Lab 11: Relative Moves (Palletizing)

1. Lab 11: Relative Moves (Palletizing)

2. Lab 11: Relative Moves

3. Lab 11: Relative Moves (Palletizing)

4. Location Variables: Locations can be specified in two ways in V+: transformations and precision points. A transformation is a set of six components that uniquely identifies a location in Cartesian space and the orientation of the motion device end-of-arm tooling at that location. A transformation can also represent the location of an arbitrary local reference frame. A precision point includes an element for each joint in the motion device. Rotational joint values are measured in degrees; translational joint values are measured in millimeters. These values are absolute with respect to the motion device’s home sensors and cannot be made relative to other locations or coordinate frames.

5. Relative Transformations. (Relative Moves) Relative transformations allow you to make one location relative to another and to build local reference frames to which that transformations can be relative. For example, you may be building an assembly whose location in the workcell changes periodically. If all the locations on the assembly are taught relative to the world coordinate frame, each time the assembly is located differently in the workcell, all the locations must be retaught. If, however, you create a frame based on identifiable features of the assembly, you will have to reteach only the points that define the frame.

6. Transformations: The first three components of a transformation variable are the values for the points on the X, Y, and Z axes. In an Adept SCARA robot, the origin of this Cartesian space is the base of the robot. The Z axis points straight up through the middle of the robot column. The X axis points straight out, and the Y axis runs left to right as you face the robot. The first robot in Figure 8-1 shows the orientation of the Cartesian space for an Adept SCARA robot. The location of the world coordinate system for other robots and motion devices depends on the kinematic model of the motion device.

7. Transformations: For example, the second robot in Figure 8-1 shows the world coordinate frame for a robot built on the Cartesian coordinate model. See the kinematic device module documents for your particular motion device. When a transformation is defined, a local reference frame is created at the X, Y, Z location with all three local frame axes parallel to the world coordinate frame. Figure 8-2 shows the first part of a transformation. This transformation has the value X = 30, Y = 100, Z = 125, yaw = 0, pitch = 0, roll = 0. kinematic Model

8. Transformations: The second three components of a transformation variable specify the orientation of the end-of-arm tooling. These three components are yaw, pitch, and roll. These elements are shown in figures 8-3 through 8-5 demonstrate how these values are interpreted. Yaw Yaw is a rotation about the local reference frame Z axis. This rotation is not about the primary reference frame Z axis, but is centered at the origin of the local frame of reference. Pitch Pitch is defined as a rotation about the local reference frame Y axis, after yaw has been applied Roll Roll is defined as a rotation about the Z axis of the local reference frame after yaw and pitch have been applied.

9. Transformation Instructions: SHIFT: A value can be specified for each component. SHIFT Alters the Cartesian components of an existing transformation. TRANS: The TRANS functions return transformation values. TRANS create a location by specifying individual components of a transformation.

10. SHIFT Instruction: Relative moves are used to move from one precision point. The SHIFT Instruction will change the location point to a new point relative to the last point. The shift instruction performs math addition or substraction of the X, Y, Z, P, R, Y coordinates within a point. The SHIFT instruction is a transformation function. The transformation value is changed by shifting the position of the transformation parameter by the given shift amounts. The value returned is equal to the value of the input transformation parameter value except that the three shift parameter values are added to the X, Y, and Z position components. If any shift parameter is omitted, its value is assumed to be zero.

11. SHIFT Instruction: Syntax SHIFT-T SHIFT (transformation BY x_shift, y_shift, z_shift) Example If the transformation x has the value: (200, 150, 100, 10, 20, 30) then executing the instruction: SET y = SHIFT(x BY 5,-5,10) results in the transformation y receiving the value: (205, 145, 110, 10, 20, 30)

12. Transformation Instructions: SHIFT: A value can be specified for each component. SHIFT Alters the Cartesian components of an existing transformation. TRANS: The TRANS functions return transformation values. TRANS create a location by specifying individual components of a transformation.

13. TRANS Instruction: The TRANS function is also used to transform the values of a point for creating relative moves. It will return a transformation value computed from the given X, Y, Z position displacements and y, p, r orientation rotations. If any parameter is omitted, its value is taken to be zero. The input parameter values are used to compute a transformation value that can be assigned to a location variable or used in a compound transformation or motion request. Syntax: TRANS-T TRANS (X_value, Y_value, Z_value, y_value, p_value, r_value)

14. TRANS Instruction: Examples If r is the radius of a circle and angle is the angle of rotation about the circle, then the transformation: TRANS(r*COS(angle), r*SIN(angle), 0, 0, 0, 0) yields points on that circle. If frame is a transformation defining the position of the center of the circle and the plane in which it lies, the following program segment moves the robot tool point around the circle in steps of 1 degree. FOR angle = 0 TO 360-1 MOVE frame:TRANS(r*COS(angle), r*SIN(angle), 0, 0, 0, 0) END

15. SET Instruction: The SET function is used to set a variable. It is used with the SHIFT or TRANS instruction in a program for relative moves. The SET is used to set the value of the location variable on the left equal to the location value on the right of the equal sign. This is like the old BASIC instruction LET X = ABC location_var Single location variable or compound transformation that ends with a transformation variable. location_value Location value of the same type as the location variable on the left of the equal sign, defined by a variable or function (or compound transformation).

