Listing of the computer program that is used to accept the values and to display them on the screen. For clarity only the code pertaining to the logic is listed. The complete file and the rest of the project are available at the download section.
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// Fill in DCB: 57,600 bps, 8 data bits, no parity, and 1 stop bit.
dcb.BaudRate = CBR_9600; // set the baud rate dcb.ByteSize = 8; // data size, xmit, and rcv dcb.Parity = NOPARITY; // no parity bit dcb.StopBits = ONESTOPBIT; // one stop bit
fSuccess = SetCommState(hCom, &dcb);
if (!fSuccess) { // Handle the error. printf ("SetCommState failed with error %d.\n", GetLastError()); return (3); }
printf ("Serial port %s successfully reconfigured.\n", pcCommPort);
char inBuffer[512], outBuffer[32], outBuffer1[16], outBuffer2[16]; int nBytesToRead = 16; DWORD nBytesRead, nBytesWritten;
while(1) {
ReadFile(hCom, &inBuffer, nBytesToRead, &nBytesRead, (LPOVERLAPPED)NULL); for ( int i = 0; i < nBytesRead; i++ ) printf("%d, ", inBuffer[i]);
Sleep(25); } |
2. Calibration of the Servos
Each Servo is controlled by value between -128 and +127. The speed, however, is not linear, so we have to use a program like the one listed below to determine the optimal speeds for the robot, when going forward, and the differences of speed of the two wheels, for smooth turns.
It is very helpful if the program below is run when the robot is connected to a computer, since we can see the speed output on the screen.
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oDio1 Y = new oDio1; oDio1 R = new oDio1; oDio1 G = new oDio1;
oIRRange LeftMeasure = new oIRRange; oIRRange RightMeasure = new oIRRange; oServoX LeftServo = new oServoX; oServoX RightServo = new oServoX; oSerial com = new oSerial;
oEvent Increase = new oEvent; oEvent Decrease = new oEvent;
Sub void Main(void) { Y.IOLine = 6; Y.Direction = cvInput; oWire increaseSpeed = new oWire; increaseSpeed.Input.Link(Y); increaseSpeed.Output.Link(Increase); increaseSpeed.Operate = cvTrue;
G.IOLine = 5; G.Direction = cvInput; oWire decreaseSpeed = new oWire; decreaseSpeed.Input.Link(G); decreaseSpeed.Output.Link(Decrease); decreaseSpeed.Operate = cvTrue;
R.IOLine = 7; R.Direction = cvOutput; R.Value = 0;
com.Baud = cv9600; com.Operate = cvTrue;
LeftServo.IOLine = 29; RightServo.IOLine = 30; RightServo.InvertOut = cvTrue; RightServo.Value = -20; LeftServo.Value = -20;
LeftServo.Operate = cvTrue; RightServo.Operate = cvTrue;
while(1) {
}
}
Sub void Increase_Code(void) { LeftServo.Value = LeftServo.Value + 1; RightServo.Value = RightServo.Value + 1; com.Value = LeftServo.Value; com.Value = RightServo.Value; R.Value = R.Value - 1;
}
Sub void Decrease_Code(void) { LeftServo.Value = LeftServo.Value - 1; RightServo.Value = RightServo.Value - 1; com.Value = LeftServo.Value; com.Value = RightServo.Value; R.Value = R.Value - 1;
}
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3. Avoid Obstacles with Infrared GP2D120
This first program enables the robot to avoid obstacles detected with one of the mounted infrared sensors – the Sharp GP2D120.
This sensor is fully supported by the OOPic IDE. It can determine the proximity of objects situated between 10cm and 80cm away from the robot.
This is the first step towards the complete avoid obstacles program.
Note: In order for the program to work correctly, the sensors should be put in the exact same positions and pointed at the exact same direction as when originally programmed.
avoid_obstacles_GP2D120.osc
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GP2D120.IOLine = 1; GP2D120.Center = 20; GP2D120.Operate = cvTrue;
Running = 0;
while(1) { /* Check if we have an obstacle in our way */ Avoid_Obstacle(1); } }
Sub void Avoid_Obstacle(Byte Dummy) {
if (Running == 0) return;
RightServo.Operate = cvTrue; LeftServo.Operate = cvTrue;
while (Running) {
//condition "D" //it is enough to check for too close //right since it is common for all three situaions if (GP2D120.Value < TooClose_GP2D120) { //Rotate in place until RightMeasure //is at DistanceFromLeftWall //and LeftMeasure is biger than TooClose_GP2D120 RightServo.Value = -127; while (GP2D120.Value < TooClose_GP2D120 ) { //Rotate in place to the right OOPic.Delay = 20; //in 1/100 of second
} RightServo.Value = 127; } }
RightServo.Operate = cvFalse; LeftServo.Operate = cvFalse;
}
Sub void Go_Code(void) { Running = 1 - Running; } |
4. Avoid obstacles with GP2D120 and GP2D12
This program takes advantage of both sensors that the robot uses like eyes. The sensors differ in their range so they have to be initialized accordingly.
