KR101144502B1 - Method for scheduling Time Triggered Controller Area Network - Google Patents

Abstract

 The present invention discloses a TTCAN scheduling method. The present invention relates to a Time-Triggered Controller Area Network (TTCAN) scheduling method, comprising: classifying a periodic message into one or more lower message sets using a predetermined algorithm, each of the lower message sets including a plurality of messages having similar transmission times. And mapping a message included in each sub-message set to the same transmission string. According to the present invention, it is possible to minimize the maximum interval of the exclusive window to prevent the transmission delay of the aperiodic message.

Description

Method for scheduling Time Triggered Controller Area Network

The present invention relates to a TTCAN scheduling method, and more particularly, to a method of preventing transmission delay of an aperiodic message by minimizing an exclusive window section to which a periodic message is allocated.

TTCAN (Time Triggered Controller Area Network) is a method in which a plurality of nodes are connected and communicated on a serial bus, which ensures periodic delivery of messages by having a time master schedule messages on the bus. do.

Since TTCAN transmits a message according to a predetermined schedule, TTCAN can provide higher predictability and deterministic behavior than a controller area network (CAN).

Because of these features, TTCAN is widely used in a variety of applications that require real-time, such as automotive networks, medical equipment, industrial, automotive systems.

In order to apply TTCAN to a real-time communication system, creating a message schedule called a system matrix becomes an important issue.

Existing studies deal with this TTCAN scheduling from two perspectives. The first point is to find a system matrix that can satisfy both the period and deadline of a given message.

This problem is presumed to be non-deterministic polynomial-time hard (NP-hard), but it is known that it is possible to find an effective schedule by applying a traditional real-time scheduling algorithm such as rate monotonic scheduling (RMS) or last slack time (LST).

The second aspect is to optimize the system matrix that has already been created for a particular purpose. Optimization targets include minimizing jitter, minimizing the number of time triggers, minimizing bandwidth usage, and many studies have been conducted.

In general, the basic cycle defined by the TTCAN may include an exclusive window in which periodic messages are arranged and an arbitration window in which acyclic messages are arranged. In general, real-time applications include aperiodic messages as well as periodic messages, and TTCAN is designed to support both types of messages.

However, the conventional scheduling method mainly concentrates on the performance of periodic messages and overlooks the performance of aperiodic messages. Therefore, the worst-case transmission delay of aperiodic messages occurs when the maximum period of the exclusive window becomes very large in a given basic cycle. There is a problem.

In the present invention, to solve the problems of the prior art as described above, we propose a TTCAN scheduling method that can minimize the transmission delay of aperiodic messages.

According to a preferred embodiment of the present invention to achieve the above object, as a time-triggered controller area network (TTCAN) scheduling method, the number of time slots required in the periodic messages is less than the number of basic cycles (Basic cycle) Classifying the classified messages into one or more lower message sets using a preset algorithm; And mapping a message included in each lower message set to the same transmission column.

According to another aspect of the present invention, there is provided a time-triggered controller area network (TCCAN) scheduling method, comprising: generating a first system matrix for all periodic messages using ratio monotonic scheduling; Searching for a partial use transmission column in the first system matrix; And relocating a plurality of messages included in the searched transmission column according to a preset algorithm to generate a second system matrix having a minimum maximum window of an exclusive window.

According to another aspect of the present invention, a time-triggered controller area network (TCCAN) scheduling method, comprising: classifying a periodic message into one or more sub message sets using a predetermined algorithm, each of which has a similar transmission time Includes a plurality of messages; And mapping a message included in each lower message set to the same transmission column.

According to the present invention, since the periodic messages are rearranged to minimize the maximum period of the exclusive window in the basic cycle, there is an advantage of preventing the transmission delay of the aperiodic message.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals are used for like elements in describing each drawing.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate a thorough understanding of the present invention, the same reference numerals are used for the same means regardless of the number of the drawings.

The present invention provides a schedule that the scheduler of the TTCAN can improve the transmission efficiency of the aperiodic message while ensuring the real-time of the periodic message.

Prior to describing the method according to the invention, a brief review of the basic cycle structure in a TTCAN system is given.

1 is a view showing the basic structure of the TTCAN basic cycle to which the present invention is applied.

As illustrated in FIG. 1, the basic cycle may include a reference message, an exclusive window, an arbitration window, and a free window.

