Compliant Mechanism for Robotic Actuator Torque Sensing
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Solution Overview
Problem
Conventional robotic actuators face inaccuracies in load sensing due to non-aligned loads, which are not effectively isolated by existing designs, leading to errors in force measurement.
Innovation Solution
A compliant mechanism is integrated into the robotic actuator, allowing flexibility in two rotational and three translational axes, with a non-compliant axis aligned with the load sensing axis, reducing misaligned load effects and improving sensing accuracy by using a support system that restricts movement in non-aligned directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional load sensors are used in robotic actuators, then force measurement is enabled, but measurement precision deteriorates due to non-aligned loads causing errors
Solution Approach 1:
A compliant mechanism is introduced as an intermediary component between the actuator and the load sensor. This compliant mechanism includes flexible elements that allow misaligned loads to be absorbed through deformation, while transmitting only the aligned load components to the sensor, thereby protecting the sensor from harmful non-aligned load effects
Solution Approach 2:
The compliant mechanism changes the mechanical parameters of the load transmission path by introducing controlled flexibility in specific directions. The mechanism is designed with different stiffness characteristics along different axes, allowing it to selectively transmit or isolate load components based on their alignment with the sensing axis
2Measurement precision
If a compliant mechanism is added to isolate non-aligned loads, then measurement precision improves, but device complexity increases
Solution Approach 1:
The compliant mechanism utilizes flexible beams and thin-walled structures that provide the necessary compliance through elastic deformation. These flexible elements are designed with specific geometries that enable them to deflect in controlled ways, absorbing misaligned loads without requiring complex mechanical joints or additional actuation systems
Solution Approach 2:
The compliant mechanism is segmented into multiple flexible elements arranged in specific configurations. Each element handles specific components of the misaligned loads, and the segmentation allows the mechanism to be integrated into the existing actuator structure without requiring complete redesign of the entire system
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 significantly enhances load sensing accuracy by minimizing the impact of non-aligned loads on the load sensor, reducing errors and uncertainty in measured load values, and allowing for precise torque and force measurement.
Implementation Method 1
A compliant mechanism is integrated into the robotic actuator, allowing flexibility in two rotational and three translational axes, with a non-compliant axis aligned with the load sensing axis
Data Source
AI summary
An embodiment includes a robotic system comprising: a shaft coupled to a robotic appendage; a bearing that couples the shaft to a housing; an actuator that includes a motor; a robotic joint to rotate the shaft and linkage via the bearing; a torque sensor to sense torque created when the motor rotates the appendage; and a bracket including: (a) a rod having an exterior wall, (b) first and second voids in the exterior wall; (c) a beam between the first and second voids, and (d) first and second ends; wherein the bracket is a compliant element and couples: (a) to the actuator via the first end, (b) to the housing via the second end, (c) the actuator to the housing.