Many recent developments of surgical robots focus on less invasive paradigms, such as laparoscopic SPA (Single Port Access) surgery, NOTES (Natural Orifice Translumenal Endoscopic Surgery), laryngoscopic MIS (Minimally Invasive Surgery), etc. A configuration similarity shared by these surgical robots is that two or more manipulators are inserted through one access port (a laparoscope, an endoscope, or a laryngoscope) for surgical interventions. However, upon designing such a surgical robot, the structure of the inserted manipulators has not been thoroughly explored based on evaluation of their performances. This paper presents a comparison for kinematic performances among three different continuum manipulators. They all could be applied in the aforementioned surgical robots. The structural parameters of these continuum manipulators are firstly optimized to assure a more fair and consistent comparison. This study is conducted in a dimensionless manner and provides scalable results for a wide spectrum of continuum manipulator designs as long as their segments have a constant curvature. The results could serve as a design reference for future developments of surgical robots which use one access port and continuum mechanisms.

In this paper, an optimal fuzzy sliding mode controller has been designed for controlling the end-effector position in the task space. In the proposed control, feedback linearization method, sliding mode control, first-order fuzzy TSK system and optimization algorithm are utilized. In the proposed controller, a novel heuristic algorithm namely self-adaptive modified bat algorithm (SAMBA) is employed. To achieve an optimal performance, the parameters of the proposed controller as well as the input membership functions are optimized by SAMBA simultaneously. In this method, the bounds of structural and non-structural uncertainties are reduced by using feedback linearization method, and to overcome the remaining uncertainties, sliding mode control is employed. Mathematical proof demonstrates that the closed loop system with the proposed control has global asymptotic stability. The presence of sliding mode control gives rise to the adverse phenomenon of chattering in the end-effector position tracking in the task space. Subsequently, to prevent the occurrence of chattering in control input, a first-order TSK fuzzy approximator is utilized. Finally, to determine the fuzzy sliding mode controller coefficients, the optimization algorithm of Self-Adaptive Modified Bat is employed. To investigate the performance of the proposed control, a two-degree-of-freedom manipulator is used as a case study. The simulation results indicate the favorable performance of the proposed method.

This paper proposes control algorithms for heterogeneous teleoperation systems to guarantee stability and tracking performance in the presence of time-varying communication delays. Because robotic manipulators, in most applications of bilateral teleoperation systems, interact with a human operator and remote environment on the end-effector, the control system is developed in the task-space. When the dynamic parameters of the robots are unknown and the communication network is subject to time-varying delay, the developed controller can ensure stability and task-space position tracking. Additionally, if the robotic systems are influenced by human and environmental forces, the presented teleoperation control system is demonstrated to be stable and all signals are proven to be ultimately bounded. By employing the redundancy of the slave robot for sub-task control, the proposed teleoperation system can autonomously achieve additional missions in the remote environment. Numerical examples utilizing a redundant planar robot are addressed to validate the proposed task-space teleoperators with time-varying delay.

In this paper, an analytical formula for the determination of the center of mass position in humanoid platforms is proposed and tested in a real humanoid robot. The formula uses the force-torque values obtained by the two force-torque sensors applied on the feet of the robot and the measured currents required from the motors to maintain balance as inputs. The proposed formula outputs the real center of mass position that minimizes the errors between real humanoid robots and virtual models. Data related to the Zero Moment Point positions and to the joint movements are compared with the target values, showing how the application of the proposed formula enables achieving better repeatability and predictability of the static and dynamic robot behaviour.

In this paper, a pseudoinverse-type bi-criteria minimization scheme is proposed and investigated for the redundancy resolution of robot manipulators at the joint-acceleration level. Such a bi-criteria minimization scheme combines the weighted minimum acceleration norm solution and the minimum velocity norm solution via a weighting factor. The resultant bi-criteria minimization scheme, formulated as the pseudoinverse-type solution, not only avoids the high joint-velocity and joint-acceleration phenomena but also causes the joint velocity to be near zero at the end of motion. Computer simulation results based on a 4-Degree-of-Freedom planar robot manipulator comprising revolute joints further verify the efficacy and flexibility of the proposed bi-criteria minimization scheme on robotic redundancy resolution.