The reference message indicates the start of the basic cycle and controls the timing of the basic cycle.

An exclusive window is a piece of time with a length that can accommodate the message and data to be sent. In such an exclusive window, periodic messages are placed.

The arbitration window is an area in which an aperiodic message is placed. In the arbitration window, many nodes attempt to transmit the message aperiodically. Many nodes that want bus access in an arbitration window generally compete by non-destructive bitwise arbitration methods.

Free windows are a preliminary area for future expansion of the TTCAN system.

As noted above, in the TTCAN basic cycle, periodic messages are placed in an exclusive window, and aperiodic messages are placed in an arbitration window following the exclusive window.

Here, TTCAN scheduling is a process of properly placing periodic messages.

, 전송 시간을

로 표기할 수 있으며,TTCAN에서 이러한 메시지 집합을 스케줄링 하기 위해서는, 모든 주기적 메시지들을 시스템 행렬 S 에 적절하게 매핑해야 한다. When the periodic message set M = {M1, M2, ...} , the period of the message M _i (M _i ∈ M)

, Transfer time

In order to schedule such a message set in TTCAN, all periodic messages must be properly mapped to the system matrix S.

개의 베이직 사이클(basic cycle)과

개의 전송 열(transmission column)로 구성된다. Where the system matrix S is

Basic cycles

It consists of four transmission columns.

을 시스템 행렬

에 매핑하기 위해서는 반드시 TTCAN 표준문서에 규정된 제약사항을 고려해야 한다. 첫째, 베이직 사이클의 개수는 2의 지수 승이다. 둘째, 시스템 행렬 내의 모든 베이직 사이클의 크기(

)는 동일하다. 셋째, 동일한 전송 열 내의 모든 타임 슬롯 (time slot)의 크기는 같다. 또한, 구현된 하드웨어에 따라 타임 트리거(time trigger) 개수에 제한이 있다.Set of messages

System matrix

In order to map the data, the constraints specified in the TTCAN standard document must be taken into account. First, the number of basic cycles is an exponential power of two. Second, the magnitude of every basic cycle in the system matrix (

) Is the same. Third, all time slots in the same transmission string have the same size. In addition, there is a limit on the number of time triggers according to the implemented hardware.

The present invention generates a system matrix S ' (second system matrix) in which the exclusive window maximum interval is minimized by rearranging the periodic messages in the schedulable system matrix S (first system matrix) based on the above constraints.

In the present invention, an algorithm for relocating a periodic message to minimize the maximum window interval is defined as a Transmission Time Cohesive Partitioning (TTCP) algorithm.

Here, the first system matrix refers to a system matrix according to a conventional scheduling method such as a system matrix based on an existing RMS, and the second system matrix refers to a system matrix generated by applying a scheduling method according to the present invention.

In the following description, it is assumed that the first system matrix is a system matrix based on RMS.

Rate-Monotonic Scheduling (RMS) refers to a method of giving high priority to nodes in order of shortest execution period.

Figure 2 schematically shows a first system matrix and a second system matrix according to the present invention, assuming that each system matrix is composed of two basic cycles.

, 제2 베이직 사이클에서의 배타 윈도우 길이가

이다. 본 발명은 제1 시스템 행렬에서, 주기적 메시지들을 미리 설정된 알고리즘에 따라 재배치하여 도 2b와 같은 제2 시스템 행렬을 생성한다.As shown in FIG. 2A, the length of the exclusive window in the first basic cycle in the first system matrix is

, The exclusive window length in the second basic cycle

to be. In the first system matrix, periodic messages are rearranged according to a predetermined algorithm to generate a second system matrix as shown in FIG. 2B.

, 제2 베이직 사이클에서의 배타 윈도우 길이가

이다. As shown in FIG. 2B, in the second system matrix, the length of the exclusive window in the first basic cycle is

, The exclusive window length in the second basic cycle

to be.

Here, the maximum interval of the exclusive window in the first system matrix is T ₁ , and the maximum interval of the exclusive window in the second system matrix is T ₁ ′ .

The present invention properly rearranges the periodic messages in one basic cycle so that the maximum interval of the exclusive window does not become too large as compared to the other in one basic cycle.

Such relocation is to prevent the worst-case scheduling delay of the aperiodic message while ensuring the real time of the periodic message.

