A variable stiffness structure configured to isolate a mass from unwanted vibrations includes a negative stiffness element and an actuator operatively coupled to the negative stiffness element. The actuator is configured to be actuated to control a stiffness of the negative stiffness element. The variable stiffness structure may also include a positive stiffness element coupled to the negative stiffness element.

A test stand for an unmanned aerial vehicle comprising: a base arranged to make contact with the ground; a frame extending from the base, the frame comprising at least a first side portion and a second side portion that define a space therebetween; and a mount slidably attached to the frame within the space, the mount configured to affix to an unmanned aerial vehicle such that the mount and the unmanned aerial vehicle slide within the defined space in a direction parallel to the frame during a test flight.

A test stand for an unmanned aerial vehicle comprising: a base arranged to make contact with the ground; a frame extending from the base, the frame comprising at least a first side portion and a second side portion that define a space therebetween; and a mount slidably attached to the frame within the space, the mount configured to affix to an unmanned aerial vehicle such that the mount and the unmanned aerial vehicle slide within the defined space in a direction parallel to the frame during a test flight.

Cushions include a chassis core having a rigid or semi-rigid base sheet; and a plurality of paired flat springs coupled to the rigid or semi-rigid base sheet, wherein each paired flat spring comprises a lower flat spring including a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, and an upper flat spring including a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, wherein the first and second terminal ends of the upper flat spring are fixedly attached to respective first and second terminal ends of the lower flat spring such that the upper flat spring is inverted relative to the lower flat spring. Also disclosed are processes for manufacturing the core chassis.

Cushions include a chassis core having a rigid or semi-rigid base sheet; and a plurality of paired flat springs coupled to the rigid or semi-rigid base sheet, wherein each paired flat spring comprises a lower flat spring including a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, and an upper flat spring including a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, wherein the first and second terminal ends of the upper flat spring are fixedly attached to respective first and second terminal ends of the lower flat spring such that the upper flat spring is inverted relative to the lower flat spring. Also disclosed are processes for manufacturing the core chassis.

Cushions include a chassis core. having a rigid or semi-rigid base sheet; and a plurality of paired flat springs coupled to the rigid or semi-rigid base sheet, wherein each paired flat spring comprises a lower flat spring including a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, and an upper flat spring including a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, wherein the first and second terminal ends of the upper flat spring are fixedly attached to respective first and second terminal ends of the lower flat spring such that the upper flat spring is inverted relative to the lower flat spring. Also disclosed are processes for manufacturing the core chassis.

Cushions include a chassis core. having a rigid or semi-rigid base sheet; and a plurality of paired flat springs coupled to the rigid or semi-rigid base sheet, wherein each paired flat spring comprises a lower flat spring including a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, and an upper flat spring including a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, wherein the first and second terminal ends of the upper flat spring are fixedly attached to respective first and second terminal ends of the lower flat spring such that the upper flat spring is inverted relative to the lower flat spring. Also disclosed are processes for manufacturing the core chassis.

A magnetic spring assembly that uses the bistable magnetic nature of permanent magnets mediated by a spring material to allow one or more attached vibrating masses to take on the damping characteristics of the magnetic spring assembly includes a permanent magnet body with an attach point 15 for a first vibrating mass, two spring materials, and two magnetic disks firmly attached to a shaft having an attach point 23 for a second vibrating mass to manufacture a mass damper 20 for damping vibrations on at least one of the attached masses. The spring materials can be an elastic material or a spring that is placed between the magnetic disks and the magnetic body to allow the magnetic disks to vibrate in a spring like manner. Passive tuning of the damping characteristics of the magnetic spring assembly is achievable through selected force tuning between the magnetic force from the permanent magnet and the compression force of the spring materials, and active tuning of the magnetic spring assembly is achievable by adding control coils in the magnet body to alter the magnetic force or having spring materials with characteristics that are electrically control to alter the compression force.

The present disclosure discloses an actuator, comprising a first torsion spring body and a second torsion spring body, each of the first torsion spring body and the second torsion spring body comprising: an inner ring; an outer ring; and a plurality of elastic units, connected in parallel between the inner ring and the outer ring. An outer ring of the first torsion spring body and an outer ring of the second torsion spring body are rigidly connected, and an inner ring of the first torsion spring body and an inner ring of the second torsion spring body are aligned with each other. The actuator further includes a motor element and a braking element. The motor element is for providing an output torque, and is connected with the inner ring of the first torsion spring body. The braking element is for providing a braking torque, and is connected with the inner ring of the second torsion spring body.

The present disclosure discloses an actuator, comprising a first torsion spring body and a second torsion spring body, each of the first torsion spring body and the second torsion spring body comprising: an inner ring; an outer ring; and a plurality of elastic units, connected in parallel between the inner ring and the outer ring. An outer ring of the first torsion spring body and an outer ring of the second torsion spring body are rigidly connected, and an inner ring of the first torsion spring body and an inner ring of the second torsion spring body are aligned with each other. The actuator further includes a motor element and a braking element. The motor element is for providing an output torque, and is connected with the inner ring of the first torsion spring body. The braking element is for providing a braking torque, and is connected with the inner ring of the second torsion spring body.