For an action to be involuntary, there must be some external principle causing the action and the person must not contribute anything to the action. An action done through ignorance is not necessarily involuntary. If the person regrets the action which he did in ignorance, it was involuntary. A voluntary action is one in which the agent of the action knows the particulars on which the action depends. An action performed through temper or desire is still voluntary.
Intention is crucial for virtuous actions and for judgment of character.
Intention is not the same as volition, because non-rational beings can act with volition but not with intention. Intention is not a desire, a wish or an opinion. It is something previously deliberated upon, and is formed with reason or thought. People don't deliberate about matters over which they have no control, but rather about things which they themselves can do. We deliberate about things which are possible, which have an unclear outcome and in which there is something indeterminate.