In the case that requires the use of certain non-periodic message bus in the first system matrix, one must wait for a time of as long as up to T _1, the second, according to the system matrix aperiodic messages waiting for as little up to T ₁ 'than T ₁ Since only time is required, the present invention can prevent the worst transmission delay of aperiodic messages.

Hereinafter, a scheduling method according to the present invention will be described in detail with reference to FIG. 3.

3 is a diagram schematically illustrating a process of scheduling TTCAN by a scheduler according to an exemplary embodiment of the present invention.

Referring to FIG. 3, a first system matrix is generated according to RMS (step 300).

In the first system matrix, a shorter period of time message is placed in the forward transmission column.

Thereafter, the scheduler classifies the message to which the algorithm according to the present invention (hereinafter, referred to as 'tTCP algorithm') is applied (step 302).

Step 302, if the first system matrix includes a fully utilized transport column and a non-fully utilized transport column, searches for a periodic message included in the partially used transport column and replaces the algorithm according to the present invention. Decide on the message to apply.

Here, the total used transmission column refers to a transmission column without an empty time slot in the exclusive window of the first system matrix, and the partial use transmission column refers to a transmission column in which an empty time slot exists.

If it consists of N _R basic cycles in the first system matrix by RMS, the transmission column containing the message transmitted repeatedly in all the basic cycles becomes the total used transmission column, and the message not transmitted repeatedly in all the basic cycles. The transmission string containing is a partial use transmission string.

Step 302 is a process of searching for a message included in the partial use transmission column. The message to which the TTCP algorithm is to be applied may be determined by comparing the number of time slots of each periodic message and the number of basic cycles N _R.

In other words, if the number of time slots is equal to the number of basic cycles, then the corresponding periodic message must be included in all basic cycles, so that is the message included in the total usage transport column. This is the message that is included.

As described above, the scheduler searches for a message in which the number of time slots is smaller than the number of basic cycles.

According to the present invention, the number of time slots is determined as follows according to the period of the message and the size and number of basic cycles.

는 M _i 에 요구되는 타임 슬롯 개수,

은 베이직 사이클의 크기,

은 베이직 사이클의 개수,

는

의 주기here,

Is the number of time slots required for M _i ,

Is the size of the basic cycle,

Is the number of basic cycles,

Is

Cycle of

For example, when a period of a predetermined message is 40000, the number of basic cycles is 8, and the size of the basic cycles is 10000, the number of time slots of the corresponding message may be calculated as 2.

As described above, since the number of time slots of a periodic message is determined by the period of the corresponding message, the comparison of the number of time slots and the number of basic cycles is the same as comparing the period of each periodic message and the size of the basic cycle ( W _R ). It may be a concept.

Thereafter, the scheduler applies the TTCP algorithm to the periodic messages included in the partial use transmission column of the first system matrix to classify the plurality of periodic messages into one or more lower message sets (step 304).

According to a preferred embodiment of the present invention, step 304 classifies the lower message set using information such as the number of basic cycles, the transmission time of each periodic message included in the partial use transmission column, and the number of time slots.

Preferably, in step 304, one or more messages having similar transmission times according to the transmission time of each periodic message belong to the same lower message set.

As mentioned above, the third of the TTCAN scheduling constraints is that "the size of all time slots in the same transmission column is the same." That is, the size of the transmission column is determined to be the largest transmission time among the messages scheduled in the same transmission column. Under these constraints, it may be an effective way to group the messages in the partial use transport sequence into messages with similar size transfer times and rearrange them within the same transport sequence.

의 전송 시간이 각각 10, 30, 20, 40 일 때, 메시지들을

으로 분류하고, 각각 두 개의 전송 열에 배치하면, 즉

,

를 제1 전송 열에,

,

를 제2 전송 열에 배치하면, 세 번째 제약사항에 따라 전체 전송 시간은 70 (=30 + 40 = 제1 전송 열 전송 시간 + 제2 전송 열 전송 시간)으로 결정된다. 반면 메시지 집합을 전송 시간이 유 사한

로 분류하면 전체의 전송 시간은 60 (=20 + 40) 이 되어 이전의 분류보다 효율적인 전송 열을 얻을 수 있다.For example, a periodic set of messages included in the partial use transport column.

When the transmission times of 10, 30, 20, and 40 are respectively,

Classified into two columns of transfer, i.e.

