Final Report Summary - NANORAC (Nano robotic for assembly characterisation)
The difficulties of handling nano-objects result first from the domination of intermolecular and adhesion forces over inertial forces at nano-scale. In particular, adhesion and electro-static forces are not well mastered because their effect is driven by the geometry of the involved objects (that is often only approximately known) and by the distribution of the electrical charges (that is most of the time completely unknown). Additionally, these forces are highly dependant on the environment conditions (temperature, humidity, vacuum
). The dynamic behaviour of the simplest nano-objects thus becomes unpredictable and elementary manipulation tasks (grasping and especially releasing) are difficult to perform. Perception is the second main barrier limiting nanomanipulation. The drastic difference between the nano- and the micro-worlds is the lack of direct imaging.
Viewing small nano-objects is only possible through non-optical tools like the scanning electron microscope (SEM), which:
- ?provides two-dimensional images with very low depth of field (insufficient for accurate positioning)
- constitutes a 'real-time' technique compatible with simultaneous manipulation
- ?operates on conducting objects inside a controlled environment (vacuum), and the atomic force microscope (AFM) allowing three-dimensional perception, albeit with scanning delays and a definitive contradiction in performing simultaneously sensing and manipulation.
In the context outlined above, the Nanorac project has defined four sub-goals:
- ?simulation: understand, model and, as far as 'usefully' possible, reproduce the dynamic behaviour of nano-scale objects in their environment;
- manipulation: develop devices and control strategies for manipulating nano-scale objects;
- human interaction: provide the human with the feedback and assistance to surpass the unfamiliarity of nano-scale manipulation;
- validation: global assessment of the developed hardware and software tools with respect to representative nanomanipulation tasks.
Regarding dynamic simulations, the project aimed to provide a realistic virtual reality (VR) environment able, in priority order, to:
(i) enhance the human manipulation skill at nano-scale,
(ii) assist in the design of manipulation devices and control strategies and
(iii) help understand the nano-scale dynamic phenomena.
A VR application featuring an interactive dynamic simulator suited to the nano-world was thus developed. It is necessarily based on the understanding and quantification of physical phenomena at nano-scale (nano-physics). It also exploits 3D perception data provided by an SEM imaging and geometric data extraction module.
The work on manipulation techniques also benefited from nano-physics investigations. Its objectives were twofold:
- Design, production and test of both a nanogripper dedicated to the handling of sub-micron objects (10 nm - 1 µm) and a microgripper for super-micron objects (100 nm - 10 µm) It is worth mentioning here the coating of grippers with CNT films as an anti-sticktion feature and the integration of CNTs on the end-effectors to adapt them to the requirements of the tasks.
- ?Develop manipulation strategies and control. This work relied on simulations of pick-up and release tasks based on an analytical model of gripping. It aimed at implementing manipulation strategies appropriate to nano-physics, but also taking into account the capabilities and limitations of the whole nanohandling system. These strategies will then lead to control schemes making use of the available position and force feedback, as well as of data provided by SEM imaging and virtual reality.
In order to assist untrained operators in the remote handling of nano-objects, the human-machine interface features haptic interactions, augmented reality and simulation capabilities. Several control modalities were initially considered, from direct control with force feedback of virtual/real nanoobjects to the use of haptics to guide the operator's hand towards a target configuration.
Finally, the validation of the Nanorac concept was based on:
(i) the specification, assembling and experimentation of a complete SEM system integrating the hardware and software components previously developed and (ii) providing arrays of evenly distributed CNTs, both vertically standing and horizontally lying, with known uniform properties for test purposes.
Viewing small nano-objects is only possible through non-optical tools like the scanning electron microscope (SEM), which:
- ?provides two-dimensional images with very low depth of field (insufficient for accurate positioning)
- constitutes a 'real-time' technique compatible with simultaneous manipulation
- ?operates on conducting objects inside a controlled environment (vacuum), and the atomic force microscope (AFM) allowing three-dimensional perception, albeit with scanning delays and a definitive contradiction in performing simultaneously sensing and manipulation.
In the context outlined above, the Nanorac project has defined four sub-goals:
- ?simulation: understand, model and, as far as 'usefully' possible, reproduce the dynamic behaviour of nano-scale objects in their environment;
- manipulation: develop devices and control strategies for manipulating nano-scale objects;
- human interaction: provide the human with the feedback and assistance to surpass the unfamiliarity of nano-scale manipulation;
- validation: global assessment of the developed hardware and software tools with respect to representative nanomanipulation tasks.
Regarding dynamic simulations, the project aimed to provide a realistic virtual reality (VR) environment able, in priority order, to:
(i) enhance the human manipulation skill at nano-scale,
(ii) assist in the design of manipulation devices and control strategies and
(iii) help understand the nano-scale dynamic phenomena.
A VR application featuring an interactive dynamic simulator suited to the nano-world was thus developed. It is necessarily based on the understanding and quantification of physical phenomena at nano-scale (nano-physics). It also exploits 3D perception data provided by an SEM imaging and geometric data extraction module.
The work on manipulation techniques also benefited from nano-physics investigations. Its objectives were twofold:
- Design, production and test of both a nanogripper dedicated to the handling of sub-micron objects (10 nm - 1 µm) and a microgripper for super-micron objects (100 nm - 10 µm) It is worth mentioning here the coating of grippers with CNT films as an anti-sticktion feature and the integration of CNTs on the end-effectors to adapt them to the requirements of the tasks.
- ?Develop manipulation strategies and control. This work relied on simulations of pick-up and release tasks based on an analytical model of gripping. It aimed at implementing manipulation strategies appropriate to nano-physics, but also taking into account the capabilities and limitations of the whole nanohandling system. These strategies will then lead to control schemes making use of the available position and force feedback, as well as of data provided by SEM imaging and virtual reality.
In order to assist untrained operators in the remote handling of nano-objects, the human-machine interface features haptic interactions, augmented reality and simulation capabilities. Several control modalities were initially considered, from direct control with force feedback of virtual/real nanoobjects to the use of haptics to guide the operator's hand towards a target configuration.
Finally, the validation of the Nanorac concept was based on:
(i) the specification, assembling and experimentation of a complete SEM system integrating the hardware and software components previously developed and (ii) providing arrays of evenly distributed CNTs, both vertically standing and horizontally lying, with known uniform properties for test purposes.
