How a Robot Actuator Controls Force and Speed with Gears

This patent describes a compact robot actuator that uses a special gear system and two motors with different electrical resistance to precisely control both the force and speed applied to a robotic arm or tool.

What it covers

The patent details a "mechanical differential actuator" (Claim 1) designed for interacting with a "mechanical load." It uses a "mechanical differential" (like a special gearbox) with three connection points, called "interaction ports." A "first transducer" (like a motor or brake) with "low impedance" connects to one port, mainly controlling force (Claim 4). A "second transducer" (like another motor) with "high impedance" connects to a second port, mainly controlling speed (Claim 10). The third port connects to the "load," which is what the robot needs to move or apply force to. The clever part is that the second transducer's high impedance is so large that it "does not influence significantly" the overall behavior of the actuator (Claim 1), allowing for independent and precise control of both force and speed at the load. For example, a robot arm could use this to gently pick up a delicate object while also moving it quickly and precisely.

What it doesn't cover

• —Does not cover actuators that lack a mechanical differential with three distinct interaction ports.
• —Does not cover systems where the second transducer's impedance significantly affects the overall equivalent impedance of the actuator (Claim 1).
• —Does not cover actuators where the first transducer is not primarily a source of force or the second transducer is not primarily a source of speed, as described (Claims 4, 10).
• —Does not cover purely electronic or hydraulic control systems that do not incorporate a mechanical differential.
• —Does not cover actuators that cannot control both force and speed at the load.
• —Does not cover systems where the mechanical differential is not compact or cannot transfer large forces relative to its volume.

The clever bit

The novelty lies in combining a mechanical differential with two transducers having vastly different impedances. Specifically, the second transducer's high impedance is engineered to be so large that it isolates the overall actuator's behavior from its own, allowing for independent and precise control of both force and speed at the output load, all within a compact design.

Why it matters

This technology is important for creating more advanced and versatile robots. By allowing precise control over both force and speed in a compact design, it enables robots to perform delicate tasks, interact safely with humans, and operate efficiently in tight spaces. This is crucial for applications ranging from manufacturing to medical robotics.

Real-world examples

• 1.Collaborative robot arms (cobots)
• 2.Surgical robots
• 3.Haptic feedback devices
• 4.Industrial automation manipulators
• 5.Exoskeletons for assistance or rehabilitation