eeros_architecture:sequencer:sequence
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
eeros_architecture:sequencer:sequence [2017/08/16 09:53] – [Simple Example] graf | eeros_architecture:sequencer:sequence [2018/08/07 14:20] – external edit 127.0.0.1 | ||
---|---|---|---|
Line 5: | Line 5: | ||
A main feature of a sequence is whether it blocks the flow of control during running through its steps or whether the steps run in parallel to the main flow of control. | A main feature of a sequence is whether it blocks the flow of control during running through its steps or whether the steps run in parallel to the main flow of control. | ||
[{{ : | [{{ : | ||
- | Sequence A runs. That is, all its steps run consecutively. After step 1 is done the sequence B is called. As B is blocking its two steps run while A is being blocked. Only after B finishes does the control return back to A where step 2 and step 3 are then executed. After this sequence C is called. As C is nonblocking its two steps run in parallel to the remaining steps of sequence A. A must wait for C to finish by calling //join//. \\ | + | Sequence A runs. That is, all its steps run consecutively. After step 1 is done the sequence B is called. As B is blocking its two steps run while A is being blocked. Only after B finishes does the control return back to A where step 2 and step 3 are then executed. After this sequence C is called. As C is nonblocking its two steps run in parallel to the remaining steps of sequence A. A must wait for C to finish by calling //wait()//. \\ |
- | A nonblocking sequence will run in its own thread of execution while a nonblocking | + | A nonblocking sequence will run in its own thread of execution while a blocking |
- | IMPORTANT The main sequence must always be defined as nonblocking. Otherwise, the main program | + | IMPORTANT The main sequence must always be defined as nonblocking. Otherwise, the flow of control |
===== Sequence and Step ===== | ===== Sequence and Step ===== | ||
- | Every step is itself basically a sequence. However, a step is always blocking. All the other features such as preconditions and exit conditions as well as monitors are identical, see below. A user has to define her own sequences or steps with: | + | Every step is itself basically a sequence. However, a step is always blocking. All the other features such as preconditions and exit conditions as well as monitors are identical, see below. A user has to define her own sequences or steps as described in [[.:define_sequence|]]. |
- | - Extend class // | + | |
- | - Implement the function // | + | |
- | - Implement the ()-operator with parameters. This ensures that calling a sequence or step with parameters (e.g. step1(10, 3)) is possible. | + | |
Line 22: | Line 20: | ||
- Every sequence starts by checking the preconditions for this sequence to be met. If the test fails the sequence will immediately stop. | - Every sequence starts by checking the preconditions for this sequence to be met. If the test fails the sequence will immediately stop. | ||
- | - The main work of the sequence is done in the function // | + | - The main work of the sequence is done in the function // |
- The sequence than repetively checks for its exit condition to become true. As long as this is not the case, the sequence or step stays in this loop. | - The sequence than repetively checks for its exit condition to become true. As long as this is not the case, the sequence or step stays in this loop. | ||
- In parallel to checking the exit condition the monitors of each sequence are also checked. For monitors see [[.: | - In parallel to checking the exit condition the monitors of each sequence are also checked. For monitors see [[.: | ||
Line 31: | Line 29: | ||
class Move : public Step { | class Move : public Step { | ||
public: | public: | ||
- | Move(std:: | + | Move(std:: |
int operator() (double x, double y) {xPos = x; yPos = y; return start();} | int operator() (double x, double y) {xPos = x; yPos = y; return start();} | ||
int action() { | int action() { | ||
Line 44: | Line 42: | ||
class MoveSequence : public Sequence { | class MoveSequence : public Sequence { | ||
public: | public: | ||
- | MoveSequence(std:: | + | MoveSequence(std:: |
int action() { | int action() { | ||
robot.moveXY(10, | robot.moveXY(10, | ||
Line 55: | Line 53: | ||
</ | </ | ||
- | The sequence moves a hypothetical robot in x,y direction. | + | The sequence |
+ | |||
+ | ===== Waiting for Sequences to Finish ===== | ||
+ | Usually at some stage in your program you have to wait for a given sequence to finish until the program should continue. There are two methods to accomplish this, '' | ||
+ | The former waits for a given sequence to finish running. It returns as soon as all the steps defined in the sequence have completed to run. However, it does not terminate the associated thread. This allows to restart the same sequence with '' | ||
+ | On the other hand, '' | ||
+ | IMPORTANT Never use '' | ||
eeros_architecture/sequencer/sequence.txt · Last modified: 2020/05/22 11:08 by ursgraf