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Snake-like Robotic Modeling and Navigation » Scholar Lounge

In in the present day’s put up,  Bhavik M. Patel from IIT Guwahati shares his strategy to mannequin a snake robotic and take a look at the mannequin with completely different management methods for varied environmental situations. Over to you Bhavik… 

Desk of Contents

How did we come throughout this mission?

My analysis is centered across the movement management of snake robots. I’ve been drawn to the concept of tackling this problem by way of Simscape, which permits for the bodily illustration and visualization of the robots with out delving into the detailed dynamics. Someday, throughout a MathWorks workshop on digital twin expertise hosted on the Indian Institute of Expertise Guwahati (IIT Guwahati), I had the chance to interact with Dr. Monalisa Pal. Our dialog about my analysis led to her proposing the Snake-like Robotic Modeling and Navigation mission, which is part of MATLAB and Simulink Problem Initiatives Hub. This mission opened a brand new perspective for my work.

Who’re we?

This work is carried out by me (Bhavik M. Patel). I’m a Ph.D. pupil on the Mechatronics and Robotics Lab, Division of Mechanical Engineering, IIT Guwahati. I’m engaged on the dynamics and movement management of the underwater snake robotic underneath the supervision of Prof. Santosha Okay. Dwivedy.

What motivated me to review this subject?

I’m immersed within the thrilling area of bio-mimetic robotics, which goals to emulate the adaptability of dwelling creatures in unsure environments. Present analysis on bio-mimetic robots contains movement research, modeling movement dynamics, organic management schemes, bioinspired optimization algorithms, and many others. My focus on this research is on the serpentine movement and its management, as snakes are one of many diversified creatures discovered on land, water, and air. My goal right here is to grasp their movement dynamics and management by using Simscape to simulate a real-time digital testing floor for these robots.

A bit of bit about snake-like robots

Typically, we will observe the snake’s attribute serpentine or lateral undulation movement whereas it strikes on land or underwater. This movement is used for the event of the snake robotic on this mission. Throughout the robotic, actuators play a vital function in producing joint movement. Attaining a coordinated serpentine movement requires all joints to function in sync, necessitating using a controller for joint movement management. It’s value mentioning that snake robots with N hyperlinks possess joints and (N + 2) levels of freedom, leading to an under-actuated system, which presents an intriguing management problem.

This part gives an outline of the Simscape mannequin of the robotic and its related controllers that I developed as part of this mission. I referred to the literature [1-4] to acquire the physics behind the snake robotic. It explains that the movement of the snake robotic is delicate to environmental situations, particularly friction. The mathematical formulation of the snake’s conduct, subjected to nonlinear environmental situations, is defined within the literature. On this work, I targeted on a snake robotic, comprising of hyperlinks of uniform dimension, and on its planar movement.

Hyperlinks and Joints

The underlying modeling of the snake robotic block, with hyperlinks and joint connections, is illustrated in Determine 1. I used a revolute joint between subsequent hyperlinks, the place every hyperlink is created from the solid-block perform. This link-joint construction makes up the under-actuated system which has 9 hyperlinks, 8 joints, and 11 levels of freedom.

Determine 1: Snake modeling in Simscape

Interplay between snake and floor

For real-world situations, I thought-about joint frictions inside the Simscape revolute joint blocks. This friction represents the interplay between the snake robotic’s hyperlinks and the floor and is chargeable for driving the robotic’s movement. This frictional pressure is inherently nonlinear and may be utilized to every hyperlink by way of the planar joint, which basically acts as some extent of contact between the robotic’s hyperlinks and the floor.

Body of reference

A rework sensor is used for measuring the states of every hyperlink. The measurement is taken into account on this planet body for the simplicity of the reason.

Controller Design

Determine 2 illustrates the mannequin to regulate the movement of the snake robotic. As enter to this mannequin, the pinnacle’s reference angle is supplied by the person by way of a Simulink knob block. The remaining hyperlinks of the robotic observe the pinnacle’s actions.

Determine 2: Controller modeling in Simulink

The controller is the mind of the robotic. It decides how a robotic ought to transfer within the varied environments primarily based on the acquired suggestions by way of states. Right here, completely different management logics are used for 2 completely different features of the robotic (Joint Management and Head Management), each contributing to its movement.

Joint Management

The joint movement is managed by a PD controller. PD management receives suggestions from the snake robotic joint by way of angle. There’s a want for the reference joint place to trace the joint place of the snake robotic. The joint reference place is generated utilizing the next easy sine wave equation.

the place represents the actual joint and the section angle of the generated serpentine movement.

