Displacement detecting apparatus, torque detecting apparatus, robot apparatus and displacement detecting method

A torque detecting apparatus which detects a force of deforming an elastic body, by a displacement detecting apparatus, through a quantity of a relative rotational displacement of the elastic body against a fixed member arranged in the vicinity of the elastic body, which is formed by deformation of the elastic body, wherein the displacement detecting apparatus comprises:

• a scale which has an optical pattern of a lattice arrangement;
• a detecting head which has light-receiving elements of a lattice arrangement, which detect the optical pattern of the scale;
• and
• a controlling apparatus which acquires a quantity of a relative rotational displacement of the detecting head with respect to the scale, based on a change of outputs of the light-receiving elements, at the time when the scale and the detecting head are relatively and rotationally displaced, wherein
• the controlling apparatus acquires the quantity of the relative rotational displacement of the detecting head with respect to the scale, by combining a quantity of a rough relative rotational displacement of the detecting head with respect to the scale, which has been acquired from an output of the total of light quantities that are output from each of the light-receiving elements in the detecting head, with a quantity of a fine relative rotational displacement between the scale and the detecting head, which has been acquired from an incremental displacement signal that is output from each of the light-receiving elements in the detecting head, and
• wherein any one of the scale and the detecting head is fixed to the elastic body, the other is fixed to the fixed member so as to face any one of the scale and the detecting head fixed to the elastic body, and the torque detecting apparatus detects a force that is applied to the elastic body through the quantity of the relative rotational displacement between the scale and the detecting head, which the displacement detecting apparatus acquires.

A robot apparatus comprising:

• a robot arm provided with a torque detecting apparatus at a joint or a driving unit of a robot hand;
• a controlling unit configured to execute a robot controlling to control an operation of the robot arm, based on a driving torque of the driving unit detected by the torque detecting apparatus, wherein
• the torque detecting apparatus detects a force of deforming an elastic body, by a displacement detecting apparatus, through a quantity of a relative rotational displacement of the elastic body against a fixed member arranged in the vicinity of the elastic body, which is formed by deformation of the elastic body, wherein the displacement detecting apparatus comprises:
• a scale which has an optical pattern of a lattice arrangement;
• a detecting head which has light-receiving elements of a lattice arrangement, which detect the optical pattern of the scale;
• and
• a controlling apparatus which acquires a quantity of a relative rotational displacement of the detecting head with respect to the scale, based on a change of outputs of the light-receiving elements, at the time when the scale and the detecting head are relatively and rotationally displaced,
• wherein the controlling apparatus acquires the quantity of the relative rotational displacement of the detecting head with respect to the scale, by combining a quantity of a rough relative rotational displacement of the detecting head with respect to the scale, which has been acquired from an output of the total of light quantities that are output from each of the light-receiving elements in the detecting head, with a quantity of a fine relative rotational displacement between the scale and the detecting head, which has been acquired from an incremental displacement signal that is output from each of the light-receiving elements in the detecting head, and wherein any one of the scale and the detecting head is fixed to the elastic body, the other is fixed to the fixed member so as to face any one of the scale and the detecting head fixed to the elastic body, and the torque detecting apparatus detects a force that is applied to the elastic body through the quantity of the relative rotational displacement between the scale and the detecting head, which the displacement detecting apparatus acquires.

A displacement detecting method for acquiring a quantity of a relative rotational displacement, with respect to a scale having an optical pattern of a lattice arrangement, of a detecting head having light-receiving elements of a lattice arrangement, which detect the optical pattern of the scale, based on a change of outputs of the light-receiving elements, at the time when the scale and the detecting head are relatively and rotationally displaced, wherein the method comprises:

• a first acquiring for acquiring a quantity of a rough relative rotational displacement of the detecting head with respect to the scale, which has been acquired from an output of the total of light quantities that are output from each of the light-receiving elements in the detecting head;
• a second acquiring for acquiring a quantity of a fine relative rotational displacement between the scale and the detecting head, which has been acquired from an incremental displacement signal that is output from each of the light-receiving elements in the detecting head;
• a displacement detecting for combining the quantity of the rough relative rotational displacement of the detecting head with respect to the scale acquired in the first acquiring with the quantity of the fine relative rotational displacement between the scale and the detecting head acquired in the second acquiring, to acquire the quantity of the relative rotational displacement of the detecting head with respect to the scale.