Formal Verification of Robotic Cell Injection systems up to 4-DOF using HOL Light

Cell injection is an approach used for the delivery of small sample substances into a biological cell and is widely used in drug development, gene injection, intracytoplasmic sperm injection and in-vitro fertilization. Robotic cell injection systems provide the automation of the process as opposed to the manual and semi-automated cell injection systems, which require expert operators and involve time consuming processes and also have lower success rates. The automation of the cell injection process is obtained by controlling the orientation and movement of its various components, like injection manipulator, microscope etc., and planning the motion of the injection pipette by controlling the force of the injection. The conventional techniques to analyze the cell injection process include paper-and-pencil proof and computer simulation methods. However, both these techniques suffer from their inherent limitations, such as, proneness to human error for the former and the approximation of the mathematical expressions involved in the numerical algorithms for the latter. Formal methods have the capability to overcome these limitations and can provide an accurate analysis of these cell injection systems. Model checking, i.e., a state-based formal method, has been recently used for analyzing these systems. However, it involves the discretization of the differential equations capturing the continuous dynamics of the system and thus compromises on the completeness of the analysis of these safety-critical systems. In this paper, we propose a higher-order-logic theorem proving (a deductive-reasoning based formal method) based framework for analyzing the dynamical behavior of the robotic cell injection systems upto 4-DOF. The proposed analysis, based on the HOL Light theorem prover, enabled us to identify some discrepancies in the simulation and model checking based analysis of the same robotic cell injection system.