Method for interpolating a read signal from an incremental encoder

Abstract

Method for interpolating a read signal of an incremental encoder that detects a rotation angle by means of two pseudo-sine wave signals having different phases, which are obtained from an incremental encoder having a slotted disk connected to a rotary axis of a vertically rotating motor of a three-dimensional scanner and a fixed scanning disk, the procedure includes: Pulsing one of the pseudo-sine wave signals as an angle signal; Counting the pulsed angle signal; Storing counter values ​​of a clock signal, which are counted separately in relation to a time of each rise of the angle signals, and in relation to a time of each rise of signals for the command of detection of a rotation angle, which are output by a control section of the three-dimensional scanner; and Calculating a rotation angle “θ” at the time of the signal rise to the instruction for the detection of the rotation angle, using the operational equation θ = {i + (Ttrig i - Ti) / (Ti+1 - Ti)} × λ, in which the following are used: a count value Ttrig i of the clock signal, which is stored at the time of the signal rise to command the detection of the rotation angle, a count value “i” of the pulsed angle signal, which is counted immediately before the signal rises to command the detection of the rotation angle, The respective count values ​​Ti and Ti+1 of the clock signal, which are stored at the time of the rise of the respective angle signals, which rise before and after the rise of the signal for the instruction to detect the rotation angle, and a division angle “λ”, which is an angle of division of a slot among several slots acting as a principal scale and arranged at regular intervals along a circular circumference of the slot disk.

Description

Technical field

[0001] The present invention relates to a method for interpolating a read signal of an incremental encoder and in particular a method for interpolating a read signal of an incremental encoder which is expediently used for detecting a rotation angle of a vertical rotation of a three-dimensional scanner, i.e. a rotation in which a horizontal axis is used as the axis of rotation. Relevant state of the art

[0002] In a conventional incremental encoder, two signals resembling sine waves (pseudo-sine wave signals) with phases differing by 90° are generally generated in the detection section. Interpolation methods, which achieve higher resolution by using these two signals, are divided into analog and digital systems. The analog system includes an analog subdivision system in which the two signals with the different phases are synthesized in an electrical circuit, while their proportions are varied to generate signals with different phase differences, thus yielding signals with fine divisions.However, this analog subdivision system has several disadvantages: the increased resolution necessitates a more complex electrical circuit, a larger mounting area is required due to the larger scale of the circuit, and the overall cost is higher. When the incremental encoder is used to detect the rotation angle of a 3D scanner's vertical rotation, the scanner's vertical rotation speed can reach several thousand revolutions per minute. Furthermore, the larger mounting area does not allow for secure attachment. At this high rotational speed, the frequency characteristics of an amplifier tend to alter or degrade the analog characteristics, rendering the analog subdivision system unsuitable.

[0003] The digital system, on the other hand, is suitable for detecting the rotation angle of the vertical rotation of a three-dimensional scanner, since the circuit scale of the digital system can be implemented smaller than that of the analog subdivision system. The digital system includes a digital interpolation system in which the two signals with different phases are digitally transformed to obtain the digitally transformed signals S1 and S2, and the rotation angle θ is calculated using θ = tan . -1The S2 / S1 angle is calculated using an arctangent based on the S2 / S1 signals to obtain the angle with fine subdivisions, resulting in higher resolution. The interpolation method is created by improving the digital interpolation method, significantly enhancing resolution by calculating the position of a measured point within an interpolation range subdivided by the zero points of multiple signals. For this purpose, a proportional operating system based on two signals selected within the aforementioned interpolation range is used (Patent Publication 1). Publications on the state of the art

[0004] Patent Publication 1: JP-B-5-24445 Overview of the invention Problems to be solved by the invention

[0005] The conventional analog subdivision system, including the improved analog subdivision system described above, has the disadvantage that, since the proportional operation is based on the voltage values ​​of the analog signals to be digitally transformed with the two different phases, the system is susceptible to influences such as wave distortion of the two signals and the precision of the phase difference. Accordingly, the improved analog subdivision system cannot meet the precision and stability requirements for vertical rotation, where the horizontal axis of the three-dimensional scanner rotates at speeds of up to several thousand revolutions per minute.

