Torque compensation

Patent metadata

Field	Value
Publication number	US-9675354-B2
Application number	US-201414154075-A
Country	US
Kind code	B2
Filing date	Jan 13, 2014
Priority date	Jan 14, 2013
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

Embodiments of a clamping system are disclosed. In some embodiments, a system used with a motor assembly and a clamping device is presented, the system adjusting torque limits in the motor assembly according to conditions, for example operating temperature of the motor assembly and aging of the clamping device and the motor assembly. The clamping device can be, for example, a stapler or a vessel sealer.

First claim

What is claimed is:

1. A method of operating a clamping instrument, comprising: obtaining, by control electronics, an initial torque limit for the clamping instrument; adjusting, by the control electronics, the initial torque limit based on a lifetime of a motor assembly of a system operates the clamping instrument, a lifetime of the clamping instrument, or both the lifetime of the motor assembly and the lifetime of the clamping instrument to obtain an adjusted torque limit, clamping the clamping instrument according to the adjusted torque limit.

2. The method of claim 1 , wherein obtaining the initial torque limit includes reading the initial torque limit from the clamping instrument.

3. The method of claim 1 , wherein adjusting the initial torque limit to obtain the adjusted torque limit is further based on one or more of a temperature of the motor assembly and a wrist angle of the clamping instrument.

4. The method of claim 3 , wherein adjusting the initial torque limit is accomplished according to
τ com =τ des *W (θ)*[1−α*( T−T ref )]*[1−β*( L MP )]*[1−γ*( L ins )]+δ*( T−T ref )+ε

where τ com is the adjusted torque limit, T des is desired torque limit, θ is the wrist angle, W(θ) is a scaling adjustment for the wrist angle, T is the temperature of the motor assembly, L MP is the lifetime of the motor assembly, L ins is the lifetime of the clamping instrument, T ref is a reference temperature, and α, β, γ, δ, and ε are coefficients.

5. The method of claim 4 , wherein the clamping instrument is a stapler and the desired torque limit τ des is a calibrated torque limit for the clamping instrument adjusted according to an adjustment for a staple cartridge.

6. The method of claim 4 , wherein W(θ) is given by

W
⁡

(
θ
)

=

1

1
-

ξ
⁡

(

1
-

cos
⁡

(
θ
)

)

where ξ is a coefficient.

7. The method of claim 3 , wherein clamping the clamping instrument according to the adjusted torque limit includes:
calculating a current limit for a clamping motor; and
driving the clamping motor to a clamping position while limiting current to the current limit.

8. The method of claim 7 , wherein calculating the current limit is provided by

I
limit

=

I
NL

+

τ
com

K
T

where I limit is the current limit, I NL is a no load current for the clamping motor, τ com is the adjusted torque limit, and K T is a current to torque conversion parameter for the clamping motor.

9. The method of claim 8 , wherein I NL and K T are adjusted for temperature, and I NL is further adjusted for the lifetime of the motor assembly.

10. The method of claim 8 , wherein I NL is determined based on motor speed and direction.

11. The method of claim 7 , further including:
firing the clamping instrument;
updating the lifetime of the motor assembly to an updated lifetime of the motor assembly and the lifetime of the clamping instrument to an updated lifetime of the clamping instrument; and
storing the updated lifetime of the motor assembly and the updated lifetime of the clamping instrument.

12. The method of claim 1 , further including reading the lifetime of the motor assembly and the lifetime of the clamping instrument and wherein adjusting the initial torque limit to obtain the adjusted torque limit includes scaling the initial torque limit by one or more of a function of the lifetime of a motor assembly and a function of the lifetime of the clamping instrument.

13. The method of claim 1 , further including reading the lifetime of the motor assembly and the lifetime of the clamping instrument, wherein adjusting the initial torque limit to obtain the adjusted torque limit includes adding to the initial torque limit one or more of a function of the lifetime of the motor assembly and a function of the lifetime of the clamping instrument.

14. The method of claim 1 , further including:
driving the clamping instrument through a preset range of motions;
monitoring the clamping instrument during the driving; and
adjusting the initial torque limit to obtain the adjusted torque limit further based on the monitoring.

15. A system that operates a clamping device, comprising:
a processor coupled to receive data from and control motors in a motor assembly coupled to the clamping device, the processor being configured to execute instructions for
acquiring an initial torque limit for the clamping device;
adjusting the initial torque limit based on a lifetime of the motor assembly, a lifetime of the clamping device, or both the lifetime of the motor assembly and the lifetime of the clamping device to obtain an adjusted torque limit; and
clamping the clamping device according to the adjusted torque limit.

16. The system of claim 15 , wherein acquiring the initial torque limit includes reading the initial torque limit from the clamping device.

17. The system of claim 15 wherein adjusting the initial torque limit to obtain the adjusted torque limit is further based on one or more of a temperature of the motor assembly and a wrist angle of the clamping device.

18. The system of claim 17 , wherein adjusting the initial torque limit is accomplished according to
τ com =τ des *W (θ)*[1−α*( T−T ref )]*[1−β*( L MP )]*[1−γ*( L ins )]+δ*( T−T ref )+ε

where τ com is the adjusted torque limit, τ des is desired torque limit, θ is the wrist angle, W(θ) is a scaling adjustment for the wrist angle, T is the temperature of the motor assembly, L MP is the lifetime of the motor assembly, L ins is the lifetime of the clamping device, T ref is a reference temperature, and α, β, γ, δ, and ε are coefficients.

19. The system of claim 18 , wherein the clamping device is a stapler and the desired torque limit τ des is a calibrated torque limit for the clamping device adjusted according to an adjustment for a staple cartridge.

20. The system of claim 18 , wherein W(θ) is given by

W
⁡

(
θ
)

=

Assignees

• Intuitive Surgical Operations

Inventors

• Weir David W
• Wu Melody
• Brisson Gabriel F
• Durant Kevin
• Duque Grant

Classifications

• A61B1/000095

  for image enhancement · CPC title

• A61B17/08

  Wound clamps {or clips, i.e. not or only partly penetrating the tissue (suture bridges A61B17/0466); Devices for bringing together the edges of a wound} · CPC title

• A61B17/07207 Primary

  the staples being applied sequentially · CPC title

• A61B2090/031

  torque limiting · CPC title

• A61B2017/00398

  using powered actuators, e.g. stepper motors, solenoids · CPC title