Defining Travel Limits

You can define travel limits and soft limits for commands within a mechanism. These limits are used during jogging/simulation of a device or mechanism.

The travel limits for robots within the robot catalog are specified by the robot manufacturer. In certain cases, you may wish to enter modified limits, e.g., to avoid a collision. These modified limits are called soft limits; the original limits are called hard limits. If you enter soft limits, those limits become the lower and upper limits for a specific device; if you do not enter any soft limits, the lower and upper limits are the hard limits.

In addition to limits, you can also create a caution zone. Caution zones exist only in CAM software; they are not defined within the robot controller. The purpose of a caution zone is to keep a margin so that a downloaded program will not exceed the limit after calibration or minor changes in the real world.

Previously, the travel limits of joints were defined by numeric values only. Many times lower/upper limits of some particular joints may depend on the current value of other joints. Expressions are useful for defining the limits of any joint in such cases.

Alternatively, you can specify a numeric value for travel limit.

  • Travel Limits: Specified via Upper Limit and Lower Limit, that define the desired valid range for joint's movement.
  • Expression: Arithmetic statement containing trigonometric functions (sin(), cos(), tan(), etc), operators (+, -, *, etc.), and predefined functions (SASS, SSSA, etc.)

More details about operators and functions are available in the Defining Kinematics section.

Expressions are useful for defining the limits of any joint in such cases. This also shows how defining the travel limits of the joints in terms of expressions. Alternatively you can specify a numeric value for travel limit (existing implementation).

  1. From the Motion Controller section of the action bar, select Travel Limits .
  2. Select a device.

    The Travel Limits dialog box appears for the selected device.



    Limits display allows you to choose the types of limits that are shown in the table. You can choose to view or hide Travel limits, Caution zone, and Soft limits.

    Caution zone specifications allows you to specify that Absolute (deg) or Relative (%) values are used with respect to the lowest range limits.

    Note: To input expressions instead of values, click = next to the command name. When clicked, you can enter an expression for both Lower limit and Upper limit. The expression for the travel limits can be defined in terms of the pre-defined functions and operators that are described in Defining Kinematic Relationships.
  3. Set the upper and lower joint limits with the desired values and click OK to close the Travel Limits dialog box.
  4. From the Motion Controller section of the action bar, click Jog Mechanism and select the same device.
    The Jog dialog box appears.
  5. Jog the commands that you have defined limits for, and note the color changes as you reach each defined limit.