Periodic Reporting for period 1 - M-SCPA (Development of Soft, Efficient, Powerful, and Rapid Artificial Muscles for the Design of a Soft Wearable Haptic Exoskeleton)
Reporting period: 2021-05-01 to 2023-04-30
Soft robotics is a new branch of robotics that aims at creating robots that are compliant. The robot's compliance is usually obtained by using materials that are intrinsically soft, or through particular assembly techniques of rigid materials.
Simply put, we can use soft polymers such akin to natural rubber to design robots, or more rigid materials such as high strength fibers but knit them in a way that make a piece of fabric capable of deformation.
Soft robotics aims at creating safer, more adaptable and cheaper robots.
Because they are designed differently, soft robots do not aim at solving the same issues as traditional robots.
Traditional robots usually operate in factories and perform highly repetitive tasks. For example, in a factory lifting and assembling a car frame.
Soft robotics rather aim at bringing robotics closer to our everyday life and to solve problems that previously could not be addressed by robotics.
Our environment is filled with soft devices. The clothes & shoes you wear, the mattress you sleep on, the chair you sit on or the bag you carry.
All these things are soft precisely because our bodies are relatively soft as well. Sleeping on a hard floor is uncomfortable. Wearing a medieval plated armor is also probably both unpractical and uncomfortable.
A good example of where soft robotics is relevant is when someone is wearing an exoskeleton. Indeed, wearing an exoskeleton is akin to wearing a robot. However, if this exoskeleton was solely made of metal, it would also be heavy, uncomfortable and probably quite dangerous.
It follows then that exoskeletons are an application where soft robotics is relevant.
Other relevant applications encompass healthcare and personal assistance, where robots are in close contact with humans, and dexterous manipulation, where robots may have to grab various objects without breaking them or letting them fall.
There are, however, numerous challenges before soft robotics is ubiquitous.
One of them is creating soft actuators. We know how to manufacture actuators and motors out of hard materials. However, these technologies are largely not applicable to soft materials.
This proposal's main goals were i) to design a new soft actuator boasting improved performances, and ii) to use this actuator in a soft wearable exoskeleton used to transmit tactile information.
The proposal was divided into 4 different objectives:
-Designing High Power Density, High Bandwidth Actuators
-Designing Soft Actuators
-Designing Compact & Efficient Actuators
-Manufacturing a Soft Wearable Haptic Exoskeleton
Simply put, we can use soft polymers such akin to natural rubber to design robots, or more rigid materials such as high strength fibers but knit them in a way that make a piece of fabric capable of deformation.
Soft robotics aims at creating safer, more adaptable and cheaper robots.
Because they are designed differently, soft robots do not aim at solving the same issues as traditional robots.
Traditional robots usually operate in factories and perform highly repetitive tasks. For example, in a factory lifting and assembling a car frame.
Soft robotics rather aim at bringing robotics closer to our everyday life and to solve problems that previously could not be addressed by robotics.
Our environment is filled with soft devices. The clothes & shoes you wear, the mattress you sleep on, the chair you sit on or the bag you carry.
All these things are soft precisely because our bodies are relatively soft as well. Sleeping on a hard floor is uncomfortable. Wearing a medieval plated armor is also probably both unpractical and uncomfortable.
A good example of where soft robotics is relevant is when someone is wearing an exoskeleton. Indeed, wearing an exoskeleton is akin to wearing a robot. However, if this exoskeleton was solely made of metal, it would also be heavy, uncomfortable and probably quite dangerous.
It follows then that exoskeletons are an application where soft robotics is relevant.
Other relevant applications encompass healthcare and personal assistance, where robots are in close contact with humans, and dexterous manipulation, where robots may have to grab various objects without breaking them or letting them fall.
There are, however, numerous challenges before soft robotics is ubiquitous.
One of them is creating soft actuators. We know how to manufacture actuators and motors out of hard materials. However, these technologies are largely not applicable to soft materials.
This proposal's main goals were i) to design a new soft actuator boasting improved performances, and ii) to use this actuator in a soft wearable exoskeleton used to transmit tactile information.
The proposal was divided into 4 different objectives:
-Designing High Power Density, High Bandwidth Actuators
-Designing Soft Actuators
-Designing Compact & Efficient Actuators
-Manufacturing a Soft Wearable Haptic Exoskeleton
A rapid summary of this project's performed work follows:
-We used prior analytical models to predict the our composite theoretical strain due to the exposure of fibers to a uniform magnetic field.
-We successfully extruded soft magneto-active (MAE) fibers in 3.175 and 2mm diameters.
