot arm is moving, the position sensor collects the position points (Xn, Yn, Zn) of the robot arm in real time. According to the positioning algorithm, the control system continuously calculates the coordinates of the predetermined point. When the coordinates of the predetermined point are inconsistent with the coordinates of the target position point, the control system reports an error and the robot arm stops moving; if the coordinates of the predetermined point are consistent with the coordinates of the target position point, the robot arm continues to move.

[0022] S5: The robot arm reaches the target position, grabs the goods, and moves them to the designated location.

[0023] The specific content of step S5 is: S51: The robot arm reaches the target position and grabs the goods according to the power output corresponding to the weight of the goods; A weighing device is provided at the end of the mechanical arm, which can accurately weigh the mass of the grabbed goods; When the robot arm contacts the goods, it weighs the mass m of the goods. The relationship between the power L and the mass of the goods is L=em, where e is the constant coefficient. The motor outputs the corresponding power L according to the mass of the goods. The power L can ensure that the robotic arm can firmly grasp the goods.

[0024] S52: The robotic arm moves the cargo to the designated location.

[0025] During use, the operator first inputs the coordinate point of the target position in the control system. The control system will calculate the distance and angle between the mechanical arm position and the target position based on the coordinate point of the mechanical arm position and the target position. At this time, the operator inputs the appropriate working speed of the variable frequency brake motor according to the actual situation. The control system will calculate the time t when the speed reaches the set working speed based on the set working speed and the number of turns of the variable frequency brake motor rotor. It ensures that when the speed reaches the working speed, the number of turns of the variable frequency brake motor is 20% of the total number of turns, ensuring that the variable frequency brake motor can drive the mechanical arm to move smoothly when working, so that the mechanical arm can ensure stability during movement and is relatively stable during the speed regulation process. Smooth speed regulation can avoid vibration or position deviation caused by sudden speed changes. This stability helps to improve the accuracy of grasping and reduce the risk of goods falling or being damaged due to the shaking of the mechanical arm during grasping. ; At this time, the robot adjusts its own angle by rotating the joint so that the angle of the robot is the angle a between the target position and the robot position, and the robot starts to move. During the movement, the control system uses the positioning algorithm to collect the position of the robot in real time, and estimates the coordinates of the terminal position reached by the robot through continuous iteration. If the estimated terminal position of the robot is the same as the target position, the robot continues to move. If the estimated terminal position is different from the target position, the robot stops moving. During the movement of the robot, it may be affected by external factors, causing the direction of movement of the robot to deviate. Through this positioning algorithm, when the robot deviates, the control system will report an error and adjust the angle of the robot, thereby improving the accuracy of the robot during the movement. When the robot reaches the target position, it starts to grab the goods, and the robot starts to weigh the mass of the goods and output the corresponding power L, which reduces the energy consumption of the variable frequency brake motor.

[0026] The present invention has been described by the above-mentioned relevant embodiments, however, the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, changes and modifications made without departing from the spirit and scope of the present invention are all within the scope of patent protection of the present invention.

