Identify the force control directions Sf and motion control

Identify the force control directions S_f and motion control directions S_v for the task of using ruler and pencil to draw a straight line as shown in the figure below.

Solution

In the above task of drawing a straight line:

1) The force control direction (S_f ) is nothing but the reaction force direction as the reaction force will always acts in opposite direction to the action force so here the z axis direction represents the \"force control direction\".

2)In the same way the motion control (S_v) is nothing but the reaction force direction acting in opposite to the motion direction so here the y axis direction represents the \" motion control direction\".