Resarch Track Assignment-1

first assignment solution Python Robotics Simulator

This is a simple, portable robot simulator modified by me from the exercise given by CarmineD8.

Installing and running

The simulator requires a Python 2.7 installation, the pygame library, PyPyBox2D, and PyYAML.

Once the dependencies are installed, simply run the test.py script to test out the simulator.

The Arena

To run one or more scripts in the simulator, use run.py, passing it the file names. The robot has to drive across the whole arena, in which the golden token reperesent an obstacle to avoid and the silver token the target to move.

Robot API

The API for controlling a simulated robot is designed to be as similar as possible to the [SR API][sr-api].

Motors

The simulated robot has two motors configured for skid steering, connected to a two-output Motor Board. The left motor is connected to output 0 and the right motor to output 1.

The Motor Board API is identical to that of the SR API, except that motor boards cannot be addressed by serial number. So, to turn on the spot at one quarter of full power, one might write the following:

R.motors[0].m0.power = 25
R.motors[0].m1.power = -25

The Grabber

The robot is equipped with a grabber, capable of picking up a token which is in front of the robot and within 0.4 metres of the robot's centre. To pick up a token, call the R.grab method:

success = R.grab()

The R.grab function returns True if a token was successfully picked up, or False otherwise. If the robot is already holding a token, it will throw an AlreadyHoldingSomethingException.

To drop the token, call the R.release method.

Cable-tie flails are not implemented.

Vision

To help the robot find tokens and navigate, each token has markers stuck to it, as does each wall. The R.see method returns a list of all the markers the robot can see, as Marker objects. The robot can only see markers which it is facing towards.

Each Marker object has the following attributes:

• info: a MarkerInfo object describing the marker itself. Has the following attributes:
  • code: the numeric code of the marker.
  • marker_type: the type of object the marker is attached to (either MARKER_TOKEN_GOLD, MARKER_TOKEN_SILVER or MARKER_ARENA).
  • offset: offset of the numeric code of the marker from the lowest numbered marker of its type. For example, token number 3 has the code 43, but offset 3.
  • size: the size that the marker would be in the real game, for compatibility with the SR API.
• centre: the location of the marker in polar coordinates, as a PolarCoord object. Has the following attributes:
  • length: the distance from the centre of the robot to the object (in metres).
  • rot_y: rotation about the Y axis in degrees.
• dist: an alias for centre.length
• res: the value of the res parameter of R.see, for compatibility with the SR API.
• rot_y: an alias for centre.rot_y
• timestamp: the time at which the marker was seen (when R.see was called).

Behaviour Management

After that the robot sees the token, based on the marker_type, it has to run different actions, as described in the flowchart. For this reason, 2 sets of functions are used.

• Actions for the silver token:

  • find_silver token : Function to find the closest silver token.
  • traj_adjustment(rot_y) : Function to adjust the orientation of the robot toward the nearest silver token, takes as argument the orientation about the Y axis in degrees.
  • changeBool(dist, silver) : Function to change the boolean value of the silver token.

• To this set of functions the following variables are related:

  • a_th=2.0 : (float) Threshold for the control of the linear orientation of the silver token alignment.
  • d_th= 0.7: (float) Threshold for the control of the distance from the silver token.
  • s_th=60.0 : (float) Threshold for the control of linear orientation for the silver token perception.
  • silver=True : (boolean) Variable for letting the robot know if it has to look for a silver or for a golden marker.

• Actions for the golden token:

  • find_golden token : Function to find the closest golden token.
  • gold_manage(dist, rot_y) : Function to manage the behaviour of the robot when a golden token is seen in its threshold, takes as argument the distance of the closest golden token and the orientation about the Y axis in degrees.
  • sideView() : Function to check on the side of the robot and choose the side without near golden token.

• To this set of functions the following variables are related:

  • ang_th= 80.0 : (float) Threshold for the control of the linear orientation of the golden token alignment.
  • dist_th=0.8: (float) Threshold for the control of the distance from the golden token.