Motion Base Gravity Compensation for Force Measurement Accuracy
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Solution Overview
Problem
Conventional motion bases require heavy-duty actuators to support the entire weight of the top plate and object, leading to low natural frequency, complex actuator control systems, and high power requirements, which result in force measurement errors and inefficiencies.
Innovation Solution
A motion base design that utilizes a rotatable coupling device to support greater than 50% of the weight of the support structure, allowing for fewer and lighter actuators, and incorporating a gimbal component with two degrees of freedom to achieve high natural frequency and simpler control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heavy-duty actuators are used to support the entire weight of the top plate and object, then the motion base can support the required load, but the natural frequency decreases and force measurement errors increase
Solution Approach 1:
The patent segments the weight support function between the actuators and the gravity compensation mechanism. The gravity compensation mechanism (counterweights and springs) carries the static weight load, while the actuators only need to provide dynamic compensation forces. This segmentation allows using lighter actuators that do not degrade force measurement accuracy while still supporting the required total load.
Solution Approach 2:
The patent implements a gravity compensation mechanism using counterweights and springs that generate upward forces to counteract the downward gravitational force on the top plate and object. This anti-weight approach reduces the net load on actuators, allowing them to be lighter and less intrusive to force measurements while maintaining adequate load support capability.
2Strength
If heavy-duty actuators are used to support the entire weight, then the load can be supported, but the actuator control system becomes complex and power requirements increase
Solution Approach 1:
By introducing counterweights and springs to compensate for gravity, the actuators only need to provide dynamic compensation forces rather than supporting the entire static weight. This dramatically reduces the power requirements and simplifies the control system, as the actuators operate in a much smaller force range and do not need to continuously counteract heavy gravitational loads.
Solution Approach 2:
The gravity compensation mechanism changes the operating parameters of the actuators by reducing the static force component they must handle. This parameter change allows using smaller, less complex actuators with lower power ratings while maintaining the ability to support the required load through the combined action of gravity compensation and dynamic actuation.
3Strength
If the entire weight is supported by actuators, then load support is achieved, but the actuators must be structurally robust and numerous (4-6 actuators)
Solution Approach 1:
The patent segments the weight support function between the gravity compensation mechanism and the actuators. This segmentation allows reducing the number of actuators needed, as each actuator only needs to provide dynamic compensation rather than support the full weight. The gravity compensation mechanism handles the static load, enabling the use of fewer actuators overall.
Data Source
AI summary
A motion base for displacing a force measurement assembly is disclosed herein. The motion base includes a base assembly; a support structure configured to be coupled to the force measurement assembly; a rotatable coupling device, the rotatable coupling device rotatably coupling the support structure to the base assembly; and an actuation system, the actuation system including one or more actuators operatively coupled to the support structure, the one or more actuators configured to displace the support structure relative to the base assembly. In one or more embodiments, greater than 50% of the weight of the support structure is supported by the rotatable coupling device. Also, in one or more embodiments, the motion base may be used for displacing objects other than a force measurement assembly, such as for displacing a flight simulator or a virtual reality simulator.