The performance of this program is important since it will show how adequate is the location and direction of each of the sensors which is key factor for the success of the avoid obstacles program.
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oDio1 Y = new oDio1; oDio1 R = new oDio1; oDio1 G = new oDio1; oEvent Go = new oEvent; Byte Running; oServoX LeftServo = new oServoX; oServoX RightServo = new oServoX; oIRRange LeftMeasure = new oIRRange; //GD2D120 oIRRange RightMeasure = new oIRRange; //GD2D12
Const TooClose_LeftSensor = 90; //right wall 30cm Const TooClose_RightSensor = 48; //left wall 30cm Const DistanceFromLeftWall = 70; //about 50cm
Sub void Main(void) { Y.IOLine = 6; Y.Direction = cvInput; oWire GoWire = new oWire; GoWire.Input.Link(Y); GoWire.Output.Link(Go); GoWire.Operate = cvTrue;
R.IOLine = 7; R.Direction = cvOutput; R.Value = 0;
G.IOLine = 5; G.Direction = cvOutput; G.Value = 0;
LeftServo.IOLine = 29; RightServo.IOLine = 30; RightServo.InvertOut = cvTrue; RightServo.Value = 127; LeftServo.Value = 127;
LeftMeasure.IOLine = 1; LeftMeasure.Center = 20; LeftMeasure.Operate = cvTrue;
RightMeasure.IOLine = 2; RightMeasure.Center = 20; RightMeasure.Operate = cvTrue;
Running = 0;
while(1) { /* Check if we have an obstacle in our way */ Avoid_Obstacle(1); } }
Sub void Avoid_Obstacle(Byte Dummy) {
if (Running == 0) return;
RightServo.Operate = cvTrue; LeftServo.Operate = cvTrue;
while (Running) {
//conditions "D","E", "F"; //it is enough to check for too close //right since it is common for all three situaions if (LeftMeasure < TooClose_LeftSensor) { //Rotate in place until RightMeasure //is at DistanceFromLeftWall //and LeftMeasure is biger than TooClose_LeftSensor R.Value = 1; RightServo.Value = -127; while ((RightMeasure.Value < DistanceFromLeftWall) & (LeftMeasure.Value < TooClose_LeftSensor)) { //Rotate in place to the right OOPic.Delay = 20; //in 1/100 of second } RightServo.Value = 127; R.Value = 0; }
//using "ELSE" - each cycle we do only one operation for smoothness else if (RightMeasure.Value < TooClose_RightSensor) { //go slightly right G.Value = 1; RightServo.Value = -127; while(RightMeasure < DistanceFromLeftWall) { OOPic.Delay = 10; } RightServo.Value = 127; G.Value = 0; } }
RightServo.Operate = cvFalse; LeftServo.Operate = cvFalse; }
Sub void Go_Code(void) { Running = 1 - Running; }
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5. Avoid Obstacles – Complete
This is the final version of Avoid Obstacles. An improvement of the programs presented above that allows for demonstration of some independence. Here the robot uses the two sensors to let the robot navigate freely without hitting obstacles, as allowed by its sight.
avoid_obstacles.osc
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oDio1 Y = new oDio1; oDio1 R = new oDio1; oEvent Go = new oEvent; Byte Running; oServoX LeftServo = new oServoX; oServoX RightServo = new oServoX; oIRRange LeftMeasure = new oIRRange; oIRRange RightMeasure = new oIRRange; Const TooCloseLeft = 48; //50cm Const TooCloseRight = 92; //40cm
Sub void Main(void) { //Initialize the button and wire Y.IOLine = 6; Y.Direction = cvInput; oWire GoWire = new oWire; GoWire.Input.Link(Y); GoWire.Output.Link(Go); GoWire.Operate = cvTrue;
R.IOLine = 7; R.Direction = cvOutput; R.Value = 1;
Running = 0;
//Initialize left & right servos LeftServo.IOLine = 29; //LeftServo.InvertOut = cvTrue; LeftServo.Value = 127;
RightServo.IOLine = 30; RightServo.InvertOut = cvTrue; RightServo.Value = 127;
//Initialize left & right IR sensors LeftMeasure.IOLine = 1; LeftMeasure.Center = 20; LeftMeasure.Operate = cvTrue;
RightMeasure.IOLine = 2; RightMeasure.Center = 20; RightMeasure.Operate = cvTrue;
while(1) { //constanlty check if we are in the moving state if (Running) { //Start the servos LeftServo.Operate = cvTrue; RightServo.Operate = cvTrue;
while (Running) { if (LeftMeasure.Value < TooCloseRight) { LeftServo.Value = -127; while (LeftMeasure.Value < TooCloseRight) {
} OOPic.Delay = 50; LeftServo.Value = 127; }
else if (RightMeasure.Value < TooCloseLeft) { RightServo.Value = -127; while (RightMeasure.Value < TooCloseLeft) {
} OOPic.Delay = 50; RightServo.Value = 127;
}
}//end of while loop
RightServo.Operate = cvFalse; LeftServo.Operate = cvFalse;
}//end if }//end while(1)
}//end of Main() function
//control moving/not moving Sub void Go_Code(void) { Running = 1 - Running; } |
6. Move along the wall and avoid obstacles
Besides avoiding obstacles, through OOPic we can make the robot move following a certain pattern. Moving along a wall is a task that is applied often in practical tasks and theoretical problems, like the famous maze problem.