,

In the first transfer column,

,

If is placed in the second transmission column, the total transmission time is determined to be 70 (= 30 + 40 = first transmission column transmission time + second transmission column transmission time) according to the third constraint. In contrast, message sets have similar transfer times.

In this case, the total transmission time is 60 (= 20 + 40), which is more efficient than the previous classification.

According to the present invention, each sub message set corresponds to a predetermined transmission column, and if the first to fourth transmission strings are all used transmission columns, the first sub message set is a fifth transmission column and the second sub message set is It may correspond to the sixth transmission string.

In addition, in step 304, a message arrangement is determined to minimize the maximum interval of the exclusive window in each basic cycle. Preferably, in step 304, the sum of the number of time slots of periodic messages included in each sub-message set is the number of basic cycles. Categorize the lower message set as

This is to place a message while minimizing an empty slot in a given transmission column.

When the classification of the lower message set is completed in step 304, the scheduler rearranges each periodic message based on the one or more lower message sets to generate a second system matrix (step 306).

The TTCP algorithm according to the present invention is as follows. Hereinafter, the TTCP algorithm and the process performed in step 304 will be described in more detail with reference to FIG. 4.

Here, Ψ is the entire set of periodic messages placed in the partial use transport column, and TTCP classifies the messages in Ψ, that is, the entire periodic messages arranged in the partial use transport column into individual sub-message sets ({ Ψ ₁ , Ψ ₂ , , .., Ψ _m } ∈Ψ). R ( x ) denotes the number of time slots a message x or message set x needs within the size N _R W _R of the entire system matrix. Therefore, with respect to the Ψ (M _i ∈ Ψ) containing M _i, R (M _i) can be obtained through the following formula: _{R (M i) = N R} W R / P i.

F ( x ) represents the number of empty time slots in which a message can be placed in the partial use transport column.

4 is a flowchart illustrating a detailed process of classifying a lower message set according to the present invention, and FIG. 4 illustrates a process of determining a periodic message belonging to one lower message set.

Referring to FIG. 4, in step 302, a message found to be included in the partial use transmission column is sorted in descending order according to the transmission time (step 400).

Thereafter, a first lower message set Ψ ₁ is generated (step 402), and together with the setting value F ( Ψ ₁ ) = N _R for determining a message included in the first lower message set (step 402). Step 404).

Then, the number of time slots of the first periodic message having the largest transmission time by sorting in descending order is compared with the set value F ( Ψ ₁ ) in step 404 (step 406).

If R ( x ) is less than or equal to the set value, it is determined that the periodic message is included in the first lower message set (step 408).

On the other hand, when it is determined that the first periodic message is included in the first lower message set, the set value F ( Ψ ₁ ) of step 404 is updated to N _R -R ( M ₁ ) (step 410).

Step 410 is a process of updating the setting value by subtracting the number of time slots of the first periodic message from the initial setting value. Herein, the updated setting value means the number of remaining slots for the first lower set of messages.

Thereafter, it is determined whether the updated set value is 0 in step 410 (step 412), and if the updated set value is not 0, the second periodicity in which the transmission time is equal to the first periodic message or corresponds to the next sequence is determined. Step 406 proceeds with respect to the message.

When the number of time slots of the second periodic message is less than or equal to the updated setting value, steps 408 to 410 are repeatedly performed.

On the other hand, if the number of time slots of the second periodic message is larger than the updated setting value, the flow proceeds to step 410.

Here, if the updated set value is not 0, step 406 is performed on the third periodic message whose transmission time is equal to or less than the second periodic message, but if the updated set value is 0, the second lower message set Processes 402 to 412 are performed sequentially (step 414).

The TTCP algorithm according to the present invention sorts the messages arranged in the partial use transmission column in descending order according to the transmission time, and then forms a lower message set to be placed in the transmission column through two loops. Since the maximum number of iterations for each of the two loops is n , the algorithm according to the invention has a complexity of O ( n ² ).

On the other hand, according to the present invention, it may also occur if the transmission time of any message in the Ψ _i is smaller than the transmission time of the message in the Ψ _{i + 1.} The reason is that the algorithm according to the invention tries to place the messages in Ψ into the empty slot as far forward as possible.

The scheduler according to the present invention rearranges the messages in the lower message set in each transmission string after the messages in P have been classified into the lower message sets. Three heat transfer size according to the second constraint is that the message {T _j being placed in the same heat transfer: M _i ∈ Ψ _i } the largest transmission time Is determined by ( T _max ( Ψ _i )).

