Somajoyti Majumder

SCARA based peg-in-hole assembly using compliant IPMC micro gripper

Robotic assembly is difficult as there always exist position errors between two mating parts. Compliance is added in a selective compliant assembly robot arm (SCARA) in the form of a two ionic polymer metal composite (IPMC) fingers based micro gripper. This micro gripper is integrated at the end effector position of a SCARA robot. Peg-hole interaction is analytically modeled and based on it the force required to correct the lateral and angular errors by IPMC is calculated. A proportional-derivative (PD) controller is designed to actuate the IPMC to get the desired force for correcting the peg position before assembly. Simulations and experiments were carried out by developing an IPMC micro gripper and using it to analyze various cases of peg in hole assembly. The experimental results prove that adding compliance through IPMC helps in peg-in-hole assembly.

Multiple path generation by a flexible four-bar mechanism using ionic polymer metal composite

This article presents a novel design of a flexible four-bar crank–rocker mechanism using ionic polymer metal composite for generating multiple paths, which can be applied in microassembly. In order to control the deflection of links and the resultant path, active ionic polymer metal composite patches are fixed on the coupler and are actuated by a voltage (0–3 V direct current). The main focus of this article is to determine the number, size, and location of the ionic polymer metal composite patches to be used on the coupler to get a desired path. A dynamic model of the mechanism is made in ADAMS software and the design parameters are identified. A mathematical model of ionic polymer metal composite patch is developed through experiments to achieve the bending moment relationship with voltage, and this is used while simulating its behaviors. The simulation results show that the proposed mechanism can generate multiple paths, using different voltages for ionic polymer metal composite activation. The proposed mechanism is then fabricated, and experiments are carried out to compare the experimental and simulation results. It is proved that the proposed new mechanism is superior to earlier designs of four bars using ionic polymer metal composite, and the paths generated can more effectively be controlled.

Development of piezoelectric actuator based compliant micro gripper for robotic peg-in-hole assembly

Piezoelectric actuator can be used for handling and grasping of miniature parts in micro manipulation or robotic assembly where design of micro gripper is a critical issue because the object has to be inserted straightway into a hole during robotic peg-in-hole assembly. In this paper, the compliant micro gripper is designed using bimorph piezoelectric actuators along with a 3-degrees of freedom (DOF) based micro manipulation system. The analyses of piezoelectric based micro gripper and micro manipulation system are carried out which can provide the precise positioning of object during robotic micro assembly operations for shifting it from one to another hole position in a large work space (100 mm × 100 mm). By developing a prototype, it is demonstrated that piezoelectric actuator based compliant micro gripper is capable of handling different pegs and it can perform the robotic peg-in-hole assembly in a large work space.

Design principles of the locomotion mechanism of a wall climbing robot

Most of the present wall-climbing robots are either wheel or tracked wheel based. They cannot negotiate bumps or corners in their path. Other present linkage driven wall climbers are over-actuated mechanisms. We propose a linkage driven underactuated wall climbing mechanism. The locomotion technique is based on the rowing principle of the boat. A comparison of different adhesion techniques is also narrated in this paper. The present work proposes a pneumatic suction based wall climbing robot for non destructive testing of tall structures. The design principle of a novel spring assisted locomotion mechanism is described in this paper.

Rotary-Wing Flying Robot Attitude Controller for Hovering

This paper addresses the control of dynamic behavior of the rotary wing flying robot in hover, which is complex in shape and motion as nonlinear aerodynamic forces and gravity acts on the system. Due to limited accuracy of the dynamic model, the attitude dynamics is conditionally stable where a minimum amount of attitude feedback is required for system stability. To compensate for conditional stability, a controller for both roll and pitch dynamics is developed adopting cascade control loop feedback architecture where INS system feedback is used for outer control loop while the gyro feedback is adopted for the inner control loop to attain a high bandwidth, ensuring attitude stability with accelerated response required for a steady hover. The provided solution is tested on Hirobo Scheadu50 model and the system performance is analyzed during hover using the proposed controller. Through taut integration of simulation and flight-test validation, a controller is developed that is sufficiently accurate, quite effective and simple enough for handling complex and changing rotorcraft dynamics in hover.

