Arch Statement
Defines or displays the Arch parameters for use with the Jump, Jump3, Jump3CP instructions.
Syntax
(1) Arch archNumber, departDist, approDist
(2) Arch archNumber
(3) Arch
Parameters
- archNumber
- Specify the arch number as an integer from 0 to 6. Valid Arch numbers are from 0 to 6 making a total of 7 entries into the Arch table. (see default Arch Table below)
- Depart Distance
- Specify the depart distance (vertical distance from the starting point) before the horizontal move is executed by the Jump instruction. (specified in millimeters) For Jump3 and Jump3CP, it specifies the depart distance before a span motion. (Unit: mm)
- Approach Distance
- Specify the approach distance (vertical distance from the target point) at the stage when the horizontal movement is completely finished by the Jump instruction. (specified in millimeters)
For Jump3 and Jump3CP, it specifies the approach distance before a span motion. (specified in millimeters)
Return Values
Displays Arch Table when used without parameters.
The Arch table of the specified Arch number will be displayed when only the Arch number is specified.
Description
The primary purpose of the Arch instruction is to define values in the Arch Table which is required for use with the Jump motion instruction. The Arch motion is carried out per the parameters corresponding to the arch number selected in the Jump C modifier. (To completely understand the Arch instruction, the user must first understand the Jump instruction.)
The Arch definitions allow the user to "round corners" in the Z direction when using the Jump C instruction. While the Jump instruction specifies the point to move to (including the final Z joint position), the Arch table entries specify how much distance to move up before beginning horizontal motion (riseDist) and how much distance up from the final Z joint position to complete all horizontal motion (fallDist). (See the diagram below)
| Symbol | Description |
|---|---|
| a | Depart Distance |
| b | Approach Distance |
There are a total of 8 entries in the Arch Definition Table with 7 of them (0-6) being user definable. The 8th entry (Arch 7) is the default Arch which actually specifies no arch at all which is referred to as Gate Motion. (See Gate Motion diagram below) The Jump instruction used with the default Arch entry (Entry 8) causes the arm to do the following:
- Begin the move with only Z-joint motion until it reaches the Z-Coordinate value specified by the LimZ command. (The upper Z value)
- Next move horizontally to the target point position until the final X, Y and U positions are reached.
- The Jump instruction is then completed by moving the arm down with only Z-joint motion until the target Z-joint position is reached.
Gate Motion (Jump with Arch 7)
Arch Table Default Values
| Arch Number | Depart Distance | Approach Distance |
|---|---|---|
| 0 | 30 | 30 |
| 1 | 40 | 40 |
| 2 | 50 | 50 |
| 3 | 60 | 60 |
| 4 | 70 | 70 |
| 5 | 80 | 80 |
| 6 | 90 | 90 |
Notes
Another Cause of Gate Motion
When the specified value of the Rising Distance or Falling Distance is larger than the actual Z-joint distance which the robot must move to reach the target position, Gate Motion will occur. (i.e. no type Arch motion will occur.)
Arch values are maintained
The Arch Table values are permanently saved and are not changed until either the user changes them.
Caution for Arch motion
Jump motion trajectory is comprised of vertical motion and horizontal motion. It is not a continuous path trajectory. The actual Jump trajectory of arch motion is not determined by Arch parameters alone. It also depends on motion and speed.
- In a Jump trajectory, the depart distance increases and the approach distance decreases when the motion speed is set high. When the fall distance of the trajectory is shorter than the expected, lower the speed and/or the deceleration, or change the fall distance to be larger.
- Always use care when optimizing Jump trajectory in your applications. Execute Jump with the desired motion and speed to verify the actual trajectory. When speed is lower, the trajectory will be lower. If Jump is executed with high speed to verify an arch motion trajectory, the end effector may crash into an obstacle with lower speed.
- Even if Jump commands with the same distance and speed are executed, the trajectory is affected by motion of the robot arms. As a general example, for a SCARA robot the vertical upward distance increases and the vertical downward distance decreases when the movement of the first arm is large. When the vertical fall distance decreases and the trajectory is shorter than the expected, lower the speed and/or the deceleration, or change the fall distance to be larger.
See Also
Jump, Jump3, JumpCP
Arch Statement Example
The following are examples of Arch settings done from the command window.
> arch 0, 15, 15
> arch 1, 25, 50
> jump p1 c1
> arch
arch0 = 15.000 15.000
arch1 = 25.000 50.000
arch2 = 50.000 50.000
arch3 = 60.000 60.000
arch4 = 70.000 70.000
arch5 = 80.000 80.000
arch6 = 90.000 90.000
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