Force Mode Ctrl

Use this command to apply a force in a particular direction instead of maintaining/following a reference position.

Fieldbus Interface

PMC_ForceModeCtrl

Inputs

Name	Data Type	Description
Execute	BOOL	Execution of the function block begins on a rising edge of this input.
Mode	USINT	0: Absolute Force Mode; 1: Relative Force Mode (relative to current force output in the specified axis)
Level	USINT	0: Exit Force Mode 1: Z axis force mode 2: X axis force mode 3: Y axis force mode 4: X&Y axis force mode 5: Z torque Mode 8: X force + Z Torque mode 9: Y force + Z Torque mode 11: X force + Y force + Z Torque
Buffer	USINT	0: Enter / exit force mode immediately 1: Enter / exit force mode command will be added to the specified mover's motion buffer. If an enter force mode command is added to a macro, then an exit force mode command must also be added after it. If not, an exit force mode command will be automatically added at the end of the macro
XbotID	USINT	ID of the XBot. Real XBot IDs [1,78].
ForceX	REAL	When applicable, the desired X force in Newtons.
ForceY	REAL	When applicable, the desired Y force in Newtons.
ForceZ	REAL	When applicable, the desired Z force in Newtons.
TorqueZ	REAL	When applicable, the desired torque in Rz in Newton-meters.
PM_Controller	PMControllerType	Data structure that specifies which PMC to connect to. There should be only 1 instance of this variable for each connected PMC.

Outputs

Name	Data Type	Description
Done	BOOL	Execution successful. Function block is finished. (Note: Done will not become TRUE if Execute is already FALSE)
Busy	BOOL	Function block is active and must continue to be called.
Aborted	BOOL	Command aborted by another command.
Error	BOOL	If there is an error in processing the command, then Error = TRUE, otherwise, FALSE.
ErrorID	UINT	0x0: All OK. Otherwise, please see PMC Reply Codes.

Conditions

Operating Conditions
Preconditions	XBot is in the Idle state, Obstacle Detected state, Motion state, Stopped state, Hold Position state, or Waiting state.
Postconditions	The XBot will enter or exit Force Mode, as specified

Description

Use this command to apply a force in a particular direction instead of maintaining/following a reference position.

The force command allows the user to apply a force in a chosen orientation, while disabling position control in that direction. While the XBot is in force mode, it is possible to move the XBot using the linear motion command as long as the axes affected by the motion command are not in force mode.

Force feedback is provide through the Get XBot Status command. See also Configure Feedback Stream and Read Xbot Force

Force mode command is specified by providing the X, Y, Z, RX, RY, RZ components of the desired force/torque. Currently, only X, Y, Z force component can be non-zero.

When entering force mode, the total Z force provided to the XBot is immediately changed to the value specified in the command. If the XBot is not externally constrained in the Z direction, then the XBot will begin to dive if the force provided is not enough to maintain the current XBot Z position, or the XBot will begin to shoot up if the force provided is higher than what is required to maintain the current XBot Z position.

The recommend procedure is:

Check the Z force feedback prior to entering Force Mode
Specify a Z force value in the force mode command close to the feedback value above, in order to achieve smooth motion during the switch from position mode to force mode
Once in force mode, additional force mode commands can be used to change the force according to application needs

When in Force Mode, if the XBot Z position exceeds 2mm, then it will automatically switch back to Position Mode with reference position Z = 2mm. Similarly, if the XBot Z position decreases below 1mm, then it will switch back to Position Mode with reference position Z = 1mm.

Behaviour During Obstacles

If Force Mode is enabled in Z only, the XBot will still be able to resume its motion in the event of an obstacle. Otherwise, the XBot will enter the Stopped State and its motion will not be resumed even if the obstacle XBot is moved away. The motion command needs to be sent again.

Changelog

PMC v11687 - added Buffer Input option