Force Sense Control - Mitsubishi Electric 4F-FS001-W200 Instruction Manual

8 Using the Force Sense Function (Programming)

8.1 Force Sense Control

The force sense control function is used to control robot softness and push force. Depending on the application,
this function switches between "force control" and "stiffness control". The characteristics of each type of control
are described below.
(1) Force control
This control mode controls the robot while pushing with a specified force. The robot moves automatically to the
position at which the specified reaction force can be obtained.
The robot can be moved while pushing the workpiece with constant force and maintaining the contact status.
Force control has the following 2 modes.
<Speed priority mode>
If no contact has been made with the target object, the robot switches to speed control mode and moves at the
specified speed toward the object.
<Force priority mode>
If contact has been made with the target object, the robot switches to force control mode and the robot is
controlled in order that the specified reaction force can be obtained.
(2) Stiffness control/limited stiffness control
This control mode is used to control the robot softly like a spring. By applying external force, the robot moves
automatically in the direction that allows it to escape the external force.
This type of control can be used to suppress the force acting on the workpiece when performing insertion work.
Furthermore, the robot position is offset while following the assembly part shape, allowing teaching position
displacements to be absorbed.
In the stiffness control, the reaction force will increase in proportion to displacement. If the reaction force is too
large, please set the limit value for the reaction force using the stiffness control with limit.
(3) Position control
This control mode is used to control the robot position. Position control is applied to axes for which neither force
control nor stiffness control are specified.
 Offset and offset speed restrictions 
The restrictions shown in "Table 8-2" are applied to positional offset and offset speed for force sense
control. The positional offset restriciton can be changed in parameter FSCORMX.
Positional offset restriction
Speed offset restriction
(Automatic)
Speed offset restriction
(Manual)
8-46 Force Sense Control
Table 8-2: Offset restrictions
X,Y,Z A,B,C
10 [mm] 10 [deg]
80 [mm/s] 80 [deg/s]
Approx.8 [mm/s] Approx 8 [deg/s]
Remarks
Can be changed in FSCORMX.