Spacecraft Pointing Platform With Three Linear Actuators
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Solution Overview
Problem
Existing devices for deploying and pointing equipment on spacecraft, such as telescopes, face challenges with insufficient rigidity for heavy loads, precision, and increased space occupation due to the geometry of linear actuators, which also struggle with launch forces and precision during orientation.
Innovation Solution
A device with three identical linear actuators connected to a mobile platform and a carrier via universal joints and screw/nut joints, allowing for precise translation and rotation, featuring a roller screw design with a lubricant-retaining sheath and flexible elements to manage launch forces through additional support points, enhancing precision and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If linear actuators with mandrels and linear elements are used for deploying and pointing equipment, then the device can achieve movement and orientation control, but the linear elements cannot provide sufficient rigidity for heavy loads or massive instruments
Solution Approach 1:
The actuator is divided into two separate portions: a first portion connected to the mobile platform and a second portion connected to the carrier. These portions can be independently optimized - the first portion can be designed for high rigidity to support heavy loads, while the second portion can be designed for compact winding on the mandrel. This segmentation resolves the contradiction by allowing each part to specialize in one function rather than requiring a single component to satisfy both conflicting requirements.
Solution Approach 2:
The invention introduces a spatial separation between the rigid linear element (first portion) and the winding mechanism (second portion). By distributing these functions across different spatial locations and connecting them through a universal joint, the system achieves both rigidity where needed and compactness where space is constrained, effectively resolving the contradiction through dimensional arrangement.
2Strength
If rigid linear elements are developed to provide sufficient rigidity, then the actuators can support heavy loads, but it becomes difficult to wind them on mandrels and requires mandrels with relatively large radius, which increases space occupation
Solution Approach 1:
The linear actuator is segmented into a first portion (rigid linear element) and a second portion (winding portion). The first portion maintains high rigidity for supporting heavy loads, while the second portion is specifically designed to be wound compactly on the mandrel. This segmentation allows the rigid element to be as long and stiff as needed without compromising the compactness of the stored configuration, as only the second portion requires winding.
Solution Approach 2:
The invention separates the rigidity function (first portion) from the winding function (second portion) in space. The first portion can extend far from the mandrel to provide the necessary stiffness for heavy loads, while the second portion wraps tightly around the mandrel for compact storage. This spatial separation resolves the contradiction between requiring long rigid elements and maintaining compact stowage volume.
3Volume of moving object
If the mobile platform is positioned outside the field of operational movement for stacking, then space is optimized, but the equipment item may collide with other components of the spacecraft
Solution Approach 1:
The universal joint connected to the first portion of each actuator provides dynamic adaptability, allowing the first portion to change its orientation and position during deployment. This dynamic capability enables the mobile platform to follow a controlled deployment path that avoids collisions with other spacecraft components, while still achieving the desired stacked position for space optimization.
Solution Approach 2:
The universal joint allows the first portion to change its angular parameters during deployment, enabling the system to navigate around obstacles. By dynamically adjusting the orientation parameters of the actuator portions, the mobile platform can be positioned in the optimized stacked location without colliding with other components, resolving the contradiction between space optimization and collision avoidance.
4Strength
If actuators are designed for heavy loads with high rigidity, then load capacity increases, but the device becomes more sensitive to forces generated during launch
Solution Approach 1:
The actuator is segmented into a first portion for load support and a second portion for actuation. The first portion can be designed with high rigidity for heavy load capacity, while the second portion can be designed to be more compliant or flexible to absorb launch forces. This segmentation allows the system to handle both heavy loads and launch vibrations effectively, resolving the contradiction between load capacity and launch force resistance.
Solution Approach 2:
The universal joint introduces a degree of freedom that allows the first portion to adjust its orientation in response to launch forces. This parameter change capability enables the rigid first portion to maintain its load-bearing function while accommodating vibrations and shocks during launch, effectively resolving the contradiction between high load capacity and sensitivity to launch forces.
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 solution provides high precision in positioning and orientation while withstanding launch forces, reducing the need for overdesigning actuators, thus maintaining accuracy and reducing mass and cost.
Implementation Method 1
a screw/nut joint interconnecting the first and second portion, the universal joint of each actuator being suitable for preventing rotation about the axis of the screw/nut joint, such that rotational actuation of the screw or nut by the motor causes a translational movement between the first and the second portion
Implementation Method 2
the universal joint of each actuator being suitable for preventing rotation about the axis of the screw/nut joint
Implementation Method 3
featuring a roller screw design with a lubricant-retaining sheath and flexible elements to manage launch forces
Data Source
AI summary
A device for deploying and pointing an equipment item is disclosed including a mobile platform for receiving the equipment item, a carrier integrally secured to a wall of a spacecraft, and three identical linear actuators which connect the carrier to the mobile platform and are suitable for moving the platform in translation along one axis and for orienting the platform in rotation about two axes. Each linear actuator including a first portion connected to the platform by a universal joint, a second portion connected to the carrier by a pivot connection, a motor, and a screw/nut joint interconnecting the two portions, each universal joint being suitable for preventing the screw/nut joint from rotating about the axis, such that driving the motor causes a translational movement between the first and the second portion.