Abstract: A quiet retraction method for regulating constant velocity while parking an arm within a disk drive is described. The method comprises the steps of: driving a motor for the arm using a first drive current for a first period; floating the motor; sampling a back electromotive force (bemf) for a first sampled voltage, while floating the motor; driving the motor with a second drive current during a second period in response to sampling the bemf; determining whether the second drive current exceeds a current limit; estimating the bemf using the first sampled voltage when the second drive current exceeds the current limit; driving the motor with a third current during a third period in response to estimating the bemf; wherein driving the motor with the first, second, and third currents quietly parks the arm, while regulating the constant velocity.

Abstract: A quiet retraction method for regulating constant velocity while parking an arm within a disk drive is described. The method comprises the steps of: driving a motor for the arm using a first drive current for a first period; floating the motor; sampling a back electromotive force (bemf) for a first sampled voltage, while floating the motor; driving the motor with a second drive current during a second period in response to sampling the bemf; determining whether the second drive current exceeds a current limit; estimating the bemf using the first sampled voltage when the second drive current exceeds the current limit; driving the motor with a third current during a third period in response to estimating the bemf; wherein driving the motor with the first, second, and third currents quietly parks the arm, while regulating the constant velocity.

Abstract: Method and apparatus for accelerating a multi-phase motor having a rotatable rotor is disclosed. A first commutation state in which the rotor resides is identified, a first position of the rotor within the first commutation state is determined (preferably within one to two electrical degrees), and a travel distance for the rotor to advance from the first position to a second position is determined. An optimized activation time is next determined for utilizing substantially all available motor torque, and a first drive pulse is applied for the activation time to advance the rotor to the second position. The process is repeated until an intermediate velocity is reached, after which back electromotive force (bemf) commutation is used for control of the motor. The apparatus includes a controller programmed with routines that utilize speeds and accelerations of the motor in accordance with basic Newtonian laws to determine optimized activation times.

Abstract: Method and apparatus for accelerating a multi-phase motor having a rotatable rotor is disclosed. A first commutation state in which the rotor resides is identified, a first position of the rotor within the first commutation state is determined (preferably within one to two electrical degrees), and a travel distance for the rotor to advance from the first position to a second position is determined. An optimized activation time is next determined for utilizing substantially all available motor torque, and a first drive pulse is applied for the activation time to advance the rotor to the second position. The process is repeated until an intermediate velocity is reached, after which back electromotive force (bemf) commutation is used for control of the motor. The apparatus includes a controller programmed with routines that utilize speeds and accelerations of the motor in accordance with basic Newtonian laws to determine optimized activation times.

Abstract: A method and apparatus for determining a substantially accurate position of a stopped rotor within a commutation state of a multi-phase motor. Location of a first commutation state in which the stopped rotor resides is determined by activating a rotor position sense routine programmed into a controller of the apparatus. A model is developed for use in determining the substantially accurate position of the rotor within subsequent commutation states based on a change in an inductive rise time response of a winding of the motor to an application of a non-rotational inducing current applied for a set duration. By executing a rotor distance determination routine resident in the controller, the controller determines a rotor rotational travel distance to a commutation point of a second commutation state, based on the response of the winding to the application of the non-rotational inducing current.