Abstract: A construction machine includes an attitude sensor that detects the current attitude of an upper turning body; a reference angular acceleration calculation unit that calculates a reference angular acceleration to be generated when an electric turning motor is driven by a torque command value generated according to the operation amount of an operation part; a reference gravity torque calculation unit that, on the basis of the current attitude and the deviation between an actual angular acceleration, calculates a reference gravity torque; a gravity compensation torque calculation unit that calculates a gravity compensation torque for compensating a torque component generated about the turning axis by the gravity in the current attitude; and a correction unit that corrects the torque command value by using the gravity compensation torque so as to cancel the torque component generated about the turning axis by the gravity in the current attitude.

Abstract: An optical transmitter includes a bias supplying unit configured to supply a first bias voltage, a second bias voltage and a third bias voltage to an optical modulator. The bias supplying unit acquires a first voltage value at which an average value of an optical output signal becomes maximum by sweeping the first bias voltage, acquires a second voltage value at which an average value of the optical output signal becomes maximum by sweeping the second bias voltage, and acquires a third voltage value at which an average value of the optical output signal becomes maximum by sweeping the third bias voltage. The bias supplying unit determines a value of the first bias voltage based on the first voltage value, determines a value of the second bias voltage based on the second voltage value, and determines a value of the third bias voltage based on the third voltage value.

Abstract: An optical transmitter includes a bias supplying unit configured to supply a first bias voltage, a second bias voltage and a third bias voltage to an optical modulator. The bias supplying unit acquires a first voltage value at which an average value of an optical output signal becomes maximum by sweeping the first bias voltage, acquires a second voltage value at which an average value of the optical output signal becomes maximum by sweeping the second bias voltage, and acquires a third voltage value at which an average value of the optical output signal becomes maximum by sweeping the third bias voltage. The bias supplying unit determines a value of the first bias voltage based on the first voltage value, determines a value of the second bias voltage based on the second voltage value, and determines a value of the third bias voltage based on the third voltage value.

Abstract: A control method for an engine includes determining whether a predetermined fuel supply stop condition has been fulfilled, executing stop time vibration suppression control of, after stop of fuel supply in response to fulfillment of the predetermined fuel supply stop condition, temporarily performing fuel supply to the engine to suppress vehicle vibration, and stopping fuel supply to all cylinders after the execution of the stop time vibration suppression control. The stop time vibration suppression control includes determining whether a first predetermined number of cylinders have undergone a combustion stroke after the stop of the fuel supply, the first predetermined number being according to a engine revolution speed or a reduction ratio from the engine to drive wheels, and in a case where the first predetermined number of cylinders have undergone the combustion stroke, performing fuel supply to a second predetermined number of cylinders.

Abstract: A control method for an engine includes determining whether a predetermined fuel supply stop condition has been fulfilled, executing stop time vibration suppression control of, after stop of fuel supply in response to fulfillment of the predetermined fuel supply stop condition, temporarily performing fuel supply to the engine to suppress vehicle vibration, and stopping fuel supply to all cylinders after the execution of the stop time vibration suppression control. The stop time vibration suppression control includes determining whether a first predetermined number of cylinders have undergone a combustion stroke after the stop of the fuel supply, the first predetermined number being according to an engine revolution speed or a reduction ratio from the engine to drive wheels, and in a case where the first predetermined number of cylinders have undergone the combustion stroke, performing fuel supply to a second predetermined number of cylinders.

Abstract: An optical transmitter including a signal processor, a driver, a current detector, an amplitude detector, and a controller is disclosed. The signal processor outputs a modulation signal that has first amplitude. The driver amplifies the modulation signal for generating a driving signal that has second amplitude. The current detector detects a supply current that the driver consumes for the amplification. The amplitude detector detects the second amplitude of the driving signal. The controller keeps the driver based at least in part on the supply current detected by the current detector for maintaining the supply current of the driver in a first target value. The controller varies the first amplitude of the modulation signal based at least in part on the second amplitude of the driving signal detected by the amplitude detector for maintaining the second amplitude of the driving signal in a second target value.

