Cable-driven robot arm with rolling joints

Lightweight Robot Arm Combining Rolling Joints and Cable Drive

This technology proposes a cable routing and pulley-based kinematic mechanism for driving the links of a multi-joint robot arm. By routing cables diagonally through multiple idler pulleys arranged concentrically at each joint, the effective length of the cable remains constant during joint rotation, allowing for independent control (decoupling) of the front and rear link movements without mutual interference.

Conventional multi-joint robots place actuators at each joint, which increases weight and reduces overall efficiency. Furthermore, auxiliary link methods require thicker structures to achieve higher payloads, leading to limited workspaces and collision risks, while belt-drive methods face stiffness limitations during heavy-duty tasks.

This technology centralizes motors in the base link and independently controls the front and rear links through separate cable routing. Specifically, by placing multiple idler pulleys concentric to the joint's center of rotation and routing cables diagonally, the tension length of the link drive cables is maintained even during rolling joint motion, thereby improving control precision and load-handling capacity.

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Key Features:

• A base link unit where the first and second motors for driving each link of the robot arm are co-located
• A front link unit rotatably connected to the joint of the base link unit, and an intermediate link unit rotatably connected to the front link unit
• A front link drive cable unit wound around the first motor and routed through the front link unit to the intermediate link unit to control the rotation of the front link unit
• A rear link drive cable unit wound around the second motor and routed through the front and intermediate link units to the rear link unit to control the rotation of the rear link unit

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