Claims

1. A precise positioning method based on a variable frequency brake motor mechanical arm, characterized in that: The following steps are involved: S1: The operator sets the xyz space rectangular coordinate system with the robot base as the origin; The mechanical arm includes a variable frequency brake motor, a control system, and a position sensor; The variable frequency brake motor includes a counting sensor and a rotor, and the variable frequency brake motor provides power for the mechanical arm; The control system controls the voltage frequency of the variable frequency brake motor; The position sensor is used to collect the real-time position (x, y, z) of the robotic arm; S2: The operator sets the target position to be reached by the robot arm in the operating system; The target position is a point in the xyz space rectangular coordinate system, marked as (X1, Y1, Z1); S3: The operating system determines the speed G1 and the number of turns P of the variable frequency brake motor according to the distance S between the target position and the initial position of the robot arm; The following sub-steps are included: S31: The operating system calculates the difference between the target position and the initial position of the robot arm in the X-axis, Y-axis and Z-axis; The difference of the X axis = X1-0, the difference of the Y axis = Y1-0, and the difference of the Z axis = Z1-0; S32: The operating system calculates the angle a and the distance S between the initial position and the target position according to the difference between the target position and the initial position of the robot arm on the X-axis, Y-axis and Z-axis; First, the distance S from the initial position to the target position is calculated according to the distance function; Distance S= ; Then, according to the relative position relationship between the initial position and the target position, the angle a of the target position relative to the initial position is calculated; Said ; S33: the operating system calculates the number of revolutions p of the variable frequency brake motor according to the determined distance S; The distance that the mechanical arm moves when the variable frequency brake motor rotates one circle is M; The distance M is measured by a position sensor; The number of turns P=S / M; S34: the operator sets the corresponding speed G1 of the variable frequency brake motor in the operating system according to the distance S, and divides the speed G1 change process into a starting stage, a constant speed stage, and a deceleration stage; S4: The variable frequency brake motor starts to start according to the preset positioning algorithm based on the set speed G1 and the number of turns P that the variable frequency brake motor needs to rotate; S5: The robot arm reaches the target position, grabs the goods, and moves them to the designated location.

2. The precise positioning method based on the variable frequency brake motor mechanical arm according to claim 1, characterized in that: The specific content of step S34 is: S341: The variable frequency brake motor identifies the real-time number of turns of the variable frequency brake motor; A counting sensor is provided on the top of the variable frequency brake motor, and the sensor monitors the real-time number of turns of the variable frequency brake motor in real time; S342: The operating system is divided into a starting stage, a constant speed stage, and a deceleration stage according to the number of rotations P of the variable frequency brake motor; The starting stage is the first 20% of the number of rotations P. In the starting stage, the speed of the variable frequency brake motor starts from 0 and increases uniformly to G1 according to a certain acceleration k; The quantitative relationship between the speed G1, the rotor rotation time t1 and the rotor acceleration k is G1=△G+G0, where △G is the speed change, △G=kt1; G0 is the initial speed, and the initial speed is 0, that is, G1=kt1, t1=G1 / k; The value of the acceleration k is a constant; The value of acceleration k can be calculated according to formula 1; Formula 1: , k is acceleration, t1 is the time required for the speed to reach the set speed G1, dt is a small increment of time t, and P is the total number of revolutions of the rotor; Therefore, by inputting the set speed G1 and acceleration k into the control system, the speed of the variable frequency brake motor can be controlled to reach the set speed G1 when the real-time number of turns of the variable frequency brake motor reaches 20% of the total number of turns; The uniform speed stage is the first 20%-80% of the number of rotations P. During the uniform speed stage, the speed G1 of the variable frequency brake motor remains unchanged. The duration of the uniform speed stage is t2, where t2=60%P / G1, p is the total number of rotations, and G1 is the set speed; The deceleration stage is the number of rotations P80%-100%. In the deceleration stage, the speed of the variable frequency brake motor is uniformly reduced to the threshold value A; The calculation formula for uniform speed reduction is G= G1-k (t-t1-t2), where t is the time for the rotor to rotate, t1 is the time required for the speed G to reach the set speed G1, t2 is the duration of the uniform speed stage, t-t1-t2 is the duration of the deceleration stage, G is the speed, G1 is the set speed, and k is the acceleration; The threshold value A is the rotation speed at which the rotor can be immediately stopped by the braking device.

