Exercise 2. Point-to-Point Programs EXERCISE OBJECTIVE

Transcription

1 Exercise 2 Point-to-Point Programs EXERCISE OBJECTIVE In this exercise, you will learn various important terms used in the robotics field. You will also be introduced to position and control points, and to point-to-point programs. In the Procedure section, you will create, test, and save point-to-point programs using the Hand-Held Terminal. You will program the Servo Robot to bypass obstacles, and you will transfer a program to Robotics. DISCUSSION Work Cell The work cell is the environment in which a robot must perform its tasks. The equipment included in the work cell may be a controller, robot, computer, work table, safety features, conveyor belt and/or similar devices, and all the equipment required by the robot to do its job is included in the work cell. Work Envelope The work envelope is the path of points that can be reached by a robot. The work envelope of an articulated-arm robot, as the one of your training system, is shown in Figure 2-1. Figure 2-1. Work envelope of an articulated-arm robot. 2-1

2 End Effector The end effector is the hand connected to the arm of a robot. It could be any working mechanisms including a gripper, a grinder, a welding torch, a paint nozzle, a vacuum pump, a scalpel, a blowtorch, or just about anything used to do a job. Some robots can change end effectors and be reprogrammed for a different set of tasks. The end effector of the Servo Robot of your training system is a two-finger mechanical gripper driven by a servo motor. Methods of Programming There are four major methods of programming a robot: manual, lead-through, walkthrough, and software programming. The manual programming method is accomplished by an operator physically setting the necessary end stops, switches, cams, electric wires, or hoses to complete a sequence of steps. This type of programming is characteristic of the less sophisticated robots. In the lead-through programming method, the operator uses a teach pendant to lead the robot through the desired positions. As the robot reaches each desired point in the sequence of motion, the point is saved into memory. The point coordinates correspond to the position of the articulations compared to a reference position. The saved points are used to generate the path the robot follows during operation. In the walk-through programming method, an operator moves the robot through the desired motions. While the operator is moving the robot through the desired path, various points are sampled and saved into memory for a later playback. In the software programming method, the robot is programmed by means of a computer. This method of programming is also known as off-line programming since the programming generally occurs away from the robot. Position Points Position points are records that contain information about the location of each point required to figure out a path that will allow the robot to move without interfacing with other objects to the required locations. The information included in a position point may be the point name, the coordinates of each articulation of the robot, and the speed value. Control Points Control points are records that contain information about the status of the inputs and outputs of the robot controller. The information may also include the point name and the delay value. Control points are used to control the execution of a sequence of points and the operation of external devices. They are saved and inserted in a program as position points. 2-2

3 Point-to-Point Programs Point-to-point programs consist in a list of position and control points. The sequence of points is executed as listed in the point list. Point-to-point programs can be created using the Hand-Held Terminal and Robotics. Task Programs Task programs consist in a list of instruction lines made of points and task commands. Many task commands are usual commands found in programs such as If, Then, Else, While, Do, etc... Other commands are more specific to the Lab-Volt equipment such as Carousel, CNC input, etc... Task commands provide great programming capabilities. This programming mode is explained in more detail in the next exercise. Home Position Programs are usually developed to be used more than once. In order to repeat a program, the equipment must be placed at the same location and orientation as when you created the position points of the program and the Servo Robot must start in the same position. The starting position of the Servo Robot is called the home position. The home position can be a hard home or soft home position. The hard home position is a fixed reference point where a robot goes to reset the parameters of its motors in starting mode. A hard home positioning is required at the beginning of each session. The soft home position is a position that you assign the robot. It corresponds to the position from where the robot starts its movements. After completing all the assigned tasks, this is the position where the robot will come to rest when you tell it to go home. You can vary the soft home position according to the tasks you want to perform with the robot. Procedure Summary In the first part of the exercise, Set-up, you will install and connect the equipment. In the second part, Creating a Point-to-Point Program, you will create a point-to-point program using the Hand-Held Terminal point. In the third part, Testing a Point-to-Point Program, you will test your point-to-point program. In the fourth part, Saving a Point-to-Point Program, you will save your point-to-point program to a USB drive using the Hand-Held Terminal. In the fifth part, Deleting Points, you will clear all points stored in the Robot Controller memory, and you will use the Point Editor to check the deletion. 2-3

