Soft Body Robot Joint Control via Pressure Sensing
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Solution Overview
Problem
Existing humanoid and robots struggle to ensure safe and compliant interactions with humans, particularly children, due to limitations in their ability to absorb impacts and sense contact forces effectively, leading to potential injuries and damage during physical interactions.
Innovation Solution
A robot design featuring soft and deformable body parts filled with fluid, connected to pressure sensors, which change their operational state in response to contact forces to reduce impact and provide safety, combining passive and active compliance for enhanced safety during human interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If humanoid robots use torque-controlled joints for movement control, then the robot can achieve precise positioning and motion control, but the robot cannot ensure safe interactions with humans during physical contact
Solution Approach 1:
The patent applies flexible soft body parts covering the robot's rigid structure and joints. These soft body parts deform under contact force, providing passive compliance that inherently protects humans during physical interaction. The soft body parts act as a first line of defense, reducing impact forces before they reach the torque-controlled joints.
Solution Approach 2:
The patent implements pressure sensors within the soft body parts that detect contact forces in real-time. This feedback is transmitted to the controller, which then adjusts the torque-controlled joints to provide active compliance. The controller modifies joint behavior based on sensed pressure, enabling the robot to respond dynamically to human contact and ensure safety.
2Reliability
If the robot uses soft and deformable body parts to absorb impacts, then the robot can safely interact with humans, but the robot loses structural rigidity and precision
Solution Approach 1:
The patent divides the robot's body into segmented modules, each with its own soft body part and pressure sensor. This segmentation allows different regions to have different compliance characteristics. Critical structural areas maintain more rigidity while interaction areas use softer materials, enabling the robot to balance strength and safety through modular design.
Solution Approach 2:
The patent uses composite construction combining rigid internal structures with flexible external soft body parts. The rigid framework provides structural strength and precision, while the flexible outer layer provides safety during contact. This composite approach allows the robot to maintain both rigidity for precision tasks and compliance for safe human interaction.
3Measurement precision
If the robot uses pressure sensors in soft body parts to sense contact forces, then the robot can detect human contact accurately, but the device complexity increases
Solution Approach 1:
The patent integrates pressure sensors directly into the soft body parts themselves, merging the sensing function with the protective covering. This integration eliminates the need for separate sensor assemblies and reduces overall system complexity. The soft body parts serve dual purposes: providing passive compliance and housing contact force sensors.
Solution Approach 2:
The soft body parts serve multiple functions simultaneously: they provide passive compliance for safety, house pressure sensors for contact detection, and protect underlying rigid structures. This multi-functionality reduces the need for separate components, thereby reducing overall device complexity while maintaining high measurement precision.
4Reliability
If the robot controller modifies joint operations based on pressure changes, then the robot can provide active compliance for safety, but the control system complexity increases
Solution Approach 1:
The controller is pre-programmed with compliance algorithms that automatically activate when pressure sensors detect contact. Instead of requiring complex real-time decision-making, the system has pre-established response protocols that simplify the control logic. The controller modifies joint operations based on predetermined rules triggered by pressure threshold detections.
Solution Approach 2:
The control system uses simple feedback loops where pressure sensor readings directly influence joint torque adjustments. The controller continuously monitors pressure changes and modifies joint operations in response, creating a straightforward feedback mechanism that provides active compliance without requiring complex control algorithms.
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
The robot effectively absorbs impacts and senses contact forces, ensuring safer interactions by modifying its joint operations based on pressure changes, thereby reducing the risk of injury to both humans and robots during physical interactions.
Implementation Method 1
a body segment coupled to a rigid support element. The body segment includes an outer sidewall that is flexible and that encloses an interior space filled with a gas or liquid
Implementation Method 2
The interior space has a first volume prior to contact and a second volume less than the first volume when a contact force is applied to the outer sidewall
Implementation Method 3
Each body part was connected to a pressure sensor to sense contact
Data Source
AI summary
A robot designed for reducing collision impacts during human interaction. The robot includes a robot controller including a joint control module. The robot includes a link including a rigid support element and a soft body segment coupled to the rigid support element, and the body segment includes a deformable outer sidewall enclosing an interior space. The robot includes a pressure sensor sensing pressure in the interior space of the link. A joint is coupled to the rigid support element to rotate or position the link. During operations, the robot controller operates the joint based on the pressure sensed by the pressure sensor. The robot controller modifies operation of the joint from a first operating state with a servo moving or positioning the joint to a second operating state with the servo operating to allow the joint to be moved or positioned in response to outside forces applied to the link.