Abstract: An optical transmitter including a signal processor, a driver, a current detector, an amplitude detector, and a controller is disclosed. The signal processor outputs a modulation signal that has first amplitude. The driver amplifies the modulation signal for generating a driving signal that has second amplitude. The current detector detects a supply current that the driver consumes for the amplification. The amplitude detector detects the second amplitude of the driving signal. The controller keeps the driver based at least in part on the supply current detected by the current detector for maintaining the supply current of the driver in a first target value. The controller varies the first amplitude of the modulation signal based at least in part on the second amplitude of the driving signal detected by the amplitude detector for maintaining the second amplitude of the driving signal in a second target value.

Abstract: A bias control circuit for an optical modulator including a pair of optical waveguides and a power monitor is disclosed. The bias control circuit includes a bias generator, a differential amplifier, and a controller. The bias generator provides a bias signal to one of the optical waveguides. The bias signal includes a dither signal having a predetermined frequency. The differential amplifier receives a monitor signal from the power monitor and a reference signal, and generates an amplified signal corresponding to a difference between the monitor signal and the reference signal. The controller detects frequency components contained in the amplified signal. The frequency components originates from the dither signal. The controller generates a control signal according to intensity of the frequency components. The bias signal is adjusted according to the control signal provided from the controller.

Abstract: A bias control circuit for an optical modulator including a pair of optical waveguides and a power monitor is disclosed. The bias control circuit includes a bias generator, a differential amplifier, and a controller. The bias generator provides a bias signal to one of the optical waveguides. The bias signal includes a dither signal having a predetermined frequency. The differential amplifier receives a monitor signal from the power monitor and a reference signal, and generates an amplified signal corresponding to a difference between the monitor signal and the reference signal. The controller detects frequency components contained in the amplified signal. The frequency components originates from the dither signal. The controller generates a control signal according to intensity of the frequency components. The bias signal is adjusted according to the control signal provided from the controller.

Abstract: An optical transmitter includes a light source configured to generate direct current light; a multi-value modulator configured to modulate the direct current light; an optical switch configured to block output light of the multi-value modulator; a driving circuit configured to output a driving signal for driving the multi-value modulator; a bias control circuit configured to control a bias voltage applied to the multi-value modulator, according to an optical output power of the multi-value modulator; and a control circuit configured to control operations of the optical switch, the driving circuit and the bias control circuit, wherein the control circuit decreases an amplitude of the driving signal output from the driving circuit while synchronizing with the blocking of the output light of the multi-value modulator by the optical switch.

Abstract: A Mach-Zehnder (MZ) modulator made of semiconductor material and a method to drive the MZ-modulator are disclosed. The MZ-modulator includes a pair of arms to vary the phase of the optical beam propagating therein. One of the arms further provides the phase presetter that varies the phase of the optical beam by ?. The arms are driven by modulation signals complementary to each other but with the DC bias equal to each other.

Abstract: An optical transmitter implemented with two QPSK (Quadrature Phase Shift Keying) modulators is disclosed. Each of the QPSK modulators provides a waveguide made of semiconductor material inducing the QCSE (Quantum Confined Stark Effect) by a bias supplied thereto. The optical performance of one of the QPSK modulators is determined by supplying a deep bias to the other of the QPSK modulator to eliminate the optical output therefrom.

Abstract: An optical transmitter includes a light source configured to generate direct current light; a multi-value modulator configured to modulate the direct current light; an opto-isolator configured to block output light of the multi-value modulator; a driving circuit configured to output a driving signal for driving the multi-value modulator; a bias control circuit configured to control a bias voltage applied to the multi-value modulator, according to an optical output power of the multi-value modulator; and a control circuit configured to control operations of the opto-isolator, the driving circuit and the bias control circuit, wherein the control circuit decreases an amplitude of the driving signal output from the driving circuit while synchronizing with the blocking of the output light of the multi-value modulator by the opto-isolator.