720 ILCS 5/18-2

(a) A person commits armed robbery when he or she violates Section 18-1; and (1) he or she carries on or about his or her person or is otherwise armed with a dangerous weapon other than a firearm; or (2) he or she carries on or about his or her person or is otherwise armed with a firearm; or (3) he or she, during the commission of the offense, personally discharges a firearm; or (4) he or she, during the commission of the offense, personally discharges a firearm that proximately causes great bodily harm, permanent disability, permanent disfigurement, or death to another person. (b) Sentence. Armed robbery in violation of subsection (a)(1) is a Class X felony. A violation of subsection (a)(2) is a Class X felony for which 15 years shall be added to the term of imprisonment imposed by the court. A violation of subsection (a)(3) is a Class X felony for which 20 years shall be added to the term of imprisonment imposed by the court. A violation of subsection (a)(4) is a Class X felony for which 25 years or up to a term of natural life shall be added to the term of imprisonment imposed by the court.