Flexural Mechanisms for Space Applications
As the field of space exploration continues to advance, engineers and scientists are constantly searching for new technologies and materials to help improve the performance and reliability of space systems. One of the key areas of research in this field is the use of compliant mechanisms in space applications.
A compliant mechanism is a mechanical system that uses flexible elements, such as bellows or diaphragms, to provide a compliant movement. These mechanisms are able to adapt to changes in the environment and provide a level of flexibility that is not possible with traditional rigid systems. This is particularly important in the harsh and dynamic environment of space, where temperature changes, radiation, and other factors can affect the performance of mechanical systems.
These mechanisms are designed to have some degree of flexibility or compliance, which allows them to deform or bend in response to external loads or forces.
This flexibility can be used to absorb energy, reduce stresses, or enable the mechanism to adapt to changes in its environment. Some examples of compliant mechanisms include flexible joints, compliant actuators, and spring-loaded mechanisms.
They are used in a wide range of applications, including robotics, wearable technology, and construction. These can include things like flexible electronics, which are made using flexible materials such as graphene or plastic, as well as structural elements such as beams or bridges that are designed to flex or deform under load.
One of the most common applications of compliant mechanisms in space is in spacecraft and satellites for positioning and pointing applications. These systems often use flexure-based mechanisms, which use flexible elements to provide a compliant movement. This allows for precise and smooth movement in a limited space, which is essential for the proper functioning of the spacecraft or satellite.
Another common application of compliant mechanisms in space is in robotics and manipulator systems for space exploration where it is desirable to have a mechanism that is able to adapt to its surroundings or to absorb energy to protect against damage. These systems often use compliant actuators, which are special types of actuators that use flexible materials to provide a compliant movement. This allows the robotic arm or manipulator to move and adapt to its surroundings, which is essential for the success of space exploration missions.
Compliant mechanisms are also used in space structures, such as solar arrays and antenna systems, to allow for movement and adjustability. Examples of compliant mechanisms used in space applications include (comprising the above points):
- Flexure-based mechanisms: these mechanisms use flexible elements, such as bellows or diaphragms, to provide a compliant movement. They are often used in spacecraft and satellites for positioning and pointing applications.
- Compliant actuators: these are special types of actuators that use flexible materials, such as shape memory alloys or electroactive polymers, to provide a compliant movement.
- Compliant joints: these are special types of joints that use flexible elements, such as elastomers or bearings, to provide a compliant movement. They are often used in space structures, such as solar arrays and antenna systems, to allow for movement and adjustability.
Compliant scissors, also known as scissors mechanisms, are a type of compliant mechanism that use a pair of scissors or scissor-like elements to provide a flexible or compliant movement. A traditional scissor for example, functions pivoting about a linkage which is frictional and cannot be used in space for long time. Alternatively the compliant scissors are an innovative technology that has been gaining popularity in the field of space applications due to their ability to provide precise and smooth movement in a limited space, while also being able to adapt to changes in the environment and they are less prone to failure.
One of the most common applications of compliant scissors in space is in robotic arms. The scissors can be powered by electric motors or other actuators, and may be controlled by a computer or other means to achieve the desired movements or positioning or tasks.
Crimping tool is the next interesting flexural design. Unlike the traditional assembled crimping tools which are prone to fail in due course of time, the flexural crimping tools provide more advantages to crimp or compress a connector or other electrical component in space even in harsh and dynamic environments.
Another benefit of using a compliant crimping tool in space is that it can help reduce the weight of the tool. Traditional crimping tools are typically heavy and bulky, which can make them difficult to use in space. A compliant crimping tool is typically smaller and lighter, making it easier to use and transport in space. They are also used in space exploration missions, such as on the International Space Station (ISS), where they can be used to crimp connectors and other electrical components.
Thrust Controller is yet another interesting mechanism. Thrust control is a crucial aspect of space applications and a compliant thrust controller is an interesting mechanism that addresses the issue of lubricant outgassing in a low-gravity environment.
The compliant pointer device, shown above, is a device that was specifically designed for NASA.
Flexural solar array tilts are a type of solar array that use flexure-based mechanisms to provide a compliant movement, allowing the array to tilt or adjust its angle to track the sun’s movement. This technology is particularly useful in space applications, where traditional solar arrays tilts may not be able to function properly due to the lack of gravity and extreme temperature fluctuations.
The use of flexure-based mechanisms in solar arrays allows for greater flexibility and adaptability in space. The arrays can tilt or adjust their angle to track the sun’s movement, which can help increase the efficiency of the solar panels and generate more power.
Not only the reduced the weight of the system help in application but the 90° rotational systems literally needs no maintenance at all.
Flexural Scott Russell mechanism, another interesting mechanism, can be used to actuate and position solar arrays, antennae, and other space-based structures, as well as in robotic arms and manipulator systems. Unlike its counterpart, the traditional Scott Russell, flexure joints are able to withstand high levels of stress and strain and are less prone to wear and tear, which is essential for use in space where maintenance is difficult and costly.
The use of flexure joints in the Scott Russell mechanism provides a number of advantages over traditional revolute joints, making it a valuable technology for use in space where maintenance is difficult and costly.
A dial indicator is a precision measuring tool that uses a needle or pointer to display a measurement on a dial. It is commonly used in various industries for measurement tasks such as determining the position, alignment, or “runout” of a part or surface.
Recently, the use of compliant mechanisms in dial indicators has gained popularity. One of the main benefits of using compliant mechanisms in dial indicators is the ability to provide precise and accurate measurements, even in harsh space environments. In space applications, traditional dial indicators may not be able to function properly due to the lack of gravity and extreme temperature fluctuations. A compliant mechanism allows the dial indicator to adapt to these changes and continue to provide accurate measurements.
Again its simplicity and lightweight properties are major advantages over traditional ones.
The limitations of the flexural mechanism are many including limited displacements, combination of complex systems that difficult to imagine, prohibitive non-linear equations, energy storage and fatigue.
However, compliant mechanisms are a key technology in the field of space exploration, providing a level of flexibility and adaptability that is not possible with traditional rigid systems. This flexibility helps to ensure that space systems can continue to function properly in the harsh and dynamic environment of space, making them a critical component for the success of future space missions.
