Satellite Gripper With Counter-Threaded Screw Drive
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Solution Overview
Problem
Existing satellite grippers face challenges in synchronizing with launch adapter rings (LAR) due to their rigidity and varying cross-section shapes, leading to positioning errors during satellite servicing in microgravity environments.
Innovation Solution
A gripper design featuring two counter-directional carts with linear roller guides driven by a screw gear, equipped with retractable fingers and optical sensors, allowing for independent finger movement and adaptive grasping of differently shaped adapters without precise initial positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional gripper design with fixed finger guides is used, then the structure is simple and easy to manufacture, but it cannot adapt to adapters with different cross-section shapes
Solution Approach 1:
The finger guides are made movable relative to the support structure, allowing them to change their angular position dynamically. This enables the gripper to adapt to different adapter cross-section shapes by adjusting the finger guide angles, while the overall structure remains relatively simple through the use of rotational joints rather than completely redesigning the gripper for each adapter type.
2Manufacturing precision
If the gripper requires precise initial positioning relative to the satellite, then gripping accuracy is high, but the complexity of synchronization control increases
Solution Approach 1:
The gripper uses the adapter itself as a reference for positioning. The finger guides automatically orient themselves to match the adapter's geometry through their movable design, eliminating the need for complex external synchronization control systems. The adapter's own features (such as its cross-section shape) serve as the positioning reference, reducing control complexity while maintaining high positioning accuracy.
3Strength
If rigid finger guides are used, then the structural strength is high, but the ability to compensate for positioning errors is reduced
Solution Approach 1:
The finger guides are designed with rotational joints that allow them to move and adapt their orientation. This dynamic capability enables error compensation by allowing the finger guides to adjust their position to match the actual adapter geometry, while the structural strength is maintained through proper mechanical design of the joint connections and support structure.
4Adaptability or versatility
If the gripper is designed for one specific adapter type, then the design is simple and reliable, but it cannot grip adapters with different cross-section shapes
Solution Approach 1:
The movable finger guides allow the gripper to adapt its configuration for different adapter types while maintaining reliable gripping. The dynamic adjustment capability enables the same gripper structure to reliably grip various adapter cross-section shapes by optimizing the finger guide angles for each specific adapter type, thus achieving both versatility and reliability.
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 gripper simplifies satellite gripping by enabling quick and efficient adaptation to various adapter shapes, maintaining a secure grip without continuous motor power and reducing the risk of adapter escape, even with initial positioning inaccuracies.
Implementation Method 1
Each finger (10) in its free state, i.e. without contact with the adapter (11) of the satellite being gripped, extends from its cart (2 and 3) through the action of an extendable coil spring (12) spanning between the finger (10) and the support structure (1)
Implementation Method 2
The sensors (19) detecting the presence of the adapter (11) in the grasping envelope (15) are optical sensors, advantageously operating in the infrared range
Implementation Method 3
The carts (2 and 3) are driven by a screw gear which consists of a drive shaft (5), which is counter-threaded on both sides, and of a first (6) and a second (7) nut mounted rigidly on the first (2) and the second (3) cart, respectively
Implementation Method 4
two counter-directional carts (2 and 3) moving on linear guides (4) mounted on support structure (1)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The gripper consists of a support structure (1) with two counter-directional carts (2, 3) moving on the support structure along linear guides (4). The carts (2, 3) are driven by a screw gear in the form of a drive shaft (5) which is counter-threaded on both sides, and of two nuts (6, 7) connected with the carts (2, 3). Each cart (2, 3) consists of two linear finger guides (8) situated at the same angle (α) relative to the axis (9) of the support structure guides (4). On the guides (8) are mounted are retractable fingers (10) which extend from the carts (2, 3) through the action of the springs (12). The flat central section of the support structure (1), parallel to the axis (9) of the guides (4) of the support structure (1), and the fingers (10) of the carts (2, 3) delineate the bottom (13) and two sides (14) of the grasping envelope (15) of the satellite, respectively. The entrance into the grasping envelope (15) is situated opposite to its bottom (13) and is equipped with optical sensors (19) detecting the presence of the adapter (11) of the satellite being gripped. Each finger (10) has a distal end (16) and a proximal end (17) relative to the entrance into the grasping envelope (15). The two sides (14) of the grasping envelope (15) are delineated by the gripping surfaces (14') of the fingers (10) which are substantialy perpendicular to the bottom (13) of the grasping envelope (15). The gripping surface (14') of each finger (10) in the vicinity of the proximal end (17) of the finger (10) has a protrusioin (18) directed towards the grasping envelope (15).