▁H IL ▁simulation ▁provides ▁an ▁effective ▁platform ▁by ▁adding ▁the ▁complexity ▁of ▁the ▁plant ▁under ▁control ▁to ▁the ▁test ▁platform . ▁The ▁complexity ▁of ▁the ▁plant ▁under ▁control ▁is ▁included ▁in ▁test ▁and ▁development ▁by ▁adding ▁a ▁mathematical ▁representation ▁of ▁all ▁related ▁dynamic ▁systems . ▁These ▁mathematical ▁representations ▁are ▁referred ▁to ▁as ▁the ▁“ plant ▁simulation ”. ▁The ▁embedded ▁system ▁to ▁be ▁tested ▁interact s ▁with ▁this ▁plant ▁simulation . ▁ ▁How ▁H IL ▁works ▁ ▁A ▁H IL ▁simulation ▁must ▁include ▁elect rical ▁em ulation ▁of ▁sens ors ▁and ▁actu ators . ▁These ▁elect rical ▁em ulations ▁act ▁as ▁the ▁interface ▁between ▁the ▁plant ▁simulation ▁and ▁the ▁embedded ▁system ▁under ▁test . ▁The ▁value ▁of ▁each ▁elect r ically ▁em ulated ▁sensor ▁is ▁controlled ▁by ▁the ▁plant ▁simulation ▁and ▁is ▁read ▁by ▁the ▁embedded ▁system ▁under ▁test ▁( feed back ). ▁Like wise , ▁the ▁embedded ▁system ▁under ▁test ▁implements ▁its ▁control ▁algorithms ▁by ▁output ting ▁actu ator ▁control ▁signals . ▁Ch anges ▁in ▁the ▁control ▁signals ▁result ▁in ▁changes ▁to ▁variable ▁values ▁in ▁the ▁plant ▁simulation . ▁ ▁For ▁example , ▁a ▁H IL ▁simulation ▁platform ▁for ▁the ▁development ▁of ▁autom ot ive ▁anti - lock ▁bra king ▁systems ▁may ▁have ▁mathematical ▁representations ▁for ▁each ▁of ▁the ▁following ▁sub system s ▁in ▁the ▁plant ▁simulation : ▁ ▁Ve h icle ▁dynamics , ▁such ▁as ▁susp ension , ▁whe els , ▁t ires , ▁roll , ▁pitch ▁and ▁y aw ; ▁ ▁Dynam ics ▁of ▁the ▁bra ke ▁system ’ s ▁hyd