16. SET Instruction: Examples Set the value of the transformation pick equal to the location of corner plus the location of shift relative to corner: SET pick = corner:shift Set the value of the precision point #place equal to that of the precision point #post: SET #place = #post Set the value of the transformation part to the current robot location, relative to the transformation pallet. SET pallet:part = HERE

17.  Examples of Modifying Location Variables Figure 8-6 shows how relative transformations work. The magnitude and direction elements (x, y, z), but not the orientation elements (y, p, r), of an Adept transformation can be represented as a 3-D vector, as shown by the dashed lines and arrows in Figure 8-6. The following code generates the locations shown in that figure. In Figure 8-6, the transformation loc_b defines the transformation needed to get from the local reference frame defined by loc_a to the local reference frame defined by loc_c. Example Page 1

18. Examples of Modifying Location Variables Define a simple transformation SET loc_a = RANS(300,50,350,0,180,0)  Move to the location MOVE loc_a BREAK Move to a location offset -50mm in X, 20mm in Y, and 30mm in Z relative to "loc_a" MOVE loc_a:TRANS(-50, 20, 30) BREAK Define "loc_b" to be the current location relative to "loc_a" HERE loc_a:loc_b ;loc_b = -50, 20, 30, 0, 0, 0 BREAK  Define "loc_c" as the vector sum of "loc_a" and "loc_b" SET loc_c = loc_a:loc_b ;loc_c = 350, 70, 320, 0, 180, 0 Example Page 2

19. Once this code has run, loc_b exists as a transformation that is completely independent of loc_a. The following instruction moves the robot another -50mm in the x, 20mm in the y, and 30mm in the z direction (relative to loc_c): MOVE loc_c:loc_b Multiple relative transformations can be chained together. If we define loc_d to have the value 0, 50, 0, 0, 0, 0: SET loc_d = TRANS(0,50) and then issue the following MOVE instruction: MOVE loc_a:loc_b:loc_d the robot moves to a position x = –50mm, y =70mm, and z = 30mm relative to loc_a. Example Page 3

20. SHIFT Instruction Illustration This example draws a rectangular box Absolute Moves: Teach locations #SAFE and location START Relative Moves: second, third & fourth location offset X coordinate 100 mm offset Y coordinate 125 mm

21. Y - X X -Y SHIFT Instruction Illustration #Safe Move Start Move #Safe Moves Start Start NEW - X Y -Y SET NEW = SHIFT (START BY , 125) Moves NEW SET NEW = SHIFT (NEW BY , - 125) Moves NEW NEW X NEW SET NEW = SHIFT (NEW BY , 100) Moves NEW

22. TRANS Instruction Example (Transformation) This example draw a rectangular box Absolute Moves: Teach locations #SAFE and location START Relative Moves: second, third & fourth location Xval = 100 ; offset for X coordinate Yval = 125 : offset for Y coordinate

23. #Safe Move Start Move #Safe Start NEW - X Y Moves Start - X Y X -Y -Y SET NEW = NEW:TRANS (,-Yval) Moves NEW SET NEW = Start:TRANS (,Yval) Moves NEW NEW NEW X SET NEW = NEW:TRANS (Xval) Moves NEW TRANS Instruction Example (Transformation)

24. #SAFE (HOME) Global M = 31.75 Global NEW Move feeder ; above parts feeder PROMPT “press any key to start”,$key ; Place 4 blocks in first row (Y-Axis) Call Get_Part Set NEW. = BLOCK1 : taught location Call Place_Part 12 FOR R = 1- 4 SET NEW = SHIFT (NEW BY M) Call Get_Part BREAK CALL Place_Part End ; Move X-Axis to next row SET NEW.= SHIFT (NEW BY - 6*M) FOR C = 1- 3 SET NEW = SHIFT (NEW BY 2*M) Goto 12 End .get_part ; SUB to pick up a part from parts feeder Appro pick, 50 Speed 20 Move pick Close I Speed 75 Depart 100 Return .Place_Part ; SUB to place block on the pallet Approach NEW 100 Speed 20 Moves NEW Open I Speed = 75 Depart 100 Return TYPE “ All blocks placed” MOVE #SAFE .end

25. Lab 11: Relative Moves (Palletizing) The End