Stability Analysis of Piezoelectric Actuator based Micro Gripper for Robotic Micro Assembly

Piezoelectric actuator can be used for handling and grasping of miniature parts by developing a micro gripper in micro manipulation system or robotic assembly where study of stable displacement and force characteristics with voltage signal are important. In order to obtain these behaviors using voltage signal, electromechanical characterization of piezo actuator is required for developing a micro gripper. In this paper, a stability analysis is carried out by establishing equivalent behavior using combination of two piezo ceramic layers and one resistive layer between them where we are applying a voltage signal (±60V) through a proportional-integral-derivative (PID) controller. By conducting experiments, it is verified that the piezo actuator attains stable behavior by adjusting gains which produces the maximum deflection upto 1.5 mm. The maximum force generation capability is upto 0.203 N by applying a voltage range of ±60V. A piezo actuator based micro gripper is developed for handling and grasping of the miniature parts.

Rotary-wing aerial robot configuration for in-flight switching for hovering

This paper describes the configuration of Rotary Wing Aerial Robot developed at CSIR-CMERI for smooth switching while in flight from teleoperated mode to auto mode for steady hovering. This include reading incoming PWM signals from transceiver using high-speed digital FPGA card mounted on the control computer to allow for high-speed data throughput required for switching and ensuring attitude stability with accelerated response required for a steady hover. An indigenous protocol is developed for powerful long distance communication between ground station and RWAR for command, reply and data transmission from a high performance MEMS based miniature Attitude Heading Reference System (AHRS) with GPS. The provided configuration is tested on Hirobo Scheadu50 model.

Robotic micro assembly by compliant piezoelectric micro grippers in multi mobile micro manipulation system

In order to attempt on multiple robotic micro assemblies of miniature parts, the handling and grasping are the critical parameters while designing the micro manipulation system (MMS). In this paper, a novel design of multi mobile MMS is proposed where handling and grasping are performed using compliant bimorphs piezoelectric micro grippers. These grippers provide self adjustment of peg misalignment during pick and place and peg-in-hole assembly where the bimorphs piezoelectric actuator has bi-directional actuation capability during handling for a long time as well as high force generation capability for grasping. The analysis of mobile MMS and piezoelectric micro gripper are carried out which provides the precise positioning of object during robotic micro assembly. By developing a prototype, it is demonstrated that compliant piezoelectric micro grippers are capable of handling different objects and simultaneously attempt the multiple robotic micro assembly in a large work space.

Studies on effect of pitch and roll variations on quadrotors's thrust generated

In the recent past, Micro Aerial Vehicles (MAV) have gained a lot of interest among researchers due to the innovations in low-power processors and miniature sensors which in turn opened new horizons in terms of miniaturization and its field of application. MAVs are capable of flying in complex or cluttered environments that make office buildings and commercial centers among many other areas possible for aerial surveillance. MAV can also serve in search-and-rescue missions after earthquakes, explosions, etc. An aerial robot capable of flying through narrow spaces and collapsed buildings could quickly and systematically search victims of accidents or natural disasters without risking human lives. When flying in such conditions, it is essential to have a vehicle that can easily fit through small openings and maneuver around pillars and destructed wall structure. To complete the given tasks effectively and in given time is the biggest challenge in designing any such vehicles. In this paper our approach is mainly to design the MAV which will give desired thrust with given set of rotating blade mechanism. In brief, a kinematic model of the arrangement of MAV is studied keeping in view different aspects like thrust forces, lift coefficient, basic maneuvering operations, etc. Ultimate aim is to generate sufficient thrust to effectively maneuver the MAV.