[0006] The present invention was designed to eliminate these disadvantages, and it is an object of the invention to create a method for interpolating a read signal of an incremental encoder which maintains higher precision and stability even during high-speed rotation of a horizontal axis of rotation of a three-dimensional scanner in the range of several thousand revolutions per minute. Means to solve the problems

[0007] The present invention (claim 1) for solving the problem is provided as a method for interpolating a read signal of an incremental encoder that detects an angle of rotation by means of two pseudo-sine wave signals having different phases, which are obtained from an incremental encoder comprising a slotted disk connected to a rotary axis of a vertically rotating motor of a three-dimensional scanner and a fixed scanning disk, wherein the method comprises: pulsing one of the pseudo-sine wave signals as an angle signal, counting the pulsed angle signal, storing count values ​​of a clock signal which are counted separately with respect to a time of each rise of the angle signals, and with respect to a time of each rise of signals for the instruction to detect an angle of rotation, which are output by a control section of the three-dimensional scanner.and calculating a rotation angle “θ” at the time of the signal rise to command the detection of the rotation angle, using the operational equation θ = {i + (Ttrig i - Ti) / (Ti+1 - Ti)} × λ, in which the following are used: a count value Ttrig i of the clock signal, which is stored at the time of the signal rise to command the detection of the rotation angle, a count value “i” of the pulsed angle signal, which is counted immediately before the signal rises to command the detection of the rotation angle, respective count values ​​Ti and Ti+1 of the clock signal, which are stored at the time of the rise of the respective angle signals, which rise before and after the signal rises to command the detection of the rotation angle, and a division angle “λ”, which is an angle of division of several slots that act as a main scale and are arranged at regular intervals along a circular circumference of the slotted disk.

[0008] The method for interpolating a read signal of an incremental encoder, which is also provided for solving the problem according to claim 2, is characterized in that the signal for commanding the detection of the rotation angle is a trigger signal that is output by the control section of the three-dimensional scanner during a scanning operation.

[0009] In this way, the rotation angle is calculated based on the time interval between the respective signal rises. This calculation uses the count values ​​incremented at the rise of the angle signal (generated by pulsing one of the pseudo-sine wave signals) and at the rise of the signal triggering the detection of the rotation angle, output by the control section of the three-dimensional scanner (e.g., a trigger signal issued at the time of rotation angle detection). Accordingly, the wave distortion of the pseudo-sine wave signals acting as the angle signal, and the precision of the phase difference between the other pseudo-sine wave signal and the signal itself, are unlikely to have any significant influence, even at higher rotational speeds in the range of several thousand revolutions per minute. Effect achieved with the invention

[0010] The method for interpolating a read signal from an incremental encoder according to claim 1 achieves the effect that the rotation angle of the vertical rotation of a three-dimensional scanner can be detected with high precision and stability, even during its rotation at a high speed of several thousand revolutions per minute. Furthermore, the method according to claim 2 achieves, in addition to the effect described above, the reliable coordination of the scanning operation of the three-dimensional scanner and the operation of detecting the rotation angle, since the trigger signal output during the scanning operation is used as the signal to command the detection of the rotation angle. Brief description of the characters Fig. Figure 1 shows a block diagram of a three-dimensional scanner according to an embodiment of the present invention; Fig. Figure 2 shows a block diagram of an incremental encoder which, according to the foregoing embodiment, reads a vertical rotation angle; and Fig. Figure 3 shows a timing diagram to illustrate a process of processing a read signal according to the above embodiment. Embodiments for implementing the invention

[0011] An exemplary embodiment of the present invention will be explained in more detail below in connection with the accompanying drawings. According to Fig. Figure 1 comprises a three-dimensional scanner 1 with a motor 3 for vertically rotating a scanning section (not shown), which contains a laser aperture and configuration part for a distance sensor 2, and a motor 4 for horizontally rotating the scanning section. A slotted disk 11 of a vertical angle encoder 10 is arranged on the axis of rotation of the vertically rotating motor 3, while a slotted disk (not shown) of a horizontal angle encoder 30 is arranged on the axis of rotation of the horizontally rotating motor 4. The distance sensor 2 is configured to perform the scanning operation by emitting a distance-measuring laser beam in the form of a pulsed wave from the aforementioned (not shown) laser aperture and receiving its reflected wave, the scanning range of the distance sensor being arbitrarily set.

