Showing papers on "Angular displacement published in 1990"
TL;DR: The study emphasizes the importance of head stabilization as part of the postural control system and described as a basis for inertial guidance.
Abstract: Head kinematics were studied in ten normal subjects while they executed various locomotor tasks The movement of the body was recorded with a video system which allowed a computer reconstruction of motion of joint articulations and other selected points on the body in three dimensions Analyses focus on head translation along the vertical axis and rotation in the sagittal plane This was done by recording the displacement of a line approximating the plane of horizontal semi-circular canals (the Frankfort plane: F-P) Four conditions were studied: free walking (W) walking in place (WIP) running in place (R) and hopping (H) In the 4 experimental conditions, amplitude and velocity of head translation along the vertical axis ranged from 1 cm to 25 cm and 015 m/s to 18 m/s In spite of the disparities in the tasks regarding the magnitude of dynamic components, we found a significant stabilization of the F-P around the earth horizontal Maximum amplitude of F-P rotation did not exceed 20° in the 4 situations Vertical angular velocities increased from locomotion tasks to the dynamic equilibrium task although the maximum values remained less than 140°/s Predominant frequencies of translations and rotations in all the tasks were within the range 04–35 Hz and harmonics were present up to 6–8 Hz During walking in darkness, mean head position is tilted downward, with the F-P always below the earth horizontal Darkness did not significantly influence the amplitude and velocity of head angular displacement during W, WIP and R, but during H the amplitude decreased by 37% Residual head angular displacement is found to compensate for head translation during the 4 conditions Our study emphasizes the importance of head stabilization as part of the postural control system and described as a basis for inertial guidance
850 citations
17 Jul 1990
TL;DR: In this article, the authors presented a new method for estimating angular position, velocity and load torque of permanent synchronous machines (PSMs) by combining the INFORM-principle ('indirect flux detection by online reactance measurement') by Schroedl and Stefan and the Kalman filter technique.
Abstract: Permanent synchronous machines (PSM) score against asynchronous machines because of their simple control structure and a higher efficiency due to the small rotor losses. The necessity of sensors for angular speed and position represents a considerable restriction of robustness. Because of this, it is the aim of much research to substitute the mechanical sensors with more sophisticated models using only electrical quantities. If a certain angular velocity is exceeded, it is possible to determine the electrical rotor position from the EMF, which can simply be calculated from electrical terminal quantities (Schroedl and Stefan (1988)). At standstill and at low angular velocity, the EMF decreases and thus cannot be utilized to detect the rotor position. The author presents a new method for estimating angular position, velocity and load torque of PSMs. The method works properly at any speed and load condition. It combines the INFORM-principle ('indirect flux detection by online reactance measurement') by Schroedl and Stefan and the Kalman filter technique. >
66 citations
Patent•
11 Jul 1990
TL;DR: In this article, an exoskeleton of T-shaped elements which resemble the spinous process and the transverse process of the spine is presented for monitoring the functional motion characteristics of the backbone in each of three planes.
Abstract: An apparatus is disclosed for monitoring the functional motion characteristics of the spine in each of three planes. The apparatus is designed to be mounted on the back of a patient and it includes an exoskeleton of T-shaped elements which resemble the spinous process and the transverse process of the spine. The elements each include a central bore for receiving a cable, and three separate openings for receiving a wire therethrough. The cable is attached to a potentiometer which measures twisting movement of the spine, and each of the three wires is attached to a separate potentiometer so as to measure flexing in the and sagittal and transverse planes. The signals from the potentiometers are processed so as to provide, for each of the three planes, a measurement of the angular position of the spine as a function of time, the angular velocity as a function of time, and the angular acceleration as a function of time.
66 citations
1 Oct 1990
TL;DR: This paper introduces a number of issues concerning the use of an inertial system in cooperation with vision, and presents applications of inertial information in a visual system, and attacks the problem of determining motion and orientation of the robotic system from inertial Information.
Abstract: This paper introduces a number of issues concerning the use of an inertial system in cooperation with vision. We first present applications of inertial information in a visual system, and then attack the problem of determining motion and orientation of the robotic system from inertial information. An iterative algorithm is finally given, and studied in detail.
54 citations
TL;DR: The mechanical stimulation of hair cells may be particularly simple at high frequencies where the structural differences in hair bundles and tectorial attachments--that have been shown to be important at low frequencies--play a less important role.
53 citations
TL;DR: In this article, two angular displacement sensors are spaced apart at a well-defined distance, and the rotor of each of these sensors is composed of an array of electrodes and sine-wave voltages with phase angles in the sequences 0 degrees, 90 degrees, 180 degrees, 270 degrees applied to it.
Abstract: The measurement of the torque in a mechanically loaded axle is often required for automotive power-train and engine-control systems. Torque sensing has been performed by mainly using strain gauges connected to the axle with slip rings to allow the electrical contacting. Noncontact magnetic and optical techniques have also been used. In the proposed capacitive torque sensor, two angular displacement sensors are spaced apart at a well-defined distance. The rotor of each of these capacitive displacement sensors is composed of an array of electrodes and sine-wave voltages with phase angles in the sequences 0 degrees , 90 degrees , 180 degrees , 270 degrees applied to it. These voltages are capacitively coupled from the stator to the rotor. The stator is also equipped with a readout electrode. The phase angle of the sine wave on this readout electrode is proportional to the rotor-to-stator electrode overlapping and thus proportional to the angular position. The phase difference between the output signals of the angular displacement transducers is a direct measure of the twist angle and thus of the torque in the axle. The sensor allows the noncontact torque measurement on a 10-mm-diameter steel axle in the 0-100-N-m range. >
41 citations
Patent•
30 Apr 1990
TL;DR: In this paper, a method and system for controlling radial movement of a machine tool, such as a turning machine, relative to a workpiece (11), is characterized by a digital filter (70, 72, 74) which produces a filtered final control signal which is a function of both radial position and velocity of a cutting tool (24) of the turning machine.
Abstract: A method and system (10) for controlling radial movement of a machine tool, such as a turning machine, relative to a workpiece (11), is characterized by a digital filter (70, 72, 74) which produces a filtered final control signal which is a function of both radial position and velocity of a cutting tool (24) of the turning machine. The method and system (10) utilizes a tool position feedback signal which is compared with an initial control signal to produce a signal which is then