Robot coaxial joint unit

Robot Coaxial Joint Unit with Interference Isolation via Cross-Roller Bearings and Disc Couplings

This technology is a robot coaxial joint unit that integrates a reducer, joint torque sensor, cross-roller bearing, and disc coupling within a coaxial joint. It precisely measures rotational torque while mechanically isolating and canceling out non-rotational moment loads and assembly stresses.

In conventional robot joints, moment loads from external forces and stresses caused by assembly tolerances are transmitted directly to the joint torque sensor, leading to interference errors that deviate from the actual rotational torque.

This technology proposes a method where the cross-roller bearing supports the moment load of the output frame, and the joint torque sensor is connected to the output frame via a disc coupling to ensure structural flexibility, thereby reducing unnecessary stress. It can be applied to collaborative robots and force-controlled manipulators, providing the reliability to accurately measure only pure rotational torque even in environments subject to external forces.

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Key Features:

• An input unit that receives driving force from the drive section and transmits it to the coaxially arranged reducer and output section.
• An output unit coaxially arranged with the input unit that outputs rotational force to the exterior using the transmitted driving force.
• A joint torque sensor coaxially arranged with the input and output units to detect torque applied to the coaxial joint.
• Cross-roller bearings that support moment loads from external forces, and disc couplings that reduce assembly stress.

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This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of a low-cost robot system based on multi-degree-of-freedom passive gravity compensation.