[0012] The three-dimensional scanner 1 automatically captures the entire scanning area during the scanning operation and saves it as image data in an image file. It includes a camera section 5, which displays the image data on a monitor as needed; a communication section 6, which sends and receives various signals and data between itself and an external device (not shown); and a user interface (UI) section 7 with a monitor, a touchscreen keypad, and an operating button. All operations of the three-dimensional scanner 1, including the scanning operation, are controlled by a control section 8. The scanning operation is performed in response to a trigger signal that commands the emission of the distance-measuring laser beam. In the present embodiment, the trigger signal is used as the signal to command the detection of the rotation angle.

[0013] According to Fig. In the vertical angle encoder 10, a scanning disk 12 is fixed relative to the slotted disk 11, which rotates with the axis of rotation of the vertically rotating motor 3, such that it points towards the aforementioned slotted disk 11. The irradiation light emitted by a lamp 13 passes through slots formed in the slotted disk 11 and the scanning disk 12 and reaches a light receiving element 14, thereby outputting A and B phase signals, which are two pseudo-sine wave signals with phases differing by 90°, and a pulsed Z phase signal, which is an original signal that is output with each rotation of the slotted disk 11 (see Fig. 3).

[0014] In the present embodiment, the A-phase signal of the two types of pseudo-sine wave signals is used as the angle signal, while the B-phase signal is used to detect the direction of rotation. The irradiation light from the lamp 13 is controlled in on / off mode by means of a control signal from a control circuit 15, which receives a control signal from the control section 8, and all operations of the vertical angle encoder 10 are controlled by the control section 8. The configuration of the horizontal angle encoder 30 is known, and its operation does not differ from that of a conventional incremental encoder. Furthermore, the interpolation method according to the present invention is not applied to the encoder 30, so it will not be described in detail here.

[0015] The following will be discussed in connection with Fig. 2. The design of the interpolation operation is described. The pseudo-sine wave signals of the A and B phases are input into a comparator circuit 16, the comparator circuit 16 being configured to output the respective signals in the form of square waves (see Fig. 3) Since the B-phase signal is not directly involved in the interpolation method according to the present invention, it will not be described in connection with the following operations. The A- and Z-phase signals, pulsed as square waves and output by the comparator circuit 16, are counted as input signals in a counting circuit 17, and the count values ​​are configured to be input by the counting circuit 17 into the control section 8. The count value of the pulsed A-phase signal is configured to be reset to zero when the Z-phase signal, which is the original signal, is input into the counting circuit 17. The A-phase signal output by the comparator circuit 16 is configured to also be input into a latching circuit 18.

[0016] The interpolation method is described below in connection with the Fig. 2 and Fig.As described in section 3, among the A- and B-phase signals and the Z-phase signal detected in the vertical angle encoder 10, the A-phase signal, which is the pseudo-sine wave signal, and the Z-phase signal, which is the pulsed signal, are pulsed into square waves in the comparator circuit 16, and the subsequent operations are performed using the A-phase signal as the angle signal. The A-phase square wave signal, which is the pulsed angle signal, is counted in the counter circuit 17, and the count values ​​i, i+1, ... are input into the control section 8. The count values ​​of the A-phase square wave signal are reset to zero when the Z-phase signal, which is the original signal, is input into the counter circuit 17.

[0017] Furthermore, a clock signal generated in an oscillator circuit 19 is counted in a counter circuit 20, and for each rise of the A-phase square wave signal, the count values ​​Ti, Ti+1, ... are stored in the latch circuit 18. When, during the scanning operation, the trigger signal is output by the distance sensor 2 from the control section 8 of the three-dimensional scanner 1, and the signal is for the instruction to detect the rotation angle, the count values ​​Ttrig i, Ttrig i+1 ... of the clock signal are stored in the aforementioned latch circuit 18 for each rise of the trigger signal. These stored count values ​​are then input from the latch circuit 18 into the control section 8.

