Erhan Ilhan Konukseven

Evaluation of haptic feedback cues on vehicle teleoperation performance in an obstacle avoidance scenario

Teleoperation of an unmanned vehicle is a challenging task for human operators especially when the vehicle is not within line of sight. Lack of situational awareness and increased workload due to limited perception channels result in degraded task performance. If these teleoperation missions are human-critical then it becomes more important to improve the operator performance by decreasing workload and improving situational awareness. In this paper, a new teleoperation interface which provides force feedback based on the path generated by an obstacle avoidance algorithm is presented. The purpose of this interface is to overcome the difficulties imposed by limited field of view and lack of situational awareness. Teleoperation tests are performed to verify that haptic feedback generated from the dynamic obstacle information of the environment improves teleoperation performance by supporting the operator and decreasing the workload.

Product Based Material Testing for Hyperelastic Suspension Jounce Bumper Design with FEA

The basic problem in the finite element analysis of parts made of hyperelastic materials is the identification of mathematical material model coefficients. Furthermore, selection of a suitable mathematical hyperelastic material model may not be straightforward. In this study, a systematic design methodology is presented for hyperelastic suspension jounce bumpers. The presented methodology involves a critical examination of material testing procedures, material model selection, and coefficient identification. The identified material model coefficients are verified through comparison of the finite element analysis results with actual tests.

i-RoK: A human like robotic head

In order to explore issues of human-robot interaction in a social context, we have constructed a humanoid robotic head called i-RoK. This paper focuses on the study and design of the anthropomorphic head robot developed at the Mechanical Engineering Department of Middle East Technical University. The robot has a total of 8 mechanical degrees of freedom. This allows the robot to mimic the same movements performed by human head. We discuss major design issues of the developmental head and the design characteristics of the robot, i-RoK, in this paper.

New parameter estimation method of linear adaptive filter for modeling kinematic motion primitive of effective DOF of hand

In this paper, We have extracted and modeled the motion primitive of human hand in a simple 1-DOF rhythmic motion task, i.e. manipulating mass-spring-damper system. The experiment was carried out by using 1-DOF haptic box with virtual reality in Simulink environment. The interaction dynamics of haptic box and human which consists of hand and brain reveals the role of the human as an intelligent admittance. We tested 6 people who tried to combine motion primitives to produce smoother motion during learning process. In addition, we developed a novel identification method for modeling the rhythmic motion of hand in model space. It is shown that adaptive filter as a predictor of motion primitives with two parameters and two initial values appears as an ellipse in model space. The geometrical properties of ellipse are related to the parameters and initial values of adaptive filter that make it possible to identify the parameters of adaptive filter in model space.

Kinematic Calibration of PHANTOM Premium 1.5/6DOF Haptic Device

Precise positioning and precise force control requirement in haptic devices necessitate the calibration of the device. Since force control algorithms in haptic interfaces employ Jacobian matrix that includes kinematic model parameters, calibration is not only important for pose accuracy but also for force control. The deviation in kinematic parameters and joint transmission errors are main reasons disturbing the calibration of the haptic devices. Capstan drives and parallelogram mechanisms are preferred to use for actuation in haptic device design. Their transmission errors should be estimated in the calibration. This paper presents a simulation study including the estimation of kinematic parameters and transmission errors due to the capstan drives and parallelogram mechanism for a PHANTOM Premium haptic device.

A Novel Rotary Magneto-Rheological Damper for Haptic Interfaces

Haptic interfaces require lightweight, small actuators with high force capability and low friction. In this paper, based on the structure of conventional shear mode disc and drum type MR fluid dampers, a lightweight continuous rotary MR damper working in valve mode is designed for haptic interfaces. The proposed design is compared to shear mode disc-type and drum-type designs with similar torque–to–mass ratio via computer simulations. Mathematical models for the resistant torques of both the shear mode and the valve mode are derived. Subsequently, the finite element analysis of electromagnetic circuit calculations was carried out by FEMM software to perform an optimization of the dimensions of the parts such as gap size and thickness. It is shown that the proposed continuous rotary valve mode MR damper is a fine candidate that meets the requirements of haptic interfaces.Copyright

Self-learning road detection with stereo vision

It is a hard to solve problem to detect traversable or road regions especially in unstructured roads or paths. In mobile robot applications, robots usually enter these kinds of roads and regions. To successfully complete its mission, it is important to find roads in these environments reliably. In this paper a novel unstructured road detection algorithm with the capability of learning road regions continuously is proposed.

Theoretical and Experimental Determination of Dynamic Friction Coefficient for a Cable-Drum System

Cable-drum systems are utilized to convert the rotary motion of a drum into a translational motion of a linear stage connected to the cable. These systems are preferred where low backlash and high stiffness is expected. They are commonly employed in machines like elevators, photocopy machines, printers, plotters etc. For machines having long working ranges, cable-drum systems employing a high resolution encoder offers a practical low cost alternative in position sensing. In most traditional machines and equipments, to get linear position information; potentiometers, linear encoders, laser range finders etc. are commonly used. However, these alternatives are expensive and their installation is not straight forward. Cable-drum systems are not problem free either. The problem coming from using cable-drum system as a linear position sensor grows out of dynamic friction. In this study, the change in the dynamic friction coefficient of the cabledrum system is modeled by using Euler and LuGre friction approaches. In order to see the change of the friction values, the developed model is simulated. To verify of the theoretical results, an experimental set-up is constructed. Both results are presented. It is concluded that for better positioning control change in dynamic friction coefficient during the motion should be accounted for.

Realization of human gait in virtual fluid environment on a robotic gait trainer for therapeutic purposes

Abstract Patients with disorders such as spinal cord injury, cerebral palsy and stroke can perform full gait when assisted, which progressively helps them regain the ability to walk. A very common way to create assistive effects is aquatic therapy. Aquatic environment also creates resistive effects desired for strength building. In this study, realization of a virtual fluid environment on a robotic gait trainer is presented as an alternative method. A model was created to determine torques and forces acting on the human body while performing gait in a fluid environment. The developed model was implemented on a robotic gait trainer. By adjusting the virtual fluid model parameters, precise control over assistive and resistive effects during gait was achieved without enforcing any pre-defined gait pattern. The real-time gait phase information required by the fluid model to determine torques was provided with a developed algorithm which only uses kinematic gait data. Experiments with healthy subjects were done using the robotic gait trainer to verify the gait phase algorithm, and to compare gait characteristics obtained in virtual land and water environments with the literature. Additional experiments were performed with the robotic system to assess effects of changing fluid model parameters to healthy subject ga it characteristics. The results show that force and torque effects of virtual fluid environment on robotic gait trainer were achieved. The gait phase algorithm was shown to provide smooth transition between phases. Also, significant changes in gait characteristics were observed by modifying fluid model parameters.

An adaptive approach for road boundary detection using 2D LIDAR sensor

Robotic ground vehicles are commonly used in various road conditions for performing special tasks with different levels of autonomy. This requires the robots to possess a certain degree of perception about the road conditions up ahead and make plans accordingly. It is essential for the robots to be able to quickly adapt their perception for various road conditions they operate. In this paper, an adaptive method for road boundary extraction using 2D LIDAR sensor is presented. A three-stage detection algorithm is utilized for road determination, in which parameter sets are updated adaptively based on a discriminative learning approach. Details of both the learning approach and the detection algorithm are discussed in detail. Experiments were performed on constructed and unconstructed roads to evaluate the performance of the proposed method, and the outcomes were presented in the paper. The results showed that accuracy of road boundary detection increased significantly with the proposed adaptive method. Likewise, significant changes were observed in the required computational times.