4 In the sixth part, Loading a Point-to-Point Program, you will load the point-to-point program saved previously. In the seventh part, Importing a Point-to-Point Program in Robotics, you will copy the content of the Robot Controller memory into the Point Editor of Robotics. In the last part of the exercise, Shutdown Procedure, you will shut down the system. EQUIPMENT REQUIRED Refer to the Equipment Utilization Chart, in Appendix A of this manual, to obtain the list of equipment required to perform this exercise. PROCEDURE CAUTION! When you work with moving equipment, make sure you are not wearing anything that might get caught, such as a tie or jewelry. If your hair is long, tie it out of the way. Set-up G 1. Install the Servo Robot as shown in Figure 2-2. G 2. Place a film canister at position (R11,C5) and a metallic can at position (R8,C8). Note: The metallic can is used as an obstacle between positions (R11,C5) and (R5,C11). Add a few coins in the film canisters to improve stability. 2-4

5 Figure 2-2. Location of the equipment on the Work Surface. G 3. Make sure that the emergency stop button is released (in the up position) and easily accessible. G 4. Connect the equipment as shown in Appendix B. Refer to the User Guide of your training system for detailed instructions. Note: If the cables have already been installed by your instructor or classmates, verify each connection. Creating a Point-to-Point Program G 5. Connect the USB drive to the controller. Turn on the Robot Controller by setting its power switch at the I (on) position. Note: Perform the following steps using the Hand-Held Terminal. G 6. Execute a hard home positioning. 2-5

6 Point-to-Point Programs G 7. Set the speed at 80. G 8. Fully open the gripper and place it 50 mm (2 in) above the film canister at position (R11,C5) as shown in Figure 2-3. Save the point by performing the following steps: & Press the & key to open the Save Position window. & Press the Enter key if you accept the default name or enter a new name before pressing the Enter key. Figure 2-3. Gripper position. G 9. To help you to position and grip the film canister with precision, reduce the speed at 10. G 10. Lower the gripper and grip the film canister as shown in Figure 2-4 without saving the point. Figure 2-4. Gripping the film canister with the gripper. 2-6

7 Once the gripper position is adjusted correctly, open the gripper. Save the point. G 11. Close the gripper to grip the film canister. Do not grip the film canister too tightly. Save the point. Note: This procedure is required to prevent the gripper from closing too early. If you save the point with the gripper closed (with the part in the gripper) without saving a point with the gripper open first, the closing movement of the gripper will start from the last point that you have saved. The gripper will arrive almost closed and might not be able to grip the film canister. G 12. Set the speed at 80. G 13. Raise the film canister 20 cm (8 in) above the Work Surface. Save the point. Note: The path followed by the gripper to move an object from a position to another is not memorized by the Robot Controller. When programming a sequence of movements, you have to define each point required to figure out a path that will allow the Servo Robot to move without interfacing with other objects. Figure 2-5 shows how to bypass an obstacle. Figure 2-5. Bypassing an obstacle. G 14. Rotate the shoulder of the Servo Robot to move the film canister horizontally above position (R5,C11). Do not lower the film canister now. Save the point. G 15. Lower the film canister 50 mm (2 in) above the Work Surface. Save the point. 2-7

8 G 16. Set the speed at 10. G 17. Lower the film canister at position (R5,C11) without opening the gripper. Save the point. Note: Before opening the gripper to release a part, you must save a point with the part still in the gripper. If you do not save this point, the opening movement of the gripper will start from the last point you saved and the part will fall down somewhere between the two points when executing the program. G 18. Set the speed at 80. G 19. Open the gripper to release the film canister on the Work Surface. Save the point. G 20. Raise the gripper 20 cm (8 in) above the Work Surface. Save the point. Testing a Point-to-Point Program G 21. Replace the film canister at position (R11,C5) manually. G 22. Test your point-to-point program by performing the following steps: In the Main menu, press the 2 key to select Task Manager. Press the 1 key to select Run Once. This will cause the Servo Robot to move to the home position, execute all points sequentially, return to the home position, and stop. G 23. Did the point-to-point program execute as predicted? G Yes G No Note: At the end of the program, the Servo Robot returns to the home position. This position corresponds to the hard home position when no soft home position is assigned. G 24. Remove the film canister from position (R5,C11) manually. Press the Run Forever key to repeat the execution (without film canister). While the Servo Robot moves from point-to-point, observe the display of the Hand-Held Terminal. It shows the number of times that the point sequence has been repeated and the point that is being executed. 2-8

