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In formation control, triangular formations consisting of three autonomous agents serve as a class of benchmarks that can be used to test and compare the performances of different controllers. We present an algorithm that combines the advantages of both position-and distance-based gradient descent control laws. For example, only two pairs of neighboring agents need to be controlled, agents can work in their own local frame of coordinates and the orientation of the formation with respect to a global frame of coordinates is not prescribed. We first present a novel technique based on adding artificial biases to neighboring agents’ range sensors such that their eventual positions correspond to a collinear configuration. Right after, a small modification in the bias terms by introducing a prescribed rotation matrix will allow the control of the bearing of the neighboring agents.

Scanning probe microscopy (SPM) technology plays the irreplaceable role in investigating micro/nano world, which has been bringing tremendous development opportunities to various fields. To enhance maneuverability, SPM can be modified into a nanomanipulation system with its scanning probe as the end-effector. The probe is commonly mounted on smart material based actuators to generate precise motion with nanometer level resolution. However, instinctive hysteretic characteristics ubiquitously exist in smart material actuators, which degrade their arbitrary positioning precision. To effectively represent and further reduce complex hysteretic effects, this paper proposes to utilize the modified Prandtl-Ishlinskii (PI) model: extended unparallel PI (EUPI) model, which possesses advantages such as the flexible modeling capability (compared to the prevalently implemented modified PI models) and the easy-to-use property for construction and identification (compared to the well known Preisach model and the Generalized PI (GPI) model). To effectively reduce complex hysteresis, the EUPI model based compensator (IMUPIcompensator) is required to be flexible and precise. To efficiently design such a compensator satisfying stability requirement, this study proposes a systematic approach, including stabilizing gain selection and analytical calculation of boundary gains of the EUPI irreversible component. As a demonstration, satisfactorily precise IMUPIcompensator was established according to this systematic design approach and tested through simulations on rectifying Atomic Force Microscopy (AFM, one special SPM) imaging process distorted by complex hysteresis.

A quantitative modeling approach is developed to dissect the signaling pathways involved in the process of the epidermal growth factor (EGF)-induced dynamic change of cell adhesion. The dynamics model will be constructed based on a system identification process, which is regularly employed in control system design to elucidate the unknown structures and parameters of some of the components in the system based on the prior knowledge and the input/output information of the system. The signaling network that is known to regulate the EGF-induced cell adhesion is designated as the controller which controls the physical process of cell adhesion, i.e. the plant. A nanomechanical sensor in quartz crystal microbalance with dissipation monitoring (QCM-D), which is capable of generating realtime, continuous and measurable signals, will be used for evaluating the system output. The interaction of measurement signal with the cell adhesion complex is modeled as plant. From the model, key structures and parameters of the signaling hierarchy were identified and confirmed. The dynamic pathway output agrees well with the measurement result of energy dissipation from the QCM-D sensor. We expect this proposed study will reveal the decisive reactions of the signaling network that are most critical to regulation of EGF-induced changes in cell adhesion at both normal and disease conditions.