Isolated Force-Torque Sensor Assembly for High-Impact Robot Tools
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Solution Overview
Problem
Force/torque sensors in robotic systems for surgical procedures are often subjected to high impact forces that exceed their operating range, potentially causing damage during high-impact procedures like acetabular cup implantation in total hip arthroplasty, where manual striking is involved.
Innovation Solution
An isolated force/torque sensor assembly is designed with a high force end effector interface mechanically grounded to the robot arm, bypassing the transducer during high-force applications, and a low force end effector interface with a transducer to measure and generate output signals for fine motion control, featuring a plurality of beams that act as stops to prevent overload and maintain signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force/torque sensor is attached between the robot arm and the tool to measure all forces and torques, then measurement completeness is improved, but the sensor is subjected to high impact forces that may exceed its operating range or cause damage
Solution Approach 1:
The end effector is segmented into a high force interface and a low force interface, with the transducer positioned between them. This segmentation allows the high force interface to handle impact loads while the low force interface maintains measurement accuracy for fine motion control, resolving the contradiction between measurement completeness and sensor durability.
Solution Approach 2:
The transducer acts as an intermediary element between the high force interface and the low force interface. It isolates the sensitive measurement components from high impact forces while still enabling accurate measurement of forces applied during fine motion control, thus protecting the sensor from damage while maintaining measurement capability.
2Measurement precision
If the force/torque sensor is directly connected to the tool to capture all forces, then force measurement accuracy is improved, but the sensor becomes vulnerable to overload during high-impact procedures
Solution Approach 1:
The high force interface is designed to absorb and dissipate impact forces before they reach the transducer. This beforehand cushioning protects the sensitive measurement elements from overload during high-impact procedures while maintaining accurate force measurement capability during normal operation.
Solution Approach 2:
Different parts of the end effector have different mechanical properties: the high force interface is designed to withstand large loads, while the low force interface maintains high measurement precision. This local differentiation of mechanical properties allows the system to handle both high-impact and fine-motion control scenarios effectively.
3Adaptability or versatility
If a six component force/torque sensor is used to measure all forces and torques, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The end effector assembly serves multiple functions: the high force interface handles impact loads, the transducer performs measurements, and the low force interface enables fine motion control. This multi-functionality integrates measurement capability and impact resistance into a single unified structure, reducing overall system complexity while maintaining comprehensive measurement capability.
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 configuration effectively isolates the force/torque sensor from high impact forces, preventing damage and ensuring accurate force and torque measurements for precise robotic control during high-impact surgical procedures.
Implementation Method 1
one or more strain gauges are associated with each beam. Each strain gauge generates an electrical signal proportional to a flexure of the beam with which the strain gauge is associated.
Data Source
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AI summary
An isolated force/torque sensor assembly (10, 110, 210) for a force controlled robot (12) includes an end effector (22, 122, 222) for operatively attaching to an arm (14) of the force controlled robot (12), the end effector (22, 122, 222) having a gripping portion (36, 136, 236) adapted to be gripped by a hand of a user, and a force/torque sensor (42, 142, 242) adapted to be disposed between the gripping portion (36, 136, 236) and the arm (14) of the robot (12), the force/torque sensor (42, 142, 242) having a high force end effector interface (44, 144, 244) adapted to be attached to the arm (14) of the robot (12), a low force end effector interface (48, 148, 248) operatively attached to the gripping portion (36, 136, 236), and a transducer (45, 145, 245) disposed between the high force end effector interface (44, 144, 244) and the low force end effector interface (48, 148, 248) for reacting to loads applied to the low force end effector interface (48, 148, 248) for user controlled positioning of a surgical tool and for generating corresponding output signals, and wherein the transducer (45, 145, 245) is bypassed for high loads.