-We magnetized these fibers and measured remanence and Young's modulus.
-We built setups to supercoil the fibers as well as create tight copper wire solenoids around the fibers.
-We conducted actuation tests on straight fibers as well as supercoiled fibers.
However,
-We realized that the fibers' magnetic remanence was much lower than expected
-We hypothesize that this is a due to the ferromagnetic particles reorganization within the fiber after magnetization. This is likely due to our use of large particles with high Br, as well as the use of a soft elastomer matrix.
-The use of stiffer base polymers would require the use of large magnetic fields, which is contrary to the project's stated goal of creating an efficient/compact actuator, as well as, technically complicated within a small fiber form factor.
-We decided to pursue a different actuator design following the project's requirements as closely as possible.
-The new design is inspired on piezoelectric ultrasonic traveling wave actuators. However, it uses short distance magnetic field gradients and an MAE composite layer to create traveling waves.
-The MAE layer is assemble in a ring format, and the actuator is a rotating actuator instead of a linear actuator as originally planned.
-Using a combination of 2 standing waves, a traveling wave is created. The traveling wave direction is demonstratively controlled using the standing wave phase difference.
-Loads in contact with the MAE layer rotate following the traveling wave.
-This novel actuator has been characterized and our results will be submitted for a scientific publication shortly.
-We used prior analytical models to predict the our composite theoretical strain due to the exposure of fibers to a uniform magnetic field.
-We successfully extruded soft magneto-active (MAE) fibers in 3.175 and 2mm diameters.
-We magnetized these fibers and measured remanence and Young's modulus.
-We built setups to supercoil the fibers as well as create tight copper wire solenoids around the fibers.
-We conducted actuation tests on straight fibers as well as supercoiled fibers.
However,
-We realized that the fibers' magnetic remanence was much lower than expected
-We hypothesize that this is a due to the ferromagnetic particles reorganization within the fiber after magnetization. This is likely due to our use of large particles with high Br, as well as the use of a soft elastomer matrix.
-The use of stiffer base polymers would require the use of large magnetic fields, which is contrary to the project's stated goal of creating an efficient/compact actuator, as well as, technically complicated within a small fiber form factor.
-We decided to pursue a different actuator design following the project's requirements as closely as possible.
-The new design is inspired on piezoelectric ultrasonic traveling wave actuators. However, it uses short distance magnetic field gradients and an MAE composite layer to create traveling waves.
-The MAE layer is assemble in a ring format, and the actuator is a rotating actuator instead of a linear actuator as originally planned.
-Using a combination of 2 standing waves, a traveling wave is created. The traveling wave direction is demonstratively controlled using the standing wave phase difference.
-Loads in contact with the MAE layer rotate following the traveling wave.
-This novel actuator has been characterized and our results will be submitted for a scientific publication shortly.
We created a new soft actuator.
This actuator is the first to demonstrate bi-directional continuous rotation using traveling waves, as well as the first demonstration of magneto-active elastomers as a way to generate traveling waves.
Contrary to prior research on soft rotating actuators, we do not rely on a hard axle to transmit the rotation. Instead we rely on friction from the MAE layer to the soft object placed on top.
We argue that this approach is more relevant for building soft rotating machines since tight tolerances are hardly guaranteed in soft and flexible structures.
This results are relevant to the field of soft robotics because they demonstrate the opportunity that MAE composites offer to design soft and complex mechanisms.
Our approach is also compact since the electromagnetic coils are in close proximity with the MAE layer.
We expect this sort of actuators to be used in mm to cm scale manipulation or locomotion of soft objects or robots.
For example, these actuators may help larger and more traditional robots to interface with soft objects such a fruits or fabric during manipulation.
This actuator is the first to demonstrate bi-directional continuous rotation using traveling waves, as well as the first demonstration of magneto-active elastomers as a way to generate traveling waves.
Contrary to prior research on soft rotating actuators, we do not rely on a hard axle to transmit the rotation. Instead we rely on friction from the MAE layer to the soft object placed on top.
We argue that this approach is more relevant for building soft rotating machines since tight tolerances are hardly guaranteed in soft and flexible structures.
This results are relevant to the field of soft robotics because they demonstrate the opportunity that MAE composites offer to design soft and complex mechanisms.
Our approach is also compact since the electromagnetic coils are in close proximity with the MAE layer.
We expect this sort of actuators to be used in mm to cm scale manipulation or locomotion of soft objects or robots.
For example, these actuators may help larger and more traditional robots to interface with soft objects such a fruits or fabric during manipulation.