Advanced Robotics

Okadome, Yuya; Nakamura, Yutaka; Ishiguro, Hiroshi

doi: 10.1080/01691864.2014.894607pmid: N/A

A bio-inspired robot with many degrees of freedom (DOFs) might be beneficial in coping with various situations that occur in a real environment, because its physical structure resembles that of an animal it is modeled after. However, because of its complicated structure, it is difficult to explicitly model the dynamics and to design the control rules. In this study, we propose a predictive control method based on a non-parametric method. Instead of conducting parameter estimation for a certain parametric model, system identification is performed by collecting data. We apply our method to the control of a robot with a complicated structure. Experimental results show that the control of a robot with many DOFs can be achieved by the proposed method.

Hodgson, Sean; Tavakoli, Mahdi; Lelevé, Arnaud; Pham, Minh Tu

doi: 10.1080/01691864.2014.888130pmid: N/A

For a pneumatic teleoperation system with on/off solenoid valves, sliding mode control laws for position and force ensuring low switching (open/close) activity of the valves are developed. Since each pneumatic actuator has two pneumatic chambers with a total of four on/off valves, 16 possible combinations (‘operating modes’) for the valves’ on/off positions exist, but only seven of which are both functional and unique. While previous work has focused on three-mode sliding-based position control of one pneumatic actuator, this paper develops the seven-mode sliding-based bilateral control of a teleoperation system comprising a pair of pneumatic actuators. The proposed bilateral sliding control schemes are experimentally validated on a pair of actuators utilizing position-position and force-position teleoperation architectures. The results demonstrate that leveraging the additional modes of operation leads to more efficient and smoother control of the pneumatic teleoperation system. It was found that viscous friction forces were crippling haptic feedback in the position-position architecture. Through the use of force sensors, the force-position architecture was able to compensate for the heavy viscous friction forces.

Bi, Shusheng; Niu, Chuanmeng; Cai, Yueri; Zhang, Lige; Zhang, Houxiang

doi: 10.1080/01691864.2014.888373pmid: N/A

This study aims to develop a waypoint-tracking control system for a biomimetic underwater vehicle (BUV). The BUV is propelled by wide paired pectoral foils, and each pectoral foil is driven by three independent fin rays. To simplify the control strategy, the maximum flapping amplitude of the pectoral fin is used to control the forward velocity, and a turning factor is defined for the manoeuvre control. Several swimming experiments are carried out to investigate the influence of the control parameters on the swimming performance of the prototype. Based on the results of the swimming experiments, a waypoint-tracking control system is proposed, which contains two layers: the velocity control layer and the heading angle control layer. A subdivision control method is adopted by the velocity control layer to get the maximum flapping amplitude. The fuzzy control method is employed by the heading angle control layer to obtain the turning factor for steering motion. Several waypoint-tracking experiments are carried out to verify effectiveness of the control system. The results show that the prototype can automatically reach the target area with the designed control system, even though the waypoints are arranged or randomly given.

Ottaviano, Erika; Rea, Pierluigi; Castelli, Gianni

doi: 10.1080/01691864.2014.891949pmid: N/A

In this paper, the design, simulation and experimental tests are presented for THROO: a Tracked Hybrid Rover, which has been developed to Overpass Obstacles. The proposed mobile robot has 3-DOFs and it is capable of straight motion, turning ability and two operations, namely rover-like motion with tracks on flat terrain and walking-like motion with track and legs to overpass obstacles to move on uneven terrain. The leg mechanism is composed of a four-bar linkage, which has been synthesized according to the desired features. In particular, the Burmester problem, which aims at finding the geometric parameters of a four-bar linkage required for a prescribed set of finitely separated poses are solved for the case understudy. Dynamic simulations have been carried out and a prototype has been built. The proposed results show the hybrid rover ability to overpass obstacles, for which size is comparable or greater than the track high.

Mashayekhi, Ahmad; Boozarjomehry, Ramin B.; Nahvi, Ali; Meghdari, Ali; Asgari, Pouya

doi: 10.1080/01691864.2014.894940pmid: N/A

In this paper, a new criterion for passivity of haptic devices is obtained. This criterion creates a relationship between Coulomb friction coefficient, viscous friction coefficient, sampling rate, and the maximum simulated stiffness. The process of derivation of the passivity criterion is described in detail. This criterion is improved compared with other existing criteria and predicts passivity in haptic rendering more accurately. In particular, for speeds of less than 5 cm/s, the new passivity criterion should replace the previous criteria to avoid unwanted vibrations of stiff virtual walls. Analytical and numerical investigations are presented to validate the new criterion. A specific trajectory is designed and the movement of the haptic robot is investigated on this trajectory to validate and compare this passivity criterion with the previous criteria.

Zhang, Jifeng; Chen, Qiaohong; Wu, Chuanyu; Li, Qinchuan

doi: 10.1080/01691864.2014.888374pmid: N/A

Two types of kinematic calibration method for a 2-DOF (degrees of freedom) translational parallel manipulator are proposed using different error models. A calibration experiment is performed on both methods using an Absolute Laser Tracker and the results are compared. Two error models of the 2-DOF translational parallel manipulator are established using differential method and linear perturbation method, respectively. The two error models are solved using both the least squares method and linear equations. The results for the two different calibration methods show that the error model based on differential method is more effective in improving the accuracy of the 2-DOF translational parallel manipulator. Overall, the absolute position error of the 2-DOF translational parallel manipulator is significantly reduced to 0.13 mm from 0.93 mm after kinematic calibration.