[0018] If the count value of the A-phase square wave signal (1) input into control section 8 is defined as "i", then the count value of the clock signal input into control section 8, stored at the time of the rise of the A-phase square wave signal, is similarly defined as "Ti", and the count value of the clock signal input into control section 8, stored at the time of the rise of the A-phase square wave signal (1), is similarly defined as "Ttrig i", and furthermore, the count value of the clock signal input into control section 8, stored at the time of the rise of the A-phase square wave signal (2), is similarly defined as "Ti+1", and a division angle, which is an angle of division of several slots acting as a main scale and at regular intervals along the are arranged around the circumference of the slotted disk 11,and which has already been entered into control section 8, is defined as “λ”, and a rotation angle from the rise of the A-phase square wave signal (1) to the rise of the trigger signal (1) at the input of the trigger signal (1) is expressed as {(Ttrig i - Ti) / (Ti+1 - Ti)} ×λ. Thus, a rotation angle θ of a cycle from a starting point to a detection point where the interpolation is performed, in this case expressed by an operational equation θ = {i + (Ttrig i - Ti) / (Ti+1 - Ti)} ×λ.

[0019] “λ” is the angle of a division of the main scale of the slotted disk 11 and, after it has been calculated, can be entered into control section 8. Control section 8 calculates the rotation angle “θ” using the respective count values ​​“i”, Ttrig 1, Ti and Ti+1 and the aforementioned “λ”, which was pre-entered according to the above operational equation, for each output of the trigger signal.

[0020] When calculating the rotation angle “θ” from the output of the trigger signal (2), an operational equation θ = {i + (Ttrig i+1 - Ti) / (Ti+1 - Ti)} ×λ is used. In this way, the rotation angle “θ” can be calculated for each time at which the trigger signal is input into the latch circuit 18, which, according to the present embodiment, is the signal for commanding the detection of the rotation angle.

[0021] The present invention is not limited to the embodiments listed above. For example, instead of the trigger signal output from the control section 8 during the scanning operation, a different output signal can be used as the signal to command the detection of the rotation angle. The slotted disk 11 can be arranged not only directly on the axis of rotation of the vertically rotating motor 3, but also indirectly in such a way that the slotted disk 11 always rotates at the same speed as the axis of rotation. Reference symbol list 1 three-dimensional scanner 2 distance meters 3 vertically rotating motors 8 Control section 10 vertical angle encoders 11 slotted disc 12 scanning disc 13 Lamp 14 Light receiving element 15 Control circuit 16 Comparator circuit 17.20 Counting circuit 18 Latch Circuit 19 Oscillator circuit

Claims

[1] Method for interpolating a read signal of an incremental encoder which detects a rotation angle by means of two pseudo-sine wave signals having different phases, which are obtained from an incremental encoder which has a slotted disk connected to a rotary axis of a vertically rotating motor of a three-dimensional scanner and a fixed scanning disk, the procedure includes: Pulsing one of the pseudo-sine wave signals as an angle signal; Counting the pulsed angle signal; Storing counter values ​​of a clock signal, which are counted separately in relation to a time of each rise of the angle signals, and in relation to a time of each rise of signals for the command of detection of a rotation angle, which are output by a control section of the three-dimensional scanner; and Calculating a rotation angle “θ” at the time of the signal rise to the instruction for the detection of the rotation angle, using the operational equation θ = {i + (Ttrig i - Ti) / (Ti+1 - Ti)} × λ, in which the following are used: a count value Ttrig i of the clock signal, which is stored at the time of the signal rise to command the detection of the rotation angle, a count value “i” of the pulsed angle signal, which is counted immediately before the signal rises to command the detection of the rotation angle, The respective count values ​​Ti and Ti+1 of the clock signal, which are stored at the time of the rise of the respective angle signals, which rise before and after the rise of the signal for the instruction to detect the rotation angle, and a division angle “λ”, which is an angle of division of a slot among several slots acting as a principal scale and arranged at regular intervals along a circular circumference of the slot disk. [2] Method for interpolating a read signal from an incremental encoder according to claim 1, characterized by , that the signal for the command to detect the rotation angle is a trigger signal that is output by the control section of the three-dimensional scanner during a scanning operation.

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