3. The precise positioning method based on variable frequency brake motor according to claim 1, characterized in that: The specific contents of the positioning algorithm are as follows: Establish perpendicular constraints from point to plane; The equation of a plane is ax + by + cz + d = 0; The coefficients a, b, and c form an array, representing the normal vector of the plane; Convert the target position point into an array (X1, Y1, Z1) to represent the point vector; The plane plane is perpendicular to the straight line where the target position and the initial position are located; Calculate the dot product of the point vector and the normal vector plus the constant term d in the plane equation. Dot product N=X1a+Y1b+Z1c+d. If the absolute value of dot product N is less than the threshold value B, it means that the target position is perpendicular to the plane, and dot product N returns the F(x, y, z) constraint equation group. If the absolute value of dot product N is greater than the threshold value B, it means that the target position is not perpendicular to the plane, and dot product N does not return the F(x, y, z) constraint equation group. The threshold value B is a value close to 0; To create a distance constraint: The operating system measures a distance Q between the target position and the initial position according to the position sensor; Determine whether the distance Q between the target position and the initial position is equal to the distance S. If Q=S, return the F(x, y, z) constraint equation group. If Q≠S, do not return the F(x, y, z) constraint equation group. Combine these two constraints into a constraint equation set F(x, y, z) and return; The F(x, y, z) constraint equations are ； Establish the Jacobian matrix J of the constraint equations; The elements of the Jacobian matrix J are approximated by making a small perturbation to each variable x, y, and z, increasing dx, dy, and dz respectively, and then calculating the ratio of the change in the function value to the perturbation value; The Jacobian matrix J is ； The dx, dy, and dz are respectively small changes of x, y, and z, and dx, dy, and dz are 0.00001; The Newton-Raphson method is used to iteratively derive the position of the predetermined point based on the current point position and the advancing direction; The position of the predetermined point is the position point where the robot arm finally stops, which is deduced by the operating system based on the current position and forward direction of the robot arm; Set the initial point to (0,0,0), and according to the position of the robot arm (x, y, z), substitute the value of (x, y, z) into the F (x, y, z) constraint equation group and Jacobian matrix J; Set the maximum number of iterations MAX, and bring the values ​​of the F(x, y, z) constraint equation group and the Jacobian matrix J obtained above into the iterative formula, which is: thing (x, y, z) n+1 =vec(x,y,z) n – J*(-1)【vec(x,y,z) n 】 * thing (F) [thing (x, y, z) n 】; vec(x, y, z) n Represents the vector value of the vector (x, y, z) at the nth step, vec(x, y, z) n+1 Represents the vector value of the vector (x, y, z) at step n+1, vec(F) [vec(x, y, z) n 】 represents the value of the vector value of the nth step of the vector (x, y, z) in the equation F (x, y, z), J* (-1) [vec (x, y, z) n 】 represents the Jacobian matrix J【vec(x,y,z) n 】is the inverse matrix of The obtained vec(x, y, z) n+1 is compared with the threshold B. If vec(x, y, z) n+1 < B, the coordinate point corresponding to the obtained vec(x, y, z) n+1 is a predetermined point; if vec(x, y, z) n+1 > B, no predetermined point can be obtained, and the operating system reports an error.

4. The precise positioning method based on variable frequency brake motor according to claim 1, characterized in that: The specific contents of step S4 are as follows: S41: The robot arm rotates itself to an angle a; The mechanical arm comprises a rotary joint, and the mechanical arm realizes rotation by adjusting the rotary joint; The a is the angle between the initial position and the target position; S42: The robot arm starts to move from the initial position to the target position along the angle a; When the robot arm is moving, the position sensor collects the position points (X, Y, Z) of the robot arm in real time. According to the positioning algorithm, the control system continuously calculates the coordinates of the predetermined point. When the coordinates of the predetermined point are inconsistent with the coordinates of the target position point, the control system reports an error and the robot arm stops moving; if the coordinates of the predetermined point are consistent with the coordinates of the target position point, the robot arm continues to move.

5. The precise positioning method based on variable frequency brake motor according to claim 1, characterized in that: The specific content of step S5 is: S51: The robot arm reaches the target position and grabs the goods according to the power output corresponding to the weight of the goods; A weighing device is provided at the end of the mechanical arm, which can accurately weigh the mass of the grabbed goods; When the robot arm contacts the cargo, it determines the mass m of the cargo, and the variable frequency brake motor outputs the corresponding power L according to the mass of the cargo; The power L can ensure that the robotic arm can firmly grasp the goods.

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