Uniform Scaling of Haptic Forces in Surgical Systems

This patent describes a surgical system that uses a single scaling factor to adjust the strength of touch feedback from multiple motors, ensuring the feedback feels consistent even when one motor reaches its maximum power.

What it covers

The patent describes a surgical system comprising an input device, like a master controller, and at least two haptic actuators that provide touch feedback to the user. A controller receives input and determines desired haptic feedback forces for both actuators. If the desired force for the first actuator would exceed its maximum power limit (its "upper output limit" as per claim 1), the controller applies a "common scaling factor" to *both* the desired force for the first actuator and the desired force for the second actuator. This common scaling factor proportionally reduces both forces, ensuring the first actuator operates within its limits while maintaining the relative feel between the two. For example, if a surgeon is pushing against a virtual tissue boundary and the haptic motor for one direction is maxing out, the system scales down all related feedback forces so the surgeon still feels the overall resistance and relative forces, just at a slightly reduced intensity.

What it doesn't cover

• —Haptic feedback systems that are not part of a surgical system, as the claims specifically define a "surgical system."
• —Systems where each haptic actuator's output is scaled independently, rather than using a "common scaling factor" applied to multiple actuators.
• —Haptic feedback where the scaling only occurs when a lower output limit is exceeded, without considering an upper output limit as the primary trigger for scaling.
• —Systems where the scaling factor is *not* removed when the commanded force falls within the actuator's working range, as specified in claim 9.

The clever bit

The novelty lies in applying a *single, common scaling factor* to *multiple* haptic actuators when *any one* of them is about to exceed its operational limits. This ensures that the relative forces and the overall "feel" of the haptic feedback remain proportional and consistent, rather than having one axis of feedback clip or distort independently.

Why it matters

In robotic surgery, haptic feedback is crucial for surgeons to "feel" tissues, sutures, and instrument interactions, improving precision and safety. This patent aims to ensure that this critical feedback remains consistent and proportional, even when individual motors are pushed to their limits. This consistency helps surgeons maintain their sense of control and prevents sudden, unnatural changes in perceived force, which could be distracting or detrimental during delicate procedures.

Real-world examples

• 1.Intuitive Surgical da Vinci surgical systems
• 2.Robotic surgery platforms with haptic feedback
• 3.Surgical training simulators with force feedback