The solution presented includes a new task besides making sure that we do not hit any objects – to monitor a constant distance to the “wall” or set of objects which the robot is moving along.
Below the program listing is a set of diagrams that describe the scheme of the different cases that are used as basis for the solution.
keep_going_along_left_wall_and_avoid_obstacles.osc
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oDio1 Y = new oDio1; oDio1 R = new oDio1; oDio1 G = new oDio1; oEvent Go = new oEvent; Byte Running; oServoX LeftServo = new oServoX; oServoX RightServo = new oServoX; oIRRange LeftMeasure = new oIRRange; oIRRange RightMeasure = new oIRRange;
Const TooClose_LeftSensor = 90; //right wall 30cm Const TooClose_RightSensor = 48; //left wall 30cm Const DistanceFromLeftWall = 70; //about 50cm
Sub void Main(void) { Y.IOLine = 6; Y.Direction = cvInput; oWire GoWire = new oWire; GoWire.Input.Link(Y); GoWire.Output.Link(Go); GoWire.Operate = cvTrue;
R.IOLine = 7; R.Direction = cvOutput; R.Value = 0;
G.IOLine = 5; G.Direction = cvOutput; G.Value = 0;
LeftServo.IOLine = 29; RightServo.IOLine = 30; RightServo.InvertOut = cvTrue; RightServo.Value = 127; LeftServo.Value = 127;
LeftMeasure.IOLine = 1; LeftMeasure.Center = 20; LeftMeasure.Operate = cvTrue;
RightMeasure.IOLine = 2; RightMeasure.Center = 20; RightMeasure.Operate = cvTrue;
Running = 0;
while(1) { /* Check if we have an obstacle in our way */ Avoid_Obstacle(1); } }
Sub void Avoid_Obstacle(Byte Dummy) {
if (Running == 0) return;
RightServo.Operate = cvTrue; LeftServo.Operate = cvTrue;
while (Running) {
//conditions "D","E", "F"; //it is enough to check for too close //right since it is common for all three situaions if (LeftMeasure < TooClose_LeftSensor) { //Rotate in place until RightMeasure //is at DistanceFromLeftWall //and LeftMeasure is biger than TooClose_LeftSensor
RightServo.Value = -127; while ((RightMeasure.Value < DistanceFromLeftWall) & (LeftMeasure.Value < TooClose_LeftSensor)) { //Rotate in place to the right OOPic.Delay = 20; //in 1/100 of second } RightServo.Value = 127;
} //situation "C" //using "ELSE" - each cycle we do only one operation for smoothness else if (RightMeasure.Value < TooClose_RightSensor) { //go slightly right
RightServo.Value = -127; while(RightMeasure < DistanceFromLeftWall) { OOPic.Delay = 10; } RightServo.Value = 127;
}
//if there is no obstacle immediately forward and we are within reasonable deviation //from the DistanceFromLeftWall just go forward (do nothing) else if ((RightMeasure.Value > (DistanceFromLeftWall - 10)) & (RightMeasure.Value < (DistanceFromLeftWall + 2))) { //no instructions; just keep going fwd OOPic.Delay = 20; }
//in case we are we are off course to the right else if (RightMeasure.Value > DistanceFromLeftWall - 10) { //go left LeftServo.Value = 10; G.Value = 1; //while we approach distance and there is no obstacle to the left //continuosly go to the left. This can be changed later by going //in small increments if it produces smoother movement while((RightMeasure.Value > DistanceFromLeftWall) & (LeftMeasure.Value > TooClose_LeftSensor)) { OOPic.Delay = 10; } LeftServo.Value = 127; G.Value = 0; } //in case we are off course to the left else if (RightMeasure.Value < DistanceFromLeftWall + 10) { //go to the right Y.Value = 1; RightServo.Value = -12; while((RightMeasure.Value > DistanceFromLeftWall) & (LeftMeasure.Value > TooClose_LeftSensor)) { OOPic.Delay = 10; } RightServo.Value = 127; Y.Value = 0; } }
RightServo.Operate = cvFalse; LeftServo.Operate = cvFalse; }
Sub void Go_Code(void) { Running = 1 - Running; } |
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7. The PC Control application allows us to control directly the robot from the computer. Using the arrow keys on the keyboard we can make the robot go forward, backwards, go left, right, or turn in place.
There are actually two programs which we need: one is the host program on the robot, which receives the input from the computer, and carries out the necessary commands so that the robot goes in the specified direction. The other program is run at the computer linked to the robot. It accepts the user’s input and then creates output that is suitable for the robot to read.
It is important that the information for the user’s input arrives quickly. This will allow the robot the react promptly and produce smooth movement. For this purpose all the information for the user input is “packed” into one byte.