Hereinafter, the results of the scheduling method according to the present invention will be described with reference to Table 1 and FIGS. 5 to 6.

Table 1 is a modified table of the well-known PSA message set as a benchmark.

The original PSA message set has a non-harmonic period, but for the sake of illustration, all periodic messages are modified so that the period has a multiple of the exponent of two of the smallest messages, producing a modified message set.

Here, N _R W _R has periodicity, and P _i and W _R are harmonic, so they are separated from each other. Therefore, N _R W _R is divided by P _i . In the present invention, for the convenience of description, it is assumed that the value of N _R W _R has a least common multiple of all message periods, whereby W _R is proportional to the period of the smallest message.

Applying the RMS to the message set shown in Table 1 can obtain a system matrix as shown in FIG.

In the system matrix of FIG. 5, the number of basic cycles is 8, and the size of the basic cycles is set to 10000.

In the system matrix according to RMS as shown in FIG. 5, the maximum section of the exclusive window may be set too long in a specific basic cycle.

That is, looking at the first basic cycle, the maximum interval of the exclusive window is 9112, and thus a maximum delay of 9112 may occur when an aperiodic message requires the use of a bus.

On the other hand, the case where the algorithm according to the present invention is applied will be described.

The messages placed in the partial use transport column of the entire message set M ₁ through M ₁₂ are M ₅ through M ₁₂ , which correspond to messages whose period is greater than the size of the basic cycle.

When these eight periodic messages are sorted in descending order according to the transmission time, they are sorted in the following order. In the following, the number in parentheses is the number of time slots in each message.

(1) transmission time 968 = { M ₁₁ (1)}

(2) Transmission time 808 = { M ₁₀ (2), M ₉ (2) , M ₈ (2) , M ₅ (4)}

(3) transmission time 736 = { M ₆ (4)}

(4) Transmission time 656 = { M ₇ (4)}

(5) Transmission time 504 = { M ₁₂ (1)}

The lower message set classification process is performed according to the descending sort as described above.

The initial setting value is set to 8, which is the number of basic cycles.

Is the time slot number (1) for the M _11, since the initial setting value is less than ₁₁ 8 M are determined to belong to the first sub-set of messages, the set value is updated by 8-1 = 7.

As such a method, it is determined that M ₁₀ to M ₈ belong to the first lower message set.

On the other hand, when the comparison process is performed on M ₅ corresponding to the next sequence, since there is already one empty remaining slot (updated set value) by the algorithm up to M ₈ , the number of time slots of M ₅ is 4 , M ₅ may not belong to the first sub-message set.

In this case, the scheduler searches for a message whose time slot number is the same as the number of remaining slots in the calculation process among the messages whose transmission time is next, and determines that the message belongs to the first lower message set.

In the above example, M ₁₂ having the number of time slots 1 may be included in the first lower message set.

When M ₁₂ is included in the first lower message set, the set value becomes 0, and accordingly, the next lower message set classification process is repeatedly performed.

The result of sub-message set classification determined through this execution result is as follows.

(1) first sub-message set ( Ψ ₁ ) = { M ₁₁ , M ₁₀ , M ₉ , M ₈ , M ₁₂ }

(2) second sub-message set ( Ψ ₂ ) = { M ₅ , M ₆ }

(3) third sub-message set ( Ψ ₃ ) = { M ₇ }

Here, the total number of time slots of the messages included in the first to second lower message sets is equal to the number of basic cycles. As such, the present invention is to rearrange the message with no empty slots for the transmission rows that are located after the total usage transmission columns.

When the periodic messages are rearranged according to the lower message set as described above, as shown in FIG. 6, a system matrix can be obtained in which the maximum interval of the exclusive window is minimized in the basic cycle.

T ₁₁

968, T _max (Ψ ₂ )

T ₅

808, T _max (Ψ ₃ )

T ₇

656, 총 합은 2512)을 합한 값인 5528이 되며, 이에 따라 비주기적 메시지는 종래에 비해, 약 3584만큼 시간 지연이 감소될 수 있어 비주기적 메시지의 전송 효율이 한층 개선된다. According to the system matrix according to the present invention, the maximum interval of the exclusive window of the basic cycle is the transfer time T _max ( Ψ ₁ ) of the transfer sequence rearranged to the transfer time 3016 of the total use transfer sequence.

