Electromyogram (EMG) signals can be measured from human muscles and can be used to anticipate movements. In fact, many researchers have tried to use these signals as an interface tool for a prosthetic hand. However, most of these studies focused on the discrimination performance of the EMG signals, and only discussed the control method for the prosthetic hand. Evaluation of the operating performance while the operator wore the prosthetic hand was seldom reported. This paper proposes a virtual prosthetic control system and presents the analyses of a grasp motion under two different EMG control methods: ON-OFF Digital Control (Digital) and Dynamic Mode Control (DMC). DMC is able to proportionally control the grasping velocity based on the amplitude of the EMG signal. Digital controls the hand at a uniform rate while the amplitude of the EMG signal is greater than a predefined threshold. We conducted experiments with five subjects, and confirmed the usefulness of the developed system.

Discusses the multiple active antenna that is simply composed of two insensitive flexible beams placed in the rotational plane, one actuator, one position sensor and one axis moment sensor. The sensor system can detect the contact point between the beams and an object through a simple rotating motion even for the object placed with an inclination angle. During rotating motion, one beam first makes contact with an object. By continuously applying the rotating motion, the second beam makes contact with the same point of the object. Each contact angle is estimated by utilizing both the moment and position sensors. Finally, the contact point can be estimated by the geometrical relationship. The basic idea is verified by experiments.

A dynamic model of a flexible beam in contact with the environment is considered in this paper. The model serves as a background for a dynamic, active antenna type, contact point sensor. In its simplest realization the sensor can be implemented in the form of a flexible beam rotating in plane. The dynamic model is developed in the nondimensional form and possible sensing strategies, active and passive, are outlined. The main feature of the sensor is the use of the frequency-versus contact point curve which, for some regions, may be a multi-valued function. Basic properties of the sensing curves are formulated, and two points of interest-the point of maximal stiffness and the point of center of impact-are introduced into the analysis. Behaviour of the sensing curves is analyzed with respect to three system parameters-mass, inertia, and stiffness ratios. It is found that in some limiting, but practically attainable cases the sensing curve becomes a single-valued function within the working range of the sensor.

Proposes the self-excited dynamic active antenna (SDAA) that can detect a contact location between an insensitive flexible beam and an object through observation of the fundamental natural frequency of the beam in contact with the object. The main, part of SDAA is composed of a flexible beam, one permanent magnet and two electromagnets not only for producing the exciting motion but also for changing the boundary condition of the beam. We show that the contact position is uniquely determined by utilizing the fundamental natural frequencies before and after changing the boundary condition. We present the basic working principle of SDAA and show some experimental results to verify the idea.

A dynamic active antenna sensor for locating a contact point is considered in this paper. In its simplest realization the sensor can be implemented in the form of a flexible beam rotating in plane. The main feature of the sensor is the use of the frequency-contact point curve which, for some regions, may be a multivalued function. One way of "improving" the curve could be concerned with the nonuniform mass and stiffness distribution of the beam which would lead to a rather complicated sensor design. Another way to remedy the situation is to change the sensing strategy by adding a proper control action at the joint of the beam. To study the sensor's response to the control, a dynamic model of the beam in contact with the external environment is developed. Analysis of the frequency equation shows how a simple proportional control law changes the sensing curve. It is found that in some limiting, but practically attainable cases the sensing curve becomes a single-valued function. Thus, the solution proposed can significantly simplify the identification procedure.

This paper discusses theoretical and experimental investigation, on dynamic active antenna which can detect the contact point between an insensitive flexible beam and an object through estimation of the oscillation frequency in contact with the object. We first prove that the contact position is uniquely determined if we consider every mode of natural frequencies of the beam in contact with the object, while the fundamental and the second order natural frequency, in most cases, satisfy the sufficient condition for providing the unique contact position. We also show a desirable mass distribution avoiding the estimation error for localizing the contact position. By utilising the maximum entropy method, we succeeded in experimental estimating the contact point from the fundamental and the second order natural frequencies.

This paper discusses a new sensing strategy for the dynamic active antenna which can detect the contact point between an insensitive flexible beam and an object through the estimation of the oscillation frequency in contact with the object. The strategy is composed of two steps. In the first step, the fundamental and the second order natural frequencies of the beam in contact with the object are evaluated by utilizing an extended Kalman filter. Then by using the mapping diagram from those two frequencies into the contact point, we can uniquely obtain the contact point. We show that the use of the fundamental and the second order natural frequencies is sufficient for localizing the contact point.

This paper discusses a dynamic active sensing system, capable of detecting the contact point between a flexible beam and an object. The proposed sensing system is simply composed of an insensitive flexible beam, a torque sensor, a joint position sensor, and an actuator. The dynamics (such as moment of inertia and stiffness) of the sensing system changes when the motion phase switches from non-contact to contact. We show that the natural frequency during contact is generally a multi-valued function of the contact location, which is not desirable from the viewpoint of determining the contact location uniquely. It is also shown that by adding a proper mass at the free end of the beam, we can make the function close to a single-valued one. The additional mass also contributes to reducing the oscillation frequency, which releases us from treating high frequency signals. We design the hardware model based on this idea, and verify the basic principle experimentally.>

This paper addresses a new active sensor system (Active Antenna) motivated by insect's antenna. The antenna can be characterized by its "flexibility" and "active motions". Based on these observations on insect's antenna, the authors' discuss an active sensor system composing of only four components, an insensitive flexible antenna, a position sensor, a torque sensor, and an actuator. The authors first consider the conditions which allow localisation of any contact point between the insensitive flexible antenna and environment by applying an active motion to the antenna. The authors show that the use of a straight antenna always makes it possible to localise the contact point irrespective of friction at the point of contact. The authors also show that contact point sensing by the use of a circular shaped antenna is weakly influenced by the friction at the point of contact.>