Sensorless Full Body Active Compliant 6-dof PM
In modern operations, humans train, collaborate and interact with the manipulators in order to maximize the productivity and the quality of the final product. The critical factor in this human-robot interaction is safety and the ability of the mechanism to comply with human intentions. It thus becomes a necessity for the manipulator to detect external disturbances and interactions, and be able to react accordingly. In this research, a methodology for sensor-less full body active compliance is proposed on a 6-DOF RSS (Rotary-Spherical-Spherical) parallel manipulator. By using the proposed approach, the manipulator can detect and comply with the external forces on any part of its body without using any explicit force/torque sensor at the joint or the end-effector. This is done by utilizing the estimated joint torque based actuator current feedback only. A three-layer cascaded impedance controller for active compliance and reaction to various human interactions are reported. The proposed design and unique methodology for compliance exhibits an effective and inexpensive yet reliable alternative to be used in safe human-robot interactions and force controlled manufacturing applications.
Force/Position Control of 3 DOF Delta Manipulator with Voice Coil Actuator
Parallel manipulators are widely used in the industries for several applications. Due to its precision in motion as well as its robustness, parallel manipulators have proved its advantage over serial manipulators. In this paper, a 3DOF parallel manipulator is presented and force control of the manipulator is demonstrated. The proposed manipulator uses a direct drive voice coil arc actuators to achieve compliance required for human-robot interaction or soft mechanical manipulations. Its implementation in the proposed delta manipulator is discussed in the paper. The paper has discussed a unique method of controlling position as well as the force at the end-effector of the delta manipulator. The method used in making the manipulator compliant does not need an explicit force sensor and is convenient to implement. The method is inexpensive and works satisfactorily in a human interactive environment which is demonstrated through experiments discussed in the paper. The proposed design finds its application in robot-assisted assembly, surface finishing, cooperative manipulation, haptics etc.
Design, trajectory generation and control of a research quadrotor platform using ROS
We describe the modeling, estimation and control of a quadrotor in 3D environment using the 3DR Pixhawk PX4 as controller through Robot Operating System. The paper discusses a method to measure moment of inertia of quadrotor about its principal axes to achieve better results in an inexpensive way. The proposed test rig also helps in tuning the control parameters of the quadrotor.
We also present the trajectory generation and segment optimization of the trajectory commanded to the quadrotor. We describe a method of controlling the quadrotor through ROS by providing necessary inputs to the flight controller using the built-in firmware.
Keywords: Quadrotor, minimum snap trajectory, ROS controller, trajectory optimisation
THE ROBOTICS SOCIETY OF BIT MESRA
Team Robolution is a group of ingenious students from different branches with a common purpose-“DEXTERING ROBOTICS”. The club’s aim is to instill robotics temperament among our fellow students and for this, the club involves members as early as possible in various hands-on and multi-disciplinary collaborative experience in designing, building, and programming robots. The club conducts various workshops on these topics for the first and second year students . The club provides a platform where students get to implement their theoretical engineering knowledge into practical use and for this the team conducts many robotics events in the university’s technical fests.
A part of our club, ‘Team Pratyunmis’ , is the official ABU ROBOCON participating team of BIT Mesra which is the largest robotics competition in Asia Pacific. Well defined goals, an organized and disciplined work structure and motivated members is what has helped the club to grow to the present level.