The pinnacle hyperlink reference joint may be generated utilizing the next equation.

the place is an offset angle. To alter the general path of the robotic, the offset angle () of the pinnacle hyperlink must be adjusted. Then, all the following hyperlinks will then observe accordingly.

The PD controller for every joint is taken into account as given under.

Head Management

A devoted controller strategy is devised particularly for the pinnacle hyperlink to regulate the robotic’s path. This controller is designed primarily based on a head error tracking-based management scheme [1], and the equation for the pinnacle controller is given under.
the place represents the error between the precise head angle and reference head angle (given by the person by way of the Simulink knob in Determine 2).

The snake robotic strikes on given reference head angle.

Visualizing the snake’s movement

The 3D visualization of the generated movement is proven in Determine 3.

Determine 3: 3D Visualization of the Movement of the Snake Robotic Mannequin

Head hyperlink place in X-Y body

The pinnacle hyperlink place of the snake robotic is given proven in Determine 4. Right here, I thought-about the reference angle with respect to the worldwide X-axis. I moved the knob first to a constructive angle, then to zero, then to a detrimental angle, and as soon as once more to zero. The pinnacle of the snake robotic strikes within the reference head angle and your entire robotic strikes in that path.
Head link position in X-Y frame

Determine 4: Head hyperlink place in X-Y body

Head angle error monitoring

Determine 5 reveals the error monitoring in head angle. The spikes present the sudden adjustments of the knob. The designed head angle monitoring controller is rather more strong which makes error monitoring to zero immediate. The zero error depicts that the pinnacle of the snake robotic is moved to the reference head angle. This manner, the robotic will get became an XY aircraft.
Head angle error tracking

Determine 5: Head angle error monitoring

Torque on the pinnacle hyperlink joint

Determine 6 reveals the torque utilized on to the pinnacle hyperlink joint. The variation in torque on account of change in reference joint head angle. This may assist a robotic for turning.
Torque on the head link joint

Determine 6: Torque on the pinnacle hyperlink joint

A Simscape mannequin for the snake robotic has been designed, the place friction forces are utilized to every hyperlink by way of planar joints. A PD controller manages joint actions, and a separate devoted controller steers the robotic. The Simulink knob features like a distant, figuring out the pinnacle’s path, with the remainder of the robotic following in a train-trail movement.

Utilizing this platform, we might simply take a look at the mannequin with completely different management methods for varied environmental situations with out explicitly implementing the snake robotic dynamics. Therefore, it’s extra user-friendly to implement real-world situations utilizing Simscape.

We want to prolong this mission to digital actuality, sooner or later, the place a vision-based controller may be designed.

MathWorks Problem Initiatives Program helped me loads in my analysis work. Other than this mission, I additionally realized work with GitHub. The dialogue with Dr. Roberto Valenti was insightful and helped me loads to finish this mission. My total expertise with this program is superb and I additionally suggest a lot of my mates to take part on this.


I thank Dr. Roberto G. Valenti for steady help and dialogue on bettering the snake robotic management scheme and Dr. Monalisa Pal for introducing this wonderful mission.

The feedback for the advance are welcome. Contact: Bhavik M. Patel (bpatel@iitg.ac.in; bpatel2195@gmail.com).


  1. Kohl, A. M., Kelasidi, E., Mohammadi, A., Maggiore, M., & Pettersen, Okay. Y. (2016). Planar maneuvering management of underwater snake robots utilizing digital holonomic constraints. Bioinspiration & biomimetics, 11(6), 065005.
  2. Mohammadi, A., Rezapour, E., Maggiore, M., & Pettersen, Okay. Y. (2015). Maneuvering management of planar snake robots utilizing digital holonomic constraints. IEEE Transactions on Management Techniques Expertise, 24(3), 884-899.
  3. Mukherjee, J., Mukherjee, S., & Kar, I. N. (2017). Sliding mode management of planar snake robotic with uncertainty utilizing digital holonomic constraints. IEEE Robotics and Automation Letters, 2(2), 1077-1084.
  4. Patel, B. M., &, Dwivedy, S.Okay. (2023). Digital holonomic constraints primarily based tremendous twisting sliding mode management for movement management of planar snake robotic within the unsure underwater atmosphere. Proceedings of the Establishment of Mechanical Engineers, Half I: Journal of Techniques and Management Engineering, 237(8),1480-1491.



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