Stewart Platform Actuators for High Payload Mobility
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Solution Overview
Problem
Current mobility assistive devices and robotic applications using serial manipulators have limitations such as low payload-to-weight ratio, poor force exertion capabilities, and inaccurate positioning and speed, which hinder their effectiveness in mimicking human or animal locomotion.
Innovation Solution
A motion system utilizing Stewart platform based actuators with a central controller that adjusts the position, orientation, and motion trajectory of multiple actuators in real time, combined with sensors and a damper system for enhanced stiffness control, allowing for precise and accurate movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If serial manipulator structures are used in mobility assistive devices, then the devices can assist with basic movements, but the payload-to-weight ratio is low and force exertion capabilities are poor
Solution Approach 1:
The system divides the mobility assistive device into multiple independent Stewart platform actuators, each capable of providing force and motion control. This segmentation allows the load to be distributed across multiple actuators rather than requiring a single heavy actuator, thereby improving the payload-to-weight ratio while maintaining force exertion capabilities
Solution Approach 2:
The Stewart platform actuators are designed to perform multiple functions: they provide both positional control and force exertion capabilities. This multi-functionality eliminates the need for separate heavy-duty force-generating components, improving the payload-to-weight ratio while maintaining strong force capabilities
2Measurement precision
If serial manipulator structures are used, then the devices can perform basic locomotion assistance, but the accuracy in positioning the payload and speed of manipulation are poor
Solution Approach 1:
The system employs dynamic control of multiple Stewart platform actuators with adjustable stiffness through damping elements. This allows the system to optimize performance for both high-precision positioning and high-speed manipulation tasks by dynamically adjusting the actuator characteristics based on the specific operational requirements
Solution Approach 2:
The system incorporates sensors that provide real-time feedback on the position and motion of each actuator. This feedback is processed by a central controller that independently controls each actuator, enabling high positioning accuracy while maintaining fast response times through closed-loop control
3Adaptability or versatility
If multiple actuators are connected in serial configuration, then the device can cover larger motion ranges, but the weight increases and force capabilities decrease
Solution Approach 1:
The system uses multiple modular Stewart platform actuators connected in series, where each actuator is a self-contained unit with its own driver and control system. This modular segmentation allows for extended motion ranges while keeping individual actuator weights manageable, as each unit independently supports a portion of the total load
Solution Approach 2:
The actuators incorporate lightweight yet strong structural materials and damping elements to achieve high strength-to-weight ratios. This allows the system to extend motion ranges with multiple actuators while minimizing the overall weight increase
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 system achieves high positioning accuracy and speed with improved payload capacity and force exertion, effectively mimicking human or animal locomotion and enhancing mobility assistive capabilities.
Implementation Method 1
The linking damper comprises a driver and a controller that is in communication with the driver to control and adjust a stiffness of the linking damper and thus stiffness of the motion system
Implementation Method 2
Linear/rotary hexapod (Stewart platform) actuators can be used to directly mimic a motion of existing industrial (Cartesian) robots
Data Source
AI summary
Examples of a motion system are disclosed. The motion system comprises a plurality of Stewart platform based actuators connected one to each another forming a desired modular configuration. Each of the plurality of actuators is controlled by a central controller that is configured to independently control the plurality actuators and adjust in real time their position, orientation and motion trajectory. The plurality of actuators are arranged in the desired configuration, shape and size to provide motion system that can mimic a natural motion/gait of human or animal body.