Atsutoshi Ikeda

Weight and friction display device by controlling the slip condition of a fingertip

In this paper, we propose a novel haptic device that gives weight and friction illusions. Sensing a slip condition at a fingertip plays an important role to estimate the weight and friction properties of an object. This fact suggests that controlling the contact condition could yield weight and friction illusions. Based on this idea, a prototype device was developed that controls the contact surface between a fingertip and a rigid plate based on a camera-based eccentricity control. The desired eccentricity profile was given from the mathematical relationship between the eccentricity and the surface deformation, which is obtained by known material parameters, vertical/lateral forces applied on the contact area, and static friction coefficient. The performance of the developed device was evaluated through human experiments. The experimental results show the statistically significant difference between presented weight and friction conditions.

NAIST hand 2: Human-sized anthropomorphic robot hand with detachable mechanism at the wrist

Humanoid robots and robotic manipulators with good dexterity are promising to enhance the factory productivity in next generation. Dexterity of robotic manipulators can be achieved by equipping an anthropomorphic robot hand with multiple fingers. Additionally, in order to manipulate various tools that humans are using in daily life, the size and the exerting force of the robot hand should be similar to that humans are. In this paper, we proposed a human-sized multi-fingered robot hand with detachable mechanism at the wrist. The robot hand can be split at the wrist into the hand part and the actuator part. The fingers are driven by wires and are controlled by actuators embedded in the arm part. The driving force from the arm part is transmitted to the hand part by gear mechanism at the wrist. The developed robot hand has the size of 200[mm](length) × 78[mm](width) × 24.6[mm](thickness) and can exert 10[N] at the fingertip. The performance of the developed robot hand was shown by a motion control experiment.

Haptic augmented reality interface using the real force response of an object

This paper presents the haptic interface system that consists of a base object and a haptic device. The desired force response is achieved by the combination of the real force response of the base object and the virtual force exerted by the haptic device. The proposed haptic augmented reality (AR) system can easily generate the force response of a visco-elastic object with a cheap haptic device and a base object that has the similar visco-elastic property to the target object. In the demonstration, the force response of the target object was generated by using a haptic device only (VR) and using both a haptic device and a base object (AR), respectively. The evaluation experiments by participants show that the AR method has better performance than the VR method. This result indicates the potential of the proposed haptic AR interface.

Remote control system for multiple mobile robots using touch panel interface and autonomous mobility

Moving to the location designated by the user is the most fundamental task for a mobile robot. Remote control is one of the effective solutions to navigate the robot to the target location, but the user suffers from the burden to continuously concentrate on the remote control. As the result, several users are required in accordance with the number of robots to operate. In this paper, we propose the remote control system that uses touch panel interface, simultaneous localization and mapping (SLAM), and motion planning to achieve autonomy of mobile robots. To navigate the robot in the proposed system, the user only designates the destination and via-points by touching on the map estimated by the SLAM. After receiving the users input, the Rapidly-exploring Random Tree (RRT) generates the feasible path to the destination using the estimated map. The effectiveness of the proposed system is verified through experiments where multiple mobile robots are remotely controlled.

A tendon skeletal finger model for evaluation of pinching effort

In this paper, we propose a tendon skeletal finger model and discuss which finger postures the human feels easy to pinch based on the tendon forces and the human experimental results. The finger model mimics a human tendon skeletal structure. The tendon forces during the pinching motion were simulated using the finger model. Simulation results show that the tendon forces closely mirror the human muscle activity. Sensory evaluation of subjective pinching effort was conducted with five subjects. The subject pinched five kinds of cylinders, from 20 [mm] to 100 [mm]. The pinching force and the surface EMGs were simultaneously measured in the experiment. Based on the human questionnaire tests, we investigated which finger postures the human feels easy to pinch a cylinder. The results show that the pattern of the EMGs measured by the experiment is very similar to that of the tendon forces calculated by the finger model simulation. This indicates that the tendon force is a useful index of the subjective pinching effort and it can be used for the quantitative evaluation instead of EMGs.

