Robot Mechanism And Control


Multi-module Robot for Climbing Big Step-like Obstacles

A novel compliant robot is proposed for traversing on unstructured terrains. The robot has a set of modules where each module contains a trunk or link and an active wheel-pair, and it is connected to the adjacent module using a passive joint. This type of robots are inherently lightweight and provide high durability due to the absence of actuators at the link joints. However, they have limited climbing ability due to tendency of tipping over while climbing big obstacles. In order to overcome this disadvantage, the use of compliant joints is proposed in this work. Spring stiffness of each compliant joint is estimated by formulating an optimization problem using the static equilibrium equations of the robot. This is one of the key novelties of the proposed work. A design methodology is also proposed for developing an n-module compliant robot for climbing given height on a surface with prescribed coefficient of friction. The efficacy of the proposed formulation is illustrated for climbing big obstacles and traversing uneven terrains using simulation of 3- and 5-module robots. The robot is successfully able to climb maximum heights of 17 cm and 36 cm using 3 and 5 modules, respectively. Mechanical and electrical design of the robot is conceived, and a working prototype of the robot is developed. Simulation results are validated using the prototype.

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Related Publications:

  1. An optimal wheel-torque control on a compliant modular robot for wheel-slip minimization Avinash Siravuru, Suril V Shah and K. Madhava Krishna Robotica 2015 Download pdf
  2. Stair Climbing Using a Compliant Modular Robot Sri Harsha Turlapati, Mihir Shah, Phani Teja Singamaneni, Avinash Siravuru, Suril Vijaykumar Shah and K. Madhava Krishna IROS 2015 Download pdf
  3. A Compliant Multi-module Robot for Climbing Big Step-like Obstacles S. Avinash, A. Srivastava, A. Purohit, S. V. Shah and K. Madhava Krishna ICRA 2014 Download pdf


Passive And Active Suspension Based Climbing Mechanism

In this work a novel suspension mechanism for rough terrain mobility is proposed. The proposed mechanism is simpler than the existing suspension mechanism in the sense that the number of links and joints has been significantly reduced without compromising the climbing ability of the rover. We explore the use of compliant elements like springs for passively controlling the degree of freedom of the proposed mechanism and a framework for optimizing the spring parameters has been proposed. A performance evaluation of the proposed mechanism has been shown in terms of extensive simulations.

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Related Publications:

  1. A Novel Compliant Rover for Rough Terrain Mobility Arun Kumar Singh, Rahul Kumar Namdev, Vijay Eathakota, K Madhava Krishna. IROS 2010 Download pdf


Force control of Hybrid wheeled legged vehicle

We aim to study the role of force control vis-a-vis other control methodologies such as posture for wheeled legged vehicles moving on uneven terrain with slopes and possibly stairs. Here we focus on the development of a control methodology for Hybrid Wheel Legged Vehicles (HWLV) to improve the mobility of the vehicle on a given surface. A control strategy including the control of the contact forces of the vehicle with the surface is proposed. As an outcome of the development, we also analyze the conditions which lead to a rigidly suspended vehicle being incapable of moving on a surface. This advocates the need for articulated suspension and the use of a force feedback control to generate required contact forces to traverse a given terrain.

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Related Publications:

  1. Two Models of Force Actuator based Active Suspension Mechanisms for Mobility on Uneven Terrain Vijay P. Eathakota, Arun K Singh and K Madhava Krishna. Acta Astronautica, Elsevier, 2010 Download pdf
  2. Evolution of a Four Wheeled Active Suspension Rover with Minimal Actuation for Rough Terrain Mobility Arun Kumar Singh, Vijay Prakash Eathakota K Madhava Krishna, and Arun.H.Patil. ROBIO 2009 Download pdf
  3. Optimal Posture Control for Force Actuator Based Articulated Suspension Vehicle for Rough Terrain Mobility Vijay P Eathakota, S Kolachalama and K Madhava Krishna. CLAWAR 2008 Download pdf
  4. Force Actuator based Articulated Suspension Vehicle for Rough Terrain Mobility Vijay P. Eathakota, Srikanth Kolachalama, Arun K. Singh and K Madhava Krishna. ISMCR 2008 Download pdf
  5. On Improving the Mobility of Vehicles in Uneven Terrain Siddharth Sanan, Nageshwar Rao, K Madhava Krishna and Sartaj Singh. ICAR 2007 Download pdf


Extension of RS Paths to a Robot with Front and Rear Wheel Steer

Reeds and Shepp (RS) in their seminal work showed how to construct optimal paths for a car-like robot or a robot respecting car like kinematics. In this research we present an algorithm for extending RS paths for a robot with both front and rear wheel steer. Such an extension of the configuration set would increase the size of the final configuration set achievable by a path that is optimal in free space.

Related Publications:

  1. Extension of Reeds & Shepp Paths to a Robot with Front and Rear Wheel Steer Siddharth Sanan, Darshan Santani, K Madhava Krishna and Henry Hexmoor.ICRA 2006 Download pdf