Piezoelectric drive device, driving method thereof, robot, and driving method thereof

A robot, comprising:

• a plurality of links;
• a joint which is connected to the plurality of links;
• and
• a piezoelectric drive device which rotates the plurality of links at the joint, the piezoelectric drive device including:
• a piezoelectric drive member which includes a piezoelectric material and a contact projection that contacts a driven body at a contact position;
• and
• a drive circuit which is configured to drive the piezoelectric drive member,
• wherein the drive circuit is configured to drive the piezoelectric drive member with an output torque from allowable maximum output torque Tlim or less within an allowable output torque range so that the drive circuit is configured to set the output torque of the piezoelectric drive member within the allowable output torque range, and
• the allowable maximum output torque Tlim is:
• Tlim=r1×μk×Ns×fs
• wherein r1 is a distance between a rotation center of the driven body and the contact position, μk is a dynamic friction coefficient between the driven body and the contact projection, Ns is a pressing force by which the contact projection presses the driven body when an operation of the piezoelectric drive member stops, and fs is a coefficient of 1 or less.

A driving method of a robot, the robot including:

• a plurality of links;
• a joint which is connected to the plurality of links;
• a piezoelectric drive device which rotates the plurality of links, the piezoelectric drive device including:
• a piezoelectric drive member which includes a piezoelectric material and a contact projection that contacts a driven body at a contact position;
• and
• a drive circuit which is configured to drive the piezoelectric drive member,
• wherein the drive circuit is configured to drive the piezoelectric drive member with an output torque from allowable maximum output torque Tlim or less within an allowable output torque range so that the drive circuit is configured to set the output torque of the piezoelectric drive member within the allowable output torque range, and
• the allowable maximum output torque Tlim is:
• Tlim=r1×μk×Ns×fs
• wherein r1 is a distance between a rotation center of the driven body and the contact position, μk is a dynamic friction coefficient between the driven body and the contact projection, Ns is a pressing force by which the contact projection presses the driven body when an operation of the plurality of piezoelectric drive member stops, and fs is a coefficient of 1 or less,
• the driving method comprising:
• rotating the plurality of links at the joint by driving the piezoelectric drive device;
• and
• setting the output torque of the piezoelectric drive member is equal to or less than the allowable maximum output torque Tlim.

A driving method of a piezoelectric drive device, the piezoelectric drive device including:

• a piezoelectric drive member which includes a piezoelectric material and a contact projection that contacts a driven body at a contact position;
• and
• a drive circuit which is configured to drive the piezoelectric drive member,
• wherein the drive circuit is configured to drive the piezoelectric drive member with an output torque from allowable maximum output torque Tlim or less within an allowable output torque range so that the drive circuit is configured to set the output torque of the piezoelectric drive member within the allowable output torque range, and
• the allowable maximum output torque Tlim is:
• Tlim=r1×μk×Ns×fs
• wherein r1 is a distance between a rotation center of the driven body and the contact position, μk is a dynamic friction coefficient between the driven body and the contact projection, Ns is a pressing force by which the contact projection presses the driven body when an operation of the plurality of piezoelectric drive member stops, and fs is a coefficient of 1 or less,
• the method comprising:
• setting the output torque of the piezoelectric drive member is equal to or less than the allowable maximum output torque Tlim.