Pneumatic Linear Bearing Research Articles

Microforce materials tester

A material tester for evaluating the mechanical response of general objects against micro-Newton level impact forces has been proposed. In the tester, an inertial mass is made to collide with the material under test. The impact force acting on the material is measured as the inertial force of the mass. A pneumatic linear bearing is used to realize linear motion with small friction acting on the mass that is the moving part of the bearing. The velocity of the mass is measured highly accurately by means of an optical interferometer. The acceleration, the inertial force, and the position of the mass is numerically calculated from the velocity after the collision measurement. The other force, which is mainly consisted of the friction acting inside the bearing, is determined using the same instrumentations. Using the estimated friction inside the bearing, the measured force is corrected. The force acting on the mass from the material under test of approximately 0.1 mN is measured with the standard uncertainty of approximately 1.4μN.

Method for generating and measuring the micro-Newton level forces

A method for generating and measuring the micro-Newton level forces is proposed. In the method, the force is generated and measured as the inertial force acting on a mass. A pneumatic linear bearing is used to realize a linear motion with sufficiently small friction acting on the mass, i.e. the moving part of the linear bearing. The inertial force acting on the mass is calculated from the velocity of the mass, and the velocity is determined highly accurately by means of measuring the Doppler shift frequency of the laser light beam reflecting on the mass using an optical interferometer. To demonstrate the performance of the method, the mechanical properties of a piece of paper have determined with the resolution of 0.5 μN.

Method for evaluating mechanical response of human skin against micro impact force

Method for evaluating mechanical response of human skin against micro impact force is proposed. The method is a variation of the levitation mass method, which has been proposed and developed by the author. In the method, a mass that is levitated with a pneumatic linear bearing, and hence encounters negligible friction, is made to collide with an object under test, such as a skin of human hand. During the collision the Doppler frequency shift of the laser beam reflecting from the mass is accurately measured using an optical interferometer. The velocity, the position, the acceleration and the inertial force of the mass are calculated from the measured time-varying Doppler frequency shift. The method is characterized by the fact that preparation of the test is very easy and the testing time is very short.

Optical method for evaluating material friction

An optical method for measuring the frictional force acting between general materials is proposed. In the method, the frictional force is measured as the inertial force acting on a mass. A pneumatic linear bearing is used to realize a linear motion with sufficiently small friction acting on the mass, i.e., the moving part of the linear bearing. The inertial force acting on the mass is calculated from the velocity of the mass, and the velocity is determined highly accurately by means of measuring the Doppler shift frequency of the laser light beam reflecting on the mass using an optical interferometer. The performance of the proposed method is demonstrated by means of measuring the frictional force acting between a model car and a metal plate.

Method for evaluating material viscoelasticity

A method for evaluating the viscoelasticity of materials under oscillation load is proposed. In the method, a material under test is connected to a mass, which generates an oscillating inertial force after the mass is manually struck using a hammer. A pneumatic linear bearing is used to realize linear motion with sufficiently small friction acting on the mass that is the moving part of the bearing. The inertial force acting on the mass is determined highly accurately by means of measuring the velocity of the mass using an optical interferometer.

Proposal for a step response evaluation method for force transducers

A method is proposed for evaluating the dynamic response of force transducersto a step force. In the method, gravitational and inertial forces actingon an object, which is suddenly put on a force transducer under test,are used as the reference force. At the beginning of the evaluation, theobject is suspended using a wire just above the transducer. The object isthen made to fall on to the transducer by cutting the wire. To realizeperpendicular motion with sufficiently small friction, a pneumatic linear bearing isused. The inertial force acting on the object is measured highly accuratelyby measuring the velocity of the mass using an optical interferometer.

A method for calibrating force transducers against oscillation force

A method for evaluating the dynamic response of force transducers against anoscillation force is proposed. In the method, a force transducer is connected to amass by a spring, which generates the oscillating force after the mass is manuallyhit using a hammer. A pneumatic linear bearing is used to realize linear motionwith sufficiently small friction acting on the mass, which is the moving part of thebearing. The inertial force acting on the mass is determined highly accuratelyby measuring the velocity of the mass using an optical interferometer.

Measurement of force acting on a moving part of a pneumatic linear bearing

A method for evaluating the components of the force acting on a moving part of a pneumatic linear bearing is proposed. The total force acting on the moving part is accurately measured as the inertial force using an optical interferometer. Then, the components of the force, such as the force component depending on position, the force component depending on velocity, and the force component depending on tilt angle, are evaluated using the least-squares method. In the experiment, the total force acting on the moving part is measured with the standard uncertainty of approximately 0.001 N, which corresponds to approximately 0.003% (30 ppm) of the gravitational force acting on it (M=4.119 kg) of approximately 40 N (40 N). The experimentally evaluated values of these force components well coincide with the theoretically expected values.