9 Once your observation is completed, press the Esc key to abort the execution. Saving a Point-to-Point Program G 25. Save your point-to-point program by performing the following steps: In the Main menu, press the 3 key to select File Manager. In the File menu, press the 1 key to select Save to Disk. Specify where you want to save your file by selecting either of the two available options: 1 INTERNAL DRIVE 2 USB DRIVE Note: The USB drive must be connected to the controller before turning on the controller. If you select the option ''2 USB DRIVE'' when no USB drive is connected to the controller, the following message will be displayed: 2 NO USB DRIVE. To solve this problem, save your file on the internal drive, turn off the controller, connect the USB drive, then turn on the controller. Use option 3 MOVE FILE TO USB to save your file on the USB drive. In the Save File menu, use the left arrow key to delete the default name and enter EXE_2_A as the name of your program. Note: Use the Shift key to access the characters in the dark blue section of the keys. The character _ corresponds to the space function on the keypad. Press the Enter key to save the program. Note: Refer to the User Guide for a more complete description on how to save a point-to-point program using the Hand-Held Terminal. Deleting Points G 26. Clear all points in the Robot Controller memory by performing the following steps: In the Main menu, press the 2 key to select Task Manager. Press the 4 key to select Clear Points. Press the Enter key to confirm your choice. All points previously stored in the Robot Controller memory are now deleted. To confirm the deletion, press the 1 key in the Main menu to select Point Manager. If the points are deleted, only the Home point will be displayed. 2-9

10 Loading a Point-to-Point Program G 27. Load your point-to-point program from the USB drive by performing the following steps: In the Main menu, press the 3 key to select File Manager. Press the 2 key to select Load from Disk. Select either of the following locations: 1 INTERNAL DRIVE 2 USB DRIVE Press the Enter key to confirm your choice. Place the cursor beside the file corresponding to the program named EXE_2_A, and press the Enter key. Your point-to-point program is now stored in the Robot Controller memory. To confirm the loading process, press the 1 key in the Main menu to select Point Manager. The point list should be displayed. Importing a Point-to-Point Program in Robotics G 28. Copy your point-to-point program from the Robot Controller memory to the Point Editor window in Robotics by performing the following steps: Launch Robotics. Select Online in the Robot menu to enable the control of the Servo Robot from the host computer. In the Upload to sub-menu of the Robot menu, select Point Editor. Click the OK button in the Warning window. The content of the Robot Controller memory will be copied in the Point Editor window. Note: If the Point Editor window was not open, it will automatically open with the list of points in. G 29. Execute the point-to-point program by clicking the Execute button in the Point Editor window. This will cause the Run Point window to open, and the point-to-point program to be executed. Note: Note that the Servo Robot does not return automatically to the home position at the end of the program when it is executed from Robotics. 2-10

11 G 30. Move the point-to-point program from the controller to the USB drive. Shutdown Procedure G 31. Make sure that there is nothing inside the gripper. G 32. Clear the area around the Servo Robot so that it will not hit anything when it moves. G 33. Execute a hard home positioning using the Hand-Held Terminal or Robotics as desired. G 34. Turn off the Robot Controller by setting its power switch at the O (off) position. G 35. Disconnect the system and return the equipment to its storage location. CONCLUSION In this exercise, you were introduced to various terms used in the robotics field. You created a point-to-point program using the Hand-Held Terminal. You tested the program and saved it on the USB drive without using the host computer. You learned also to transfer a program from the Robot Controller memory to the Point Editor window of Robotics. REVIEW QUESTIONS 1. To reset the articulated sections of the Servo Robot to their original position, you... a. Execute a hard home positioning. b. Torque the motors. c. Execute a hardware reset. d. Free Motors. 2. Which menu is used to manipulate the Servo Robot and save points? a. Teach menu. b. Main menu. c. File menu. d. Motion Control menu. 2-11

12 3. The path of points that can be reached by a robot is named a. Work cell. b. Work envelope. c. Point-to-point program. d. Program. 4. When is it required to reduce the speed of the Servo Robot? a. When making precise moves. b. When making large moves. c. When opening the gripper. d. When executing a hard home positioning. 5. The starting position of the Servo Robot is called a. Starting point. b. Rest position. c. Origin. d. Home position. 2-12