In this paper, a novel 3(RPSP)-S fully spherical parallel manipulator (SPM) is introduced. Also, an innovative method based on the geometry of the manipulator is presented for solving the forward position problem of the manipulator. The presented method provides a framework for the future research to solve the forward position problem of the other fully spherical PMs (for examples 3(UPS)-S and 3(RSS)-S). In the proposed method, two coupled trigonometric equations are obtained by utilizing the geometry of the manipulator and Rodrigues' rotation formula. Using Bezout's elimination technique, the two coupled equations lead to a polynomial of degree eight. We show that the polynomial is minimal and optimal. Furthermore, the other method is proposed for selecting an admissible solution of the forward position problem. This algorithm is required to control modeling and dynamic simulations.

Using simple running models, researchers have argued that swing-leg retraction can improve running robot performance. In this paper, we investigate whether this holds for a more realistic simulation model validated against a physical running robot. We find that swing-leg retraction can improve stability and disturbance rejection. Alternatively, swing-leg retraction can simultaneously reduce touchdown forces, slipping likelihood, and impact energy losses. Surprisingly, swing-leg retraction barely affected net energetic efficiency. The retraction rates at which these effects are the greatest are strongly model-dependent, suggesting that robot designers cannot always rely on simplified models to accurately predict such complex behaviors.

The flexible robotic drilling system has been widely used in the aircraft industry in recent years. There are three ways to attach an end-effector to a robot, which are the pointing configuration, the hanging configuration, and the side configuration. The simulation model of robot and workpiece is constructed by using MATLAB software. According to the three configurations, reachability, manipulability, joint useability, and joint passive torque of a robot are calculated by means of the MATLAB language. Based on the calculation results and various measures, the performance, including reachability, manipulability, joint useability, and deformation, of a robot are analyzed. The analysis results show that the pointing configuration has the best reachability, a long service life, and small energy consumption, and it substantially reduces the fifth axis joint passive torque produced by the clamp force, which will improve positional accuracy of holes; the hanging configuration and the side configuration improve robot's manipulability and are suitable for drilling in the curved surface.

This paper describes and evaluates the use of a head-mounted display (HMD) for the teleoperation of a field robot. The HMD presents a pair of video streams to the operator (one to each eye) originating from a pair of stereo cameras located on the front of the robot, thus providing him/her with a sense of depth (stereopsis). A tracker on the HMD captures 3-DOF head orientation data which is then used for adjusting the camera orientation by moving the robot and/or the camera position accordingly, and rotating the displayed images to compensate for the operator's head rotation. This approach was implemented in a search and rescue robot (RAPOSA), and it was empirically validated in a series of short user studies. This evaluation involved four experiments covering two-dimensional perception, depth perception, scene perception, and performing a search and rescue task in a controlled scenario. The stereoscopic display and head tracking are shown to afford a number of performance benefits. However, one experiment also revealed that controlling robot orientation with yaw input from the head tracker negatively influenced task completion time. A possible explanation is a mismatch between the abilities of the robot and the human operator. This aside, the studies indicated that the use of an HMD to create a stereoscopic visualization of the camera feeds from a mobile robot enhanced the perception of cues in a static three-dimensional environment and also that such benefits transferred to simulated field scenarios in the form of enhanced task completion times.

This paper is a continuation of a previous work of authors, Scaglia et al. [G. J. E. Scaglia, L. M. Quintero, V. Mut and F. Di Sciascio, “Numerical methods based controller design for mobile robots,” Robotica27(2), 269–279 (2009)]. A method is presented to choose the controller parameters such that, the values of the control actions do not exceed the maximum allowable and the tracking errors tend to zero. In addition, the analysis of the controller design parameters is included. The experimental results (laboratory experiments and a real world application) demonstrate the efficiency of the controller.

Studying wheel and ground interaction during motion has the potential to increase the performance of localization, navigation, and trajectory tracking control of a mobile robot. In this paper, a differential mobile robot is modeled in a way that (traction, rolling, and lateral) wheel forces are included in the overall system dynamics. Lateral wheel forces are included in the mathematical model together with traction and rolling forces. A least square parameter estimation process is proposed to estimate the parameters of the wheel forces. In order to implement the proposed methodologies, an experimental setup is used. The setup contains a differentially driven mobile robot, a specially constructed test surface, and a camera system attached at the top of surface for obtaining ground truth. Models having one or more wheel forces are simulated to find the most realistic model. Simulation results are verified by experiments.