Measurement of steep impulse response of a force transducer

Steep impulse responses of a force transducer are measured using a method underdevelopment. In the method, a mass is made to collide with a force transducerand the impulse, i.e., the time integration of the impact force, is measured highlyaccurately as a change in momentum of the mass. A pneumatic linear bearing isused to realize linear motion with sufficiently small friction acting on the mass,i.e., the moving part of the bearing. Steep impulses with the half-value width ofapproximately 1 ms and maximum impact force of up to approximately 1 kN areapplied to a force transducer and its impulse responses are evaluated.

Evaluation of momentum transfer responses of commercial force transducers

Momentum transfer responses of two commercial force transducers are evaluated by means of the developing method based on the law of conservation of momentum. In the method, an object levitated with sufficiently small friction using a pneumatic linear bearing is collided with a force transducer. The inertial force acting on the object is measured as the product of the mass and the acceleration. Approximately 120 sets of collision experiments, whose momentum transfers with the maximum value of approximately 20–120 N with the full width at half maximum (fwhm) of approximately 12–40 ms, have been conducted using two commercial force transducers and two dampers. The instantaneous value of inertial force is measured with the sampling period of approximately 0.15 ms. Its standard uncertainty is approximately 0.9 N, which corresponds to approximately 1% of the maximum applied momentum transfer. The momentum transfers measured by this method and by the transducers coincide within 1% in all the collision measurements.

Measurement of impulse response of force transducers

Impulse responses of force transducers are measured. An object levitated with sufficiently small friction using a pneumatic linear bearing is made to collide with a force transducer under test. The inertial force acting on the object is measured as the product of the mass and the acceleration. The acceleration of the object is measured using an optical interferometer. The output signal of the force transducer and the inertial force acting on the levitated object are then compared. Impulses with a maximum value of approximately 80–90 N with a half value width of approximately 5–19 ms have been applied to two different types of force transducers. The inertial force is measured with standard uncertainty of approximately 0.9 N, which corresponds to approximately 1% of the maximum applied impulse.

F-1028 力センサーの衝撃応答の評価について(G10-4 計測)(G10 機械力学・計測制御部門一般講演)

Impulse response of a force transducer is measured by means of the developing method based on the law of conservation of momentum. In the method, an object levitated with sufficiently small friction using a pneumatic linear bearing is collided with a force transducer. The inertial force acting on the object is measured as the product of the mass and the acceleration. The output signal of the transducer is compared with the inertial force measured by this method.

A METHOD FOR DETERMINING THE IMPACT FORCE IN CRASH TESTING

A method for measuring the impact force in crash testing is developed. In this method, a mass is made to collide with the object being tested and the instantaneous value of the impact force is measured as the inertial force acting on the mass. To realise linear motion with sufficiently small friction acting on the mass, a pneumatic linear bearing is used, and the velocity and acceleration of the mass, the moving part of the bearing, are measured using an optical interferometer. The relative combined standard uncertainty in determining the impact force in a three-point bending test is estimated to be 0.5×10−2(0.5%) of the maximum value of the impact force.

Proposal for an impulse response evaluation method for force transducers

A method for evaluating the dynamic characteristics of force transducers in impact detection is proposed. In this method a mass is made to collide with a force transducer and the impulse, i.e. the time integration of the impact force, is measured highly accurately as a change in momentum of the mass. To realize linear motion with a sufficiently low friction acting on the mass, the pneumatic linear bearing `Air-Slide' is used, and the velocity of the mass, the moving part of the bearing, is measured using an optical interferometer. This method will be effective for evaluating the dynamic characteristics and the uncertainties of force transducers in impact detection, and evaluating the uncertainty in applying the results of other conventional dynamic calibration methods to impact detection. The relative combined standard uncertainty in the measurement of the impulse acting on a force transducer by this method is estimated to be less than .

Measurements of frictional characteristics of a pneumatic linear bearing

The forces acting on the moving part of a pneumatic linear bearing in the stationary state and during motion are difficult to measure directly because they are very small. Methods for measuring static and dynamic frictional characteristics of a pneumatic linear bearing in which the acceleration due to gravity is used as a uniform and steady acceleration field have been developed. The static force is estimated by measuring the range of the stage angle over which the moving part is at a standstill. The dynamic frictional force is estimated by using the difference between the accelerations of the moving part when it is travelling up and travelling down along a guideway tilted by a certain angle.