Joint Motion Parameters Menu
This documentation provides detailed information about the Joint Motion Parameters menu options available in the SPEC utility program. When you select a menu option, the following information is provided on screen:
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Instructions for the specified option
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Current value
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Value range for the parameter
For details on a menu option, click the desired link in the following list to view the description:
Time required to be in tolerance
Tolerance checking filter pole
Menu Options
Change Joint Number
Selects another joint for parameter editing. The currently selected joint is displayed in the menu title.
Nulling Tolerances (FINE, COARSE, Time Required, Tolerance checking filter pole)
These menu options allow you to specify nulling tolerances used to determine when a mechanism has reached its final destination.
When a BREAK or DELAY instruction follows a motion instruction, each motor of the robot is required to settle within the specified number of encoder counts for the specified time before the program will continue executing. Note that the FINE and COARSE nulling tolerances are specified in encoder counts which specify motor position and not joint location. The location of the encoder (motor mounted or joint mounted), and the coupling between the encoder and the joint will determine the effective joint nulling tolerance.
FINE nulling tolerance
The encoder count range specified in this parameter will be in effect after a FINE program instruction is executed. These values are normally set slightly greater than the best repeatability that the robot is expected to achieve.
COARSE nulling tolerance
The encoder count range will be in effect after a COARSE program instruction is executed. This tolerance range is normally set equal to 2 to 10 times the size of the FINE tolerance nulling range.
Time Required to be in Tolerance
Determines how long the robot is required to remain within the specified tolerance before the motion is considered complete. This parameter is used when the system attempt to null position errors within either FINE or COARSE tolerance. The recommended value is approximately 0.016 seconds if the tolerance checking filter is not used. If the tolerance filter is used, the recommended value is .008.
Tolerance Checking Filter Pole 1
If this parameter is specified, a low-pass filter is applied to the tracking error during nulling within FINE or COARSE tolerance. It predicts the error trend, and hence, avoids falsely declaring a motion completion. A false nulling declaration may sometimes happen when the servo response is oscillatory. The filter pole works in conjunction with the Time required to be in tolerance parameter. The recommended filter pole value is 4 with the Time required to be in tolerance set at .008.
NOTE: (The FINE and COARSE parameters can also be edited in the restricted-access mode of SPEC, as described in Instructions for Adept Utility Programs.)
READY Position
Specifying this parameter defines a READY location that should be close to the middle of the robot workspace and safely away from the workcell hardware. When calibrated, the robot can be easily moved to the READY position with a "READY" program instruction.
Joint Speed and Acceleration
These parameters define the joint speed and acceleration at which a joint will travel when executing a joint interpolated move, as commanded by the MOVE or DRIVE program instructions. The joint speed parameter defines the top speed at which the joint will move at SPEED 100, and the acceleration parameter sets the acceleration rate at ACCEL 100,100. Refer to the Cartesian Motion Parameters menu for information on straight-line motion parameters.
JOINT Pendant Increment and Speed
If the SLOW button on the manual control pendant (MCP) is pressed and the speed pot is pressed close to its center (minimum plus or minus speed), the robot will move the smallest specified increment and then stop. If the speed is increased, the robot will begin to move at a continuous rate equal to five times the smallest incremental motion per second. As the commanded speed is increased, the robot's speed will linearly increase until the robot is moving at 25% of the maximum specified speed. If the SLOW button is turned off, the robot's speed will be linearly interpolated between zero and the maximum specified speed.
WARNING: RIA (Robot Industries of America, USA) safety standards require that mechanical devices not exceed a tool tip speed of 76.2 millimeters per second (3 inches per second) when operated under manual control. Some other national regulations may require an even lower speed. Be sure to set both the maximum Cartesian translational and the maximum joint manual control speeds so the tool tip cannot exceed this limit even with the robot at full extension.
FREE Mode Configuration Parameters
Selecting FREE mode on the MCP "frees" the selected joint by zeroing the motor torque and optionally releasing a clutch. This mode is intended to allow the mechanism to be easily moved by hand during setup and location teaching. When a joint is gravity-loaded, FREE mode may be undesirable since the joint could drop, causing damage to the payload or the workspace. The FREE mode parameter can be used to disable FREE mode in this situation.
Certain mechanical designs such as gearboxes, harmonic drives, etc., may not allow the axis to be easily moved manually even when the motor torque is zeroed. The only way to easily move such a joint manually is through the use of a mechanical clutch to disengage the axis to the drive mechanics. The Free Mode Digital Signal parameter may be used to specify which digital output controls the clutch. If a clutch is to be used, the encoder must remain mechanically coupled to the joint so the system does not lose track of the joint position when it is moved.
Velocity Servo
When an axis is placed into FREE manual control mode, the software commands a zero output to the DAC. If the servo uses a current command amplifier, then this will in fact free the joint. An axis which uses a velocity command amplifier (tachometer feedback through the amplifier) will not be free when the DAC output is zero, since the tachometer loop is still closed. If the Velocity Servo switch is enabled, then during FREE manual control mode, Drive Enable will be disabled, thus freeing the axis. In a split axis system, both amplifiers will be disabled.
Joint Limits
Software joint limits (soft stops) can be defined for each joint. After the robot is calibrated, it is not possible to exceed the limits under program or pendant control. These limits are often set just inside of the hardware limit switches. Even though V+ should prevent the robot from moving beyond the soft stops during normal operation, safety considerations require that hardware limit switches also be used.
WARNING: Be sure to properly set the software joint limits before attempting to move the robot with a V+ program. It is especially important for revolute axes to have proper software limits set before attempting any motion instruction. If the limits are improperly set, a revolute axis can rotate unexpectedly in order to stay in range.
V+ prevents you from moving outside the lower and upper joint limit during normal operation. These joint limits can also be configured by the end customer using this program in restricted-access mode (that is, without entering a password) to protect the robot joints from colliding with custom workcell hardware. However, SPEC does not allow setting joint limits outside the range specified by the minimum and maximum joint limits. These extremes should be set by the robot developer to prevent the robot from damaging itself. On a password protected robot, the maximum and minimum joint limits can only be changed after entering the correct password. (Instructions for Adept Utility Programs describes the restricted-access mode of SPEC.)
Joint Mechanism ID
If specified, this parameter is used to trigger special initialization for Adept supported dual-encoder feedback mechanism, such as the Z-theta module. Or, for to enable the custom safety feature for a PUMA device module. Normally, this value should not be modified.