T ₁₁

968, T _max ( Ψ ₂ )

T ₅

808, T _max ( Ψ ₃ )

T ₇

656, the total sum is 5528, which is the sum of 2512). Accordingly, the time delay of the aperiodic message can be reduced by about 3584, compared with the conventional method, thereby further improving the transmission efficiency of the aperiodic message.

In the above description, the second system matrix is newly generated under the premise of the system matrix based on RMS. However, the present invention is not limited thereto, and the number of basic cycles is compared with the number of time slots of each periodic message. It will be apparent to those skilled in the art that categorizing the periodic messages in to one or more sub-message sets and using them to place each periodic message in a given transmission column may be included in the scope of the present invention.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

1 is a view showing the basic structure of the TTCAN basic cycle to which the present invention is applied.

2 is a schematic representation of a first system matrix and a second system matrix in accordance with the present invention;

3 is a diagram schematically illustrating a process of scheduling a TTCAN by a scheduler according to an exemplary embodiment of the present invention.

4 is a flowchart illustrating a detailed process of classifying a lower message set according to the present invention.

5 shows a system matrix by RMS.

6 is a diagram illustrating a system matrix to which a scheduling algorithm according to the present invention is applied.

Claims (14)

TTCAN (Time-Triggered Controller Area Network) scheduling method, Classifying a message found as having a required number of time slots in a periodic message smaller than a number of basic cycles into one or more lower message sets using a predetermined algorithm; And Mapping the messages contained in each subset of messages to the same transport column, Each of the one or more lower message sets is classified based on transmission time and number of time slots, The TTCAN scheduling method of one of the lower message set is that the transmission time of the searched message is the same or when the searched messages are arranged in order according to the transmission time, the messages having the transmission time of the adjacent order are arranged. delete The method of claim 1, The classification step, Sorting the searched messages in descending order according to a transmission time; And A message belonging to a predetermined lower message set using at least one of the number of basic cycles, the number of time slots of each message, the number of basic cycles, and a setting value updated according to the number of time slots in the descending order of messages. TTCAN scheduling method comprising the step of determining. The method of claim 3, The determining step, Generating a first set of lower messages; Comparing the number of time slots and a set value of the first message, wherein the set value is initially set to the number of basic cycles; And And inserting the first message into the first lower message set when the number of time slots of the first message is less than or equal to the set value. In claim 4, The determining step, Updating the setting value by subtracting the number of time slots of the first message from the setting value when the first message is inserted into the first lower message set; And And comparing the updated set value with the number of time slots of a second message when the updated set value is not zero. The method of claim 5, The determining step, When the number of time slots of the second message is larger than the updated set value, the message is searched for a message whose number of time slots is equal to the updated set value among the messages not allocated to the predetermined lower message set to the first lower message set. TTCAN scheduling method further comprising the step of inserting. The method of claim 6, And when the number of timeslots of the messages not allocated to the lower message set is the same as the updated setting value, a message having the largest transmission time is inserted into the first lower message set. The method of claim 6, And generating a second lower message set and determining a message to be inserted into the second lower message set when the updated set value is zero. The method of claim 1, Generating a first system matrix for all periodic messages using ratio monotonic scheduling prior to the classifying step, And the message included in the partial use transmission column in the first system matrix is rearranged through the classification step. TTCAN (Time-Triggered Controller Area Network) scheduling method, Generating a first system matrix for all periodic messages using ratio monotonic scheduling; Searching for a partial use transmission column in the first system matrix; And Relocating a plurality of messages included in the searched transmission column according to a preset algorithm to generate a second system matrix having a minimum maximum window of an exclusive window. The method of claim 10, Generating the second system matrix, Sorting a plurality of messages included in the searched transmission column in descending order according to a transmission time; And Determining one or more sub-message sets to which each message belongs so that empty slots are minimized in consideration of transmission time for the messages arranged in descending order. The method of claim 11, And each of the one or more lower message sets corresponds to a predetermined transmission column of the second system matrix. The method of claim 11, The determining may include: TTCAN scheduling for determining a message belonging to a predetermined lower message set by using at least one of the number of basic cycles, the number of time slots of each message, and the setting value updated according to the number of basic cycles and the number of time slots. Way. delete

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