Path following and control research done so far for the modular snake robots is known to have the foundational assumption that friction acts exactly at the link’s center of mass. However, inspired by the biological snakes, we observe that friction acts as an uneven distribution over the snake’s body. The paper contributes towards a general modeling of the snake robot that incorporates an eccentric point where the friction force acts on each module. Moreover, we have proposed a decentralized path following control algorithm for our general model. The proposed algorithm exploits local link-level autonomy and helps the robot maneuver smoothly for any general path curve. We apply our algorithm to four different types of path curves and find promising results in the path following.

Recently, elevation angle-based formation control, which uses elevation angle constraints to define the desired formation shape, was proposed in the literature. The control laws in this approach only use bearing measurements in agents’ local frames and are thus coordinate-free. However, local stability was established for this approach. Also, using elevation angle constraints alone can lead to ordering ambiguity in the formation shape. In this paper, we propose the use of elevation angle constraints and area constraints to define the desired formation shape for three agent systems and present a bearing-only formation control law for the system. We establish almost global stability results for the three-agent system by introducing a gain parameter κ for the area error. We analyze the effect of this gain parameter and show that by choosing a sufficiently large κ, almost global stability result can be ensured for the three-agent system. Appropriate lower bound for κ is also derived for establishing almost global stability. Agents modeled as single and double integrators are considered in our analysis, and simulations are provided to validate the proposed algorithms.

In this paper we study formation control using elevation angle rigidity for non-holonomic agents and double integrators. Elevation angle rigidity has recently been proposed to solve the bearing only formation control problem without accessing global orientation information of the agents. However, only agents modelled as single integrators were considered. Non-holonomic agents, being under actuated in nature, describe practical systems such as wheeled robots. Motivated by this, we consider non-holonomic and double integrator dynamics of the agents in this paper. First, we propose the control laws which achieve formation stabilization only using bearing measurements for non-holonomic agents and double integrators. Then local asymptotic stability is proved for non-holonomic agents, and local exponential stability is obtained for double integrator agents. Finally, simulations are presented to validate the results.

This article presents a finite-time heterogeneous cyclic pursuit scheme that ensures consensus among agents modeled as integrators. It is shown that for the proposed consensus scheme, even when the gains are nonidentical, consensus results within a finite time, provided all the gains are positive or even if one gain is negative, subject to a lower bound. An algorithm is presented to compute the consensus value and consensus time for a given set of positive gains and initial states of the agents. The set of values, where consensus can occur, by varying the gains, has been derived and a second algorithm aids in determining the positive gains that enable consensus at any point in the aforementioned set, at a given finite time. As an application, the finite-time consensus in line-of-sight rates, over a cycle digraph, for a group of interceptors is shown to be effective in ensuring co-operative collision-free interception of a target, for both constant speed as well as realistic time-varying-speed models of the interceptors. Simulations the theoretical results.