marvin:lab8
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====Project Goal==== | ====Project Goal==== | ||
Implement a working Rodney Brooks layered control system on the NXT (([[http:// | Implement a working Rodney Brooks layered control system on the NXT (([[http:// | ||
+ | |||
====Plan==== | ====Plan==== | ||
- | * Modify code by Ole Caprani(([[http:// | + | * Modify code by Ole Caprani(([[http:// |
* Test individual behaviors seperately and re-calibrate constants. | * Test individual behaviors seperately and re-calibrate constants. | ||
* Make modular priority system. | * Make modular priority system. | ||
- | * Investegate | + | * Investigate |
+ | |||
+ | ====Execution==== | ||
+ | We modified the code to be more modular. This was not part of the exercise, but it made it a lot easier to test individual modules. Below follows the modifications made. | ||
+ | |||
+ | {{marvin: | ||
+ | * The constant '' | ||
+ | * The constants in the thread '' | ||
+ | **Video of Marvin running with default code**\\ | ||
+ | [[http:// | ||
+ | |||
+ | ===RandomDrive=== | ||
+ | Prints an " | ||
+ | |||
+ | ===AvoidFront=== | ||
+ | Implemented using a sonic sensor. Prints a " | ||
+ | |||
+ | ===PlaySound=== | ||
+ | This thread waits for 10 seconds, then stops and plays a sound while printing an " | ||
+ | |||
+ | ====Modular Priority System==== | ||
+ | The priority handling was in the initial code created by handing pointers to all lower priority behaviour to each behaviour, as shown in the code below: | ||
+ | <code java> | ||
+ | rd = new RandomDrive(" | ||
+ | af = new AvoidFront (" | ||
+ | ps = new PlaySounds ("Play ", | ||
+ | </ | ||
+ | This however makes shuffling of the priorities, as well as making the introduction of new behaviours a very tedious task. We therefore rewrote the priority system to make it more modular and flexible.\\ | ||
+ | Below is the new structure: | ||
+ | <code java> | ||
+ | ArrayList behaviors = new ArrayList(); | ||
+ | |||
+ | RandomDrive rd; | ||
+ | AvoidFront af; | ||
+ | PlaySounds ps; | ||
+ | DriveTowardsLight dl; | ||
+ | |||
+ | rd = new RandomDrive(" | ||
+ | dl = new DriveTowardsLight(" | ||
+ | af = new AvoidFront(" | ||
+ | ps = new PlaySounds(" | ||
+ | </ | ||
+ | The idea is to use an array of Behavior objects containing all lower priority Behaviors in each Behavior.\\ | ||
+ | this array is copied and stored in the constructor of each Behavior, and can then be iterated whenever suppression of the lower levels are needed. | ||
+ | <code java> | ||
+ | private ArrayList behaviors; | ||
+ | |||
+ | public Behavior(String name, ArrayList behaviors) | ||
+ | { | ||
+ | . | ||
+ | . | ||
+ | . | ||
+ | |||
+ | // Clone the Behavior list. | ||
+ | this.behaviors = new ArrayList(); | ||
+ | |||
+ | for(int i = 0; i < behaviors.size(); | ||
+ | Behavior b = (Behavior)behaviors.get(i); | ||
+ | this.behaviors.add(b); | ||
+ | } | ||
+ | } | ||
+ | |||
+ | public void suppressLower() | ||
+ | { | ||
+ | for(int i = 0; i < behaviors.size(); | ||
+ | Behavior b = (Behavior)behaviors.get(i); | ||
+ | b.setSuppress(true); | ||
+ | } | ||
+ | } | ||
+ | </ | ||
+ | The code in its entirety can be found in the '' | ||
+ | |||
+ | ====Java Thread==== | ||
+ | The '' | ||
+ | |||
+ | ====Threaded implementation of " | ||
+ | The '' | ||
+ | The wanted behaviour is the following: | ||
+ | * suppress lower behaviours | ||
+ | * read light values | ||
+ | * assign modified light values as motor power (l1 -> m2, l2 -> m1). | ||
+ | * unsuppress lower behaviours | ||
+ | Here is the most important code from the class: | ||
+ | <code java> | ||
+ | private LightSensor l1; | ||
+ | private LightSensor l2; | ||
+ | private int offset = 60; | ||
+ | |||
+ | public DriveTowardsLight(String name, ArrayList behaviors) | ||
+ | { | ||
+ | ... | ||
+ | l1 = new LightSensor(SensorPort.S2); | ||
+ | l2 = new LightSensor(SensorPort.S3); | ||
+ | l1.setFloodlight(false); | ||
+ | l2.setFloodlight(false); | ||
+ | } | ||
- | http://java.sun.com/ | + | public void run() |
+ | { | ||
+ | while (true) | ||
+ | { | ||
+ | | ||
+ | int val1 = l1.readValue() + offset; | ||
+ | int val2 = l2.readValue() + offset; | ||
- | **Video and pictures** | + | suppressLower(); |
- | [[http://www.youtube.com/ | + | |
+ | delay(500); | ||
+ | unsuppressLower(); | ||
+ | } | ||
+ | </code> | ||
+ | This code however would take over entirely the control of the car since it is active all the time.\\ | ||
+ | We therefore introduced a light threshold to make the car search for light, only when there is some light to search for.\\ | ||
+ | the code for that is shown below: | ||
+ | <code java> | ||
+ | private int threshold = 80; | ||
+ | public void run() | ||
+ | { | ||
+ | . | ||
+ | . | ||
+ | . | ||
+ | if(val1 > threshold || val2 > threshold) { | ||
+ | suppressLower(); | ||
+ | forward(val2, | ||
+ | delay(500); | ||
+ | unsuppressLower(); | ||
+ | } | ||
+ | } | ||
+ | </ | ||
+ | The code in its entirety can be found in the '' | ||
+ | **Video for "Drive towards light test" | ||
+ | [[http:// | ||
- | **Video | + | ====Conclusion==== |
- | [[http:// | + | The layered behavior model seems to work very well for the implementation of an autonomous robot. We believe that with an added push sensor Marvin would be able to navigate in any room avoiding any obstacles and find the exit with lights. |
marvin/lab8.1226057040.txt.gz · Last modified: 2008/11/07 12:24 by rieper