stably therefore the second step of the logic flow chart is to determine if a predetermined position is reached if it is then step s 3 of the logic flow chart can be carried out if the predetermined position is not reached the step s 2 is to be carried out continuously until the condition of step s 2 is satisfied step s 3 then can be done the predetermined position in step s 2 can be defined by the following two methods the first method is to define an acceleration time of the electric motor 2 when the logic control unit 5 transmits a motion signal of the electric motor 2 to the motion control unit 3 the timer in the logic control unit 5 will start counting when the counted time reaches a given value it means that the predetermined position is reached the second method is to utilize a position detecting unit 8 as shown in fig1 and arrange it in the area in which the elevator car moves at a uniform speed when the position detecting unit 8 works it means that the elevator car moves at a uniform speed at this moment the electric motor 2 should move at a uniform speed therefore when the logic control unit receives the signal from the position detecting unit 8 the predetermined position of the step s 2 of the logic flow chart will be determined to be reached the step s 3 of the logic flow chart is to read the current value of the electric motor in this step the logic control unit 5 will read the current value of the current detecting unit 4 when the.