Torque-Free Robot Arm

Torque-Free Robot Arm Combining a Spring Counterbalancer and a Double Parallelogram

This technology is a torque-free robot arm that mechanically offsets the torque caused by the link's own weight by applying a spring, wire, pulley, and counterbalancer structure to the link joints, and aligns the reference angles of multi-degree-of-freedom links using a double parallelogram unit.

When designing robot arms, the torque generated at the joints due to the arm's own weight necessitates high-performance, expensive motors and reducers, which increases manufacturing costs and limits the general-purpose use of these arms in service robots.

This technology proposes a method that uses a counterbalancer utilizing spring compression and wire tension at each joint to offset self-weight torque, while also compensating for the gravitational torque exerted on lower links by the rotation of upper links through a parallelogram wire structure. Applicable to service and collaborative robots, it enables operation with low-cost, compact motors, thereby accelerating the mass adoption of robot arms.

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Key Features:

• A base and a first link rotatably connected to the base to form a first joint horizontal to the ground
• A first counterbalancer that compensates for the gravity caused by the weight of the first link when it rotates around the first joint
• A structure that mechanically offsets the link's self-weight torque using spring compression and wire tension
• A double parallelogram unit that aligns reference angles when connecting multi-degree-of-freedom links