A monitoring device includes: an acquisition unit for acquiring a clock signal output from a communication circuit that outputs the clock signal; and a monitoring unit for analyzing the waveform of the clock signal acquired by the acquisition unit, based on a predetermined reference clock signal having a period equal to or shorter than a period of the clock signal to thereby determine whether or not there is a sign of malfunction in the communication circuit.

A method of operating a power tool having a motor and a controller is provided. The method includes: receiving a position of a variable-speed input mechanism mounted on the power tool; determining a target speed of the motor corresponding to the position of the variable-speed input mechanism; determining an underspeed threshold corresponding to the target speed; determining a rotational speed of the motor; and interrupting a supply of power to the motor if the rotational speed of the motor is less than the underspeed threshold.

A method of operating a power tool having a motor and a controller is provided. The method includes: receiving a position of a variable-speed input mechanism mounted on the power tool; determining a target speed of the motor corresponding to the position of the variable-speed input mechanism; determining an underspeed threshold corresponding to the target speed; determining a rotational speed of the motor; and interrupting a supply of power to the motor if the rotational speed of the motor is less than the underspeed threshold.

A hand-held power tool is provided that includes a housing assembly, an output spindle, and a motor endbell. The housing assembly supports an electric motor having a rotor configured to rotate when the electric motor is supplied with power. The output spindle protrudes from an output end of the housing assembly, and is functionally coupled to the rotor such that the output spindle rotates in response to a rotation of the rotor. The motor endbell is located on the housing assembly adjacent the electric motor and opposite the output spindle. An illustrative controller is operable to determine phases of a fastening operation in which the hand-held power tool is operating. The phases of the fastening operation of the hand-held power tool include two phases including: (1) a continuous run phase and (2) an impacting phase.

A drive device for an electric motor according to the present invention includes a first relay that turns a power supply line on and off leading from a power supply to an electric motor, a resistor provided on a bypass line that bypasses the first relay, a second relay that turns the bypass line on and off, a relay control circuit that outputs a relay control signal common to the first relay and the second relay, and a delay unit that delays the turn-on timing based on the relay control signal of the first relay later than the turn-on timing based on the relay control signal of the second relay. This configuration makes it possible to add a function for suppressing an inrush current without increasing the number of output connectors of a relay control circuit.

A drive device for an electric motor according to the present invention includes a first relay that turns a power supply line on and off leading from a power supply to an electric motor, a resistor provided on a bypass line that bypasses the first relay, a second relay that turns the bypass line on and off, a relay control circuit that outputs a relay control signal common to the first relay and the second relay, and a delay unit that delays the turn-on timing based on the relay control signal of the first relay later than the turn-on timing based on the relay control signal of the second relay. This configuration makes it possible to add a function for suppressing an inrush current without increasing the number of output connectors of a relay control circuit.

A non-sensor type closed-loop stabilization control algorithm comprises the following steps: 1, reading all voltages V.sub.k−1 and currents I.sub.k−1 for driving a multi-axis stabilization motor; 2, calculating and outputting all coil resistances R.sub.k−1 in the multi-axis stabilization motor; 3, reading all the coil resistances, voltages and currents in the steps 1 and 2, and calculating and outputting counter electromotive force E.sub.k−1 of all the coils in the multi-axis stabilization motor; 4, reading an stabilization compensation angle θ.sub.k, each coil resistance and the counter electromotive force, and calculating and outputting a closed-loop stabilization control F.sub.k; and 5, then waiting for a time step k=k+1, and repeating the steps in the steps 1 to 4. It aims to add a closed-loop control element to a motor without a sensor to achieve an excellent stabilization effect and to reduce the risk of image blurring caused by resonance.

The invention relates to a method for checking an electrical value of an electric machine, in particular an electric machine of a coordinate measuring device. The electric machine has an electric drive comprising a stator and a rotor. The method includes the steps of: detecting a value of a drive current delivered to the electric drive for driving the rotor, detecting a measured value of an electrical input variable of the electric machine, determining a calculated value of the electrical input variable on the basis of the detected value of the drive current and on the basis of a performance model of the electric machine, and determining a comparison value on the basis of the detected measured value and the calculated value of the electrical input variable, in order to check the detected value of the drive current.

A blower motor control device stops energization to a motor when a rotation speed of a rotor reaches a learn rotation speed, and acquires a correction amount as a new learn value for correcting a position error of the rotor relative to a Hall element by using an induced voltage in a coil of the motor and a detection signal from a rotation sensor. The blower motor control device stores the new learn value in a ROM. The blower motor control device corrects the position error by using a previous learn value read from the ROM, for energization control of the motor, until the rotation speed reaches the learn rotation speed.

A motor drive signal generator configured to combine at least a part of a first input waveform with at least a part of a second input waveform to create a compound waveform, wherein the first waveform is a sine wave and the second input waveform is a square wave.