Biomechanical analysis of subjective pinching effort based on tendon-skeletal model

In this paper, the influence of the finger posture on the subjective effort during pinching motion is investigated by using a tendon-skeletal finger model. The experimental results show that the subjective effort human feels is affected by the size of the object he/she pinches, and the subjective effort correlates with the finger length. The simulation results show that the pattern of the tendon forces is similar to that of the EMG activity measured in the experiment, and the positive correlation was observed between the finger length and the object size where the summation of the tendon forces becomes the minimum. These results suggest that the reason why subjective pinching effort is influenced by the finger posture is the difference in the efficiency of the force transmission from the muscles.

Producing Method of Softness Sensation by Device Vibration

In this paper, we propose a producing method of softness sensation using device vibration. The basic idea of the softness producing method is to provide a softness illusion of stimulating cutaneous mechanoreceptor by vibration. A prototype device is developed to verify effect of parameters of the vibration: frequency, amplitude and wave shape, on softness sensation. We create a database which indicates relationship between softness sensation and the vibration parameters to control the prototype device. Then subjective experiment is conducted for validation of the softness producing method. Experimental result shows that the proposing method can be used for softness sensation producing with valid resolution.

Product usability estimation using musculoskeletal model

This paper proposes an estimation method of product usability using a musculoskeletal model. The aim of this study is to estimate product usability based on tendon forces during an object manipulation. First, we explain the estimation method of product usability. The product usability is estimated quantitatively from the tendon forces. The mulculoskeletal model of the index finger and the thumb is constructed to calculate the tendon forces. We call this model the tendon skeletal model. The tendon forces are calculated based on grasping information using a tendon skeletal model. Next, the cylinder pinching simulation using the proposed method is shown. The simulation result is compared with the human experimental result to evaluate the effectiveness of the proposed method. The sensory evaluation of the subjective grasp effort was conducted with five subjects. The calculated score of the simulation reflects the questionnaire survey result by the subjects. As an application, we show the evaluation results of the cell-phone button pushing. The calculated score by the simulation is also compared with the human questionnaire score. These results indicate that the proposed method can be used for the quantitative evaluation of the product usability.

Evaluation of pinching effort by a tendon-driven robot hand

In this paper, we focus on the hand posture when a human subject pinches an object, and the correlation between the results of sensory evaluation by the subject and the tendon force of the subjects fingers are investigated. Surface electromyogram (surface EMG) and pinching force are measured during the pinching motion of human subjects. Experimental results show that subjects feel comfortable pinching a 60 [mm] cylinder. The surface EMGs are lower in the vicinity of 60 [mm]. Furthermore, a tendon-driven robot hand is developed as a sensing hand prototype. The surface EMGs and the motor torque are compared in a pinching experiment using the tendon-driven robot hand. Experimental results show that the tendon-driven robot hand is effective for quantitatively evaluating pinching effort. Simulation of the pinching motion is conducted using a simple finger model. The simulation results show the importance of finger posture and the moment arm in estimating tendon force. Taken together, these results demonstrate the possibility of conducting quantitative evaluation using the tendon-driven robot hand.

Robotic finger perturbation training improves finger postural steadiness and hand dexterity

The purpose of the study was to understand the effect of robotic finger perturbation training on steadiness in finger posture and hand dexterity in healthy young adults. A mobile robotic finger training system was designed to have the functions of high-speed mechanical response, two degrees of freedom, and adjustable loading amplitude and direction. Healthy young adults were assigned to one of the three groups: random perturbation training (RPT), constant force training (CFT), and control. Subjects in RPT and CFT performed steady posture training with their index finger using the robot in different modes: random force in RPT and constant force in CFT. After the 2-week intervention period, fluctuations of the index finger posture decreased only in RPT during steady position-matching tasks with an inertial load. Purdue pegboard test score improved also in RPT only. The relative change in finger postural fluctuations was negatively correlated with the relative change in the number of completed pegs in the pegboard test in RPT. The results indicate that finger posture training with random mechanical perturbations of varying amplitudes and directions of force is effective in improving finger postural steadiness and hand dexterity in healthy young adults.