Whisker Sensor Research Articles

Realization of Contact Surface Geometry by Dragging a Whisker-type Tactile Sensor Across Measuring Objects

Previously we reported a method for displaying the shape of an object by using an array of whisker sensors. The array of whiskers was pressed against the object to be measured and the deflection of each whisker was measured. The measurements were used as inputs to a neural network to recognize the shapes. However, the previous method needed a larger number of whiskers to recognize the wider surface, because the array of whiskers has to be in full contact with the entire surface. Therefore, this study presents a new method in which a much smaller number of whiskers are dragged across the surface of the measured object to distinguish the shapes. The method is performed in the following manner. Firstly, a smaller number of whiskers are dragged across an object and each whisker deflection direction is distinguished at discrete time intervals. Next, the neural network continuously monitors the output from the whiskers and produces a result that characterizes the surface at the current scan position. Lastly, by building up a map of the classification of the entire surface, the geometry of the measured object can be displayed. This study exhibits the hardware and software required for displaying shapes, and shows examples of the results obtained from the measurements of some objects.

Recognising and manipulating objects using data from a whisker sensor array

For many biological creatures sensory whiskers are an effective means of detecting and recognising nearby objects. The project described in this paper has the aim of demonstrating that whisker sensors can be used as a similarly effective form of robot sensing. Many mobile robots have used whiskers as simple switches to warn of an imminent collision. However, these devices cannot provide the detailed surface profile information required to recognise and accurately locate objects. Several research groups have built advanced whisker sensors that can determine the position of a contact along the length of the whisker. Although these whisker sensors are usually little more than a length of flexible spring material they do require complex sensing and actuation mechanisms at the whisker root. In this project an array of eight whisker sensors is scanned over external objects by the motion of the robot. The resulting deflection of the whiskers is monitored by a potentiometer at each whisker root. By recording the deflection of the whiskers as they slide over external objects sequences of surface points can be determined. Object recognition algorithms have been developed that allow the robot to recognise, grasp and retrieve a range of objects using the whisker data. In this paper the robot, WhiskerBOT, is described together with the object recognition and localisation algorithms. Results of practical experiments are also presented.

Frequency Discriminated Plural Whisker Sensor.

This paper discusses the whisker sensor that can detect the surface features through a tracing motion. The sensor is composed of plural number of flexible beams with different natural frequencies, an adapter with strain gauge for each whisker, and an actuator for moving all of them. The mechanical vibration coming from the surface irregularities are picked up by each whisker and then converted into electrical signals through strain gauges. From the viewpoint of reducing the signal lines and cost, we feed all signals into one amplifier by connecting each strain gauge serially in the gauge box. Through the analysis of power spectrum, we estimate where the vibration comes from and how much irregularity is. We show the basic working principle of the sensor and experimental results to verify the idea.

Force Sensing Unit with Single Amplifier and an Application to a Whisker Sensor

In this paper, uniaxial force sensor unit with single amplifier is developed. Four strain gauges attached to thin elastic plate constitute a bridge circuit which counts normal component of acting force automatically. It is easy to implant a uniaxial moment sensor in the unit independently. As an application of developed sensor unit, a whisker sensor system, which is simply composed of a flexible tactile beam and two force/moment sensor units, is proposed. The system is able to detect contact location between the flexible beam and an object. Contact force when the beam makes contact at its tip end is experimentally examined.

A Whisker Tracing Sensor for Manufacturing Application

This paper discusses a whisker sensor composed of a flexible beam anchored at the base with torque sensor, and an actuator for moving it. A sufficient condition for detecting the surface shape by using a whisker sensor is summarized. It is shown that a straight-lined whisker sensor with one axis torque sensor can achieve the requirement irrespective of contact friction, while a curved whisker can not do it. We show an application example where the sensor is utilized for detecting the effective length of screw after tapping.

The whisker sensor and the transmission of multiple sensor signals

First, a new type of proximity sensor called a 'whisker sensor' is proposed which consists of an elastic whisker and a sensing system mounted at the base of the whisker. The sensing device detects any minute flexure of the whisker when it touches an object during motion of the robot. The recommended material for the wisker is a TiNi shape memory alloy with pseudo-elasticity. For signal detection, both the so-called bit- and analogue-type detectors are shown to be realizable. The bit-type whisker sensor can be constructed in a compact form with a simple and solid mechanism so that it is economical, can be used in a dangerous environment, and as many as necessary can be mounted on the robot. The analogue-type whisker sensor, based on a photo-interrupter for the sensing system, has been experimentally assembled and its capability for detecting objects with a good degree of accuracy is demonstrated. Second, the importance of installing multiple tactile or proximity sensors on a robot, as in insects or mammals...

Gas sensing characteristics of tin oxide whiskers

An attempt was made to use tin oxide whiskers as gas sensor materials. The whiskers were prepared mainly by oxidation of metallic tin at 1100 °C under low partial pressure of oxygen. The electrical conductance of the whisker sensors was relatively small, but they showed substantial changes in conductance when exposed to inflammable gases. The sensitivity was dependent on the whisker thickness; in general, the thinner the whisker, the higher the sensitivity. However, with whiskers thinner than about 5 μm the sensitivity decreased. Sb 5+ -doping and addition of Pd did not enhance the sensitivity. A mechanism of gas detection was proposed based on changes in a positively charged space layer near the surface.