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--- marvin:lab7 [2008/11/07 10:26] – sohn
+++ marvin:lab7 [2008/11/07 10:58] (current) – rieper
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 ====Project Goal====
-The project goal is to build and experiment with Braitenberg vehicles. The vehicles are shown here below. We aim to reach an expected behaviour of the vehicles, which is introduced and evaluated during the experiments. Tom Dean has written about this subject and these notes can be found [[http://www.cs.brown.edu/people/tld/courses/cs148/02/introduction.html|here]] and [http://www.cs.brown.edu/people/tld/courses/cs148/01/vehicles/vehicles.htm|here]
+The project goal is to build and experiment with Braitenberg vehicles. The vehicles are shown here below. We aim to reach an expected behavior of the vehicles, which is introduced and evaluated during the experiments. Tom Dean has written about this subject((Tom Dean, Introduction to Machina Speculatrix and Braitenberg Vehicles [[http://www.cs.brown.edu/people/tld/courses/cs148/02/introduction.html]])) ((Tom Dean, Notes on construction of Braitenberg's Vehicles, Chapter 1-5 of Braitenbergs book [[http://www.cs.brown.edu/people/tld/courses/cs148/01/vehicles/vehicles.htm]]))
 {{:marvin:lab7-1.gif}}
 ===Vehicle 1===
-This vehicle is utilizes the simplest form of sensor->actuator activation. For this vehicle we shall replica a sensor/actuator system, which originally was connected through a wire-circuit in analog form, where the sensor signal presumably was amplified using transistor or operational amplifiers and fed to the motor. The vehicle behaviour is very simple. The more measured quantity from the sensor the more power is fed to the engine. In theory the sensor input is proportional to the sensor output, but in practice this relationship may not hold due to the sensor characteristic. Our objective is to implement this behavior in a digital form using the LEGO mindstorm NXT module in which we are able program this proportional relationship between sensor and actuator in a java based environment.
+This vehicle utilizes the simplest form of sensor->actuator activation. For this vehicle we shall replica a sensor/actuator system, which originally was connected through a wire-circuit in analog form, where the sensor signal presumably was amplified using transistor or operational amplifiers and fed to the motor. The vehicle behaviour is very simple. The more measured quantity from the sensor the more power is fed to the engine. In theory the sensor input is proportional to the sensor output, but in practice this relationship may not hold due to the sensor characteristic. Our objective is to implement this behavior in a digital form using the LEGO mindstorm NXT module in which we are able program this proportional relationship between sensor and actuator in a java based environment.
 In our project a sound sensor is used instead of a light sensor.
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 **Observed behaviour**\\
-The first testrun indicated that we are facing a motor problem, which have occured often. The problem is, that the car is unable to move forward due to uneven velocity between the motors at the same power level. This problem makes it very difficult to draw conclusions on wheater the code, the sensor or the motors are causing unexpected behaviour. We have attempted to solve this problem by introducing different types of parameters two compensate for the velocity difference, but the problem seems to be dependent on both battery level and nonlinear to the power level. Therefore we have decided to change to a different set of motors.
+The first testrun indicated that we are facing a motor problem, which have occured often. The problem is, that the car is unable to move forward due to uneven velocity between the motors at the same power level. This problem makes it very difficult to draw conclusions on wheater the code, the sensor or the motors are causing unexpected behaviour. We have attempted to solve this problem by introducing different types of parameters to compensate for the velocity difference, but the problem seems to be dependent on both battery level and is non-linear to the power level. Therefore we have decided to change to a different set of motors.
-Another type of problem is the test environment, which has a relatively high ambient light level due to white walls, sun light and lamps. We have decided to make a testrun in a darker environment as one of the rooms at our lab can be made quite dark. This may help to widen the light sensor reading interval. This test indicated yet another problem in the readings from the two sensors. When light is coming from an angle close to 90 degrees the two sensors produce similar readings and the car moves straight ahead, although  it should be making a 90 degree turn towards the light source. This problem was solved by mounting a barrier between the two sensors as illustrated on the pictures below. This barrier assures that the sensor closest to the light will have a significant higher reading when the vehicle is pointing in a direction away from the light source. The effect of this modification was a highly improved behaviour in terms of the expectations towards vehicle 2a. The test is shown in a video below.
+Another type of problem is the test environment, which has a relatively high ambient light level due to white walls, sun light and lamps. We have decided to make a testrun in a darker environment. This may help to widen the light sensor reading interval. This test indicated yet another problem in the readings from the two sensors. When light is coming from an angle close to 90 degrees the two sensors produce similar readings and the car moves straight ahead, although  it should be making a 90 degree turn towards the light source. This problem was solved by mounting a barrier between the two sensors as illustrated on the pictures below. This barrier assures that the sensor closest to the light will have a significant higher reading when the vehicle is pointing in a direction away from the light source. The effect of this modification was a highly improved behaviour in terms of the expectations towards vehicle 2a. The test is shown in a video below.
 **Video and pictures of vehicle 2a**\\
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 ===Interaction between robots===
-A light sensor has been placed on our robot. If we get acces two more robots it would be a nice experiment to place them in a dark room and observe their behaviour. Perhaps it could reflect more complex behaviour that expected given the very simple controllers.
+A light sensor has been placed on our robot. If we get access to more robots it would be a nice experiment to place them in a dark room and observe their behaviour. Perhaps it could reflect more complex behaviour than expected given the very simple controllers.
 ===Conclusions===
-For both vehichles it was possible to make the robots resemble the expected behaviour of the Braitenberg vehicles, 1 & 2a. The sensors need not be the exact same as in the original proposal in order to reach as similar behaviour/sensor->actuator control. Using a microphone for vehicle 1 and light sensor for vehicle 2a combined with a digital control the experiments proved to be succesful in terms of the project goal.
+For both vehichles, it was possible to make the robots resemble the expected behaviour of the Braitenberg vehicles, 1 & 2a. The sensors need not be the exact same as in the original proposal in order to reach as similar behaviour/sensor->actuator control. Using a microphone for vehicle 1 and light sensor for vehicle 2a combined with a digital control the experiments proved to be successful in terms of the project goal.