Sensorless Force Control for TEE Probe Actuation
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Solution Overview
Problem
Transesophageal echocardiography (TEE) procedures face challenges such as echocardiographer fatigue, increased x-ray exposure, and communication difficulties due to the need for constant adjustments of the TEE probe, as well as safety concerns with robotic control lacking haptic feedback for force exertion on the esophagus.
Innovation Solution
A robotic actuation system with sensorless force control, using motorized gears and a robotic workstation to generate motor commands for simultaneous position and contact force control of the TEE probe, allowing safe remote manipulation and compatibility with existing probes without the need for force sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual control of TEE probe is used, then echocardiographer can adjust probe position, but echocardiographer experiences fatigue and poor visualization during long procedures
Solution Approach 1:
The patent replaces manual mechanical control with an automated robotic system that uses motorized actuators to control probe positioning. The robotic system eliminates manual fatigue while maintaining precise positioning capability through automated control algorithms that adjust probe position based on imaging feedback.
Solution Approach 2:
The system implements closed-loop feedback control where the robotic system continuously monitors imaging quality and automatically adjusts probe position to optimize visualization. This feedback mechanism ensures consistent image quality without requiring manual intervention, thereby maintaining reliability during long procedures.
2Reliability
If TEE probe length is increased to reach target anatomy, then visualization capability is improved, but x-ray exposure of echocardiographer is maximized
Solution Approach 1:
The robotic system acts as an intermediary between the echocardiographer and the TEE probe. The echocardiographer controls the robotic arm from a remote position outside the x-ray field, while the robotic arm manipulates the probe inside the patient's esophagus. This intermediary arrangement allows the echocardiographer to maintain visualization capability while eliminating direct exposure to x-rays.
Solution Approach 2:
The system replaces direct manual manipulation with robotic automation, allowing the echocardiographer to operate from a protected location. The robotic system transmits control signals rather than physical force, enabling remote operation that reduces radiation exposure while maintaining probe control capability.
3Ease of operation
If robotic actuation is used for TEE probe control, then echocardiographer fatigue is reduced, but safety concerns arise due to lack of haptic feedback for force control
Solution Approach 1:
The robotic system implements sensorless force control using feedback from motor current measurements and kinematic models. The system estimates contact force between the probe and esophageal tissue by monitoring motor currents and comparing them against pre-calibrated force-current relationships. This feedback loop automatically adjusts actuation to maintain safe force levels, compensating for the lack of direct haptic feedback to the operator.
Solution Approach 2:
The robotic system performs self-regulation of contact force through automated control algorithms that monitor motor currents and adjust actuation accordingly. The system serves its own safety function by automatically detecting and correcting excessive force conditions without requiring manual haptic feedback, thereby maintaining tissue safety while reducing operator fatigue.
4Measurement precision
If force sensors are added to TEE probe for contact force measurement, then force control accuracy is improved, but probe complexity and manufacturing difficulty increase
Solution Approach 1:
The system replaces direct mechanical force sensing with an indirect measurement approach using motor current sensors and kinematic modeling. Instead of adding force sensors to the probe, the system uses the existing motor actuators' current measurements combined with calibrated force-current relationships to estimate contact force. This substitution maintains measurement capability while avoiding probe complexity increases.
Solution Approach 2:
The system introduces an intermediary computational model that translates motor current measurements into force estimates. Rather than directly measuring force at the probe tip, the system uses the relationship between motor current and contact force, calibrated through pre-procedure measurements, to infer force levels. This intermediary approach achieves accurate force control without modifying the probe structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system reduces the risk of esophageal injury and enables safe, efficient remote control of TEE probes during procedures, addressing fatigue and communication challenges while maintaining effective visualization and acoustic coupling.
Implementation Method 1
A robotic actuation system with sensorless force control, using motorized gears and a robotic workstation to generate motor commands for simultaneous position and contact force control of the TEE probe
Implementation Method 2
an echocardiographer 13 holds a TEE probe 14, which passes through a mouth of a patient 16 into a esophagus to visualize a heart of patient 16
Data Source
Figure 1~2
Figure 3~4B
Figure 5~6B
AI summary
A robotic actuation system for sensorless force control of an interventional tool (14) having cable driven distal end (e.g., a probe, a steerable catheter, a guidewire and a colonoscope). The system employs a robotic actuator (30)having one or more motorized gears operate the cable drive of the interventional tool (14). The system further employs a robotic workstation (20)to generate motor commands for simultaneous actuation position and contact force control of the interventional tool (14). The motor commands are a function of an actuation position measurement and a motor current measurement of the at least one motorized gear for a desired actuation position of the interventional tool (14).