Actuator system for work machine, construction machine, control device for work machine, control method for work machine, and computer-readable storage medium storing control program for work machine

A construction machine comprising:

• a working device including a boom rotatably coupled to a vehicle body, an arm rotatably coupled to the boom, and an attachment rotatably coupled to the arm;
• an electric actuator including an electric motor rotatable in both directions and a drive shaft driven by the electric motor, the electric actuator being configured to drive any one of the boom, the arm, or the attachment;
• an electromagnetic brake including an excitation coil, the electromagnetic brake being configured to brake the drive shaft when the excitation coil is in a non-excited state and to release the brake on the drive shaft when the excitation coil is in an excited state;
• a position sensor detecting an angular position of the drive shaft;
• and
• a control device controlling energization and de-energization of each of the electric motor and the excitation coil,
• wherein the control device executes:
• a first process of de-energizing each of the electric motor and the excitation coil;
• a second process of obtaining a transition of the angular position of the drive shaft from a time point at which execution of the first process is completed;
• a third process of calculating, based on the obtained transition, a rotation amount and a rotation direction of the drive shaft from an initial position, the initial position being the angular position of the drive shaft at the time point at which the execution of the first process is completed;
• and
• a fourth process of, when the rotation amount of the drive shaft from the initial position becomes equal to or greater than a predetermined value, controlling the energization of the electric motor so as to apply a torque to the drive shaft in a direction opposite to the rotation direction of the drive shaft from the initial position.

A control device for a work machine, the work machine including:

• an electric actuator including an electric motor rotatable in both directions and a drive shaft driven by the electric motor;
• an electromagnetic brake including an excitation coil, the electromagnetic brake being configured to brake the drive shaft when the excitation coil is in a non-excited state and to release the brake on the drive shaft when the excitation coil is in an excited state;
• and
• a position sensor detecting an angular position of the drive shaft,
• wherein the control device controls energization and de-energization of each of the electric motor and the excitation coil, and
• wherein the control device executes:
• a first process of de-energizing each of the electric motor and the excitation coil;
• a second process of obtaining a transition of the angular position of the drive shaft from a time point at which execution of the first process is completed;
• a third process of calculating, based on the obtained transition, a rotation amount and a rotation direction of the drive shaft from an initial position, the initial position being the angular position of the drive shaft at the time point at which the execution of the first process is completed;
• and
• a fourth process of, when the rotation amount of the drive shaft from the initial position becomes equal to or greater than a predetermined value, controlling the energization of the electric motor so as to apply a torque to the drive shaft in a direction opposite to the rotation direction of the drive shaft from the initial position.

A control method for a work machine, the work machine including:

• an electric actuator including an electric motor rotatable in both directions and a drive shaft driven by the electric motor;
• an electromagnetic brake including an excitation coil, the electromagnetic brake being configured to brake the drive shaft when the excitation coil is in a non-excited state and to release the brake on the drive shaft when the excitation coil is in an excited state;
• and
• a position sensor detecting an angular position of the drive shaft,
• wherein a control device that controls energization and de-energization of each of the electric motor and the excitation coil executes:
• a first process of de-energizing each of the electric motor and the excitation coil;
• a second process of obtaining a transition of the angular position of the drive shaft from a time point at which execution of the first process is completed;
• a third process of calculating, based on the obtained transition, a rotation amount and a rotation direction of the drive shaft from an initial position, the initial position being the angular position of the drive shaft at the time point at which the execution of the first process is completed;
• and
• a fourth process of, when the rotation amount of the drive shaft from the initial position becomes equal to or greater than a predetermined value, controlling the energization of the electric motor so as to apply a torque to the drive shaft in a direction opposite to the rotation direction of the drive shaft from the initial position.

A non-transitory computer-readable storage medium storing a control program for a work machine, the work machine including:

• an electric actuator including an electric motor rotatable in both directions and a drive shaft driven by the electric motor;
• an electromagnetic brake including an excitation coil, the electromagnetic brake being configured to brake the drive shaft when the excitation coil is in a non-excited state and to release the brake on the drive shaft when the excitation coil is in an excited state;
• and
• a position sensor detecting an angular position of the drive shaft,
• wherein the control program causes a control device that controls energization and de-energization of each of the electric motor and the excitation coil to execute:
• a first process of de-energizing each of the electric motor and the excitation coil;
• a second process of obtaining a transition of the angular position of the drive shaft from a time point at which execution of the first process is completed;
• a third process of calculating, based on the obtained transition, a rotation amount and a rotation direction of the drive shaft from an initial position, the initial position being the angular position of the drive shaft at the time point at which the execution of the first process is completed;
• and
• a fourth process of, when the rotation amount of the drive shaft from the initial position becomes equal to or greater than a predetermined value, controlling the energization of the electric motor so as to apply a torque to the drive shaft in a direction opposite to the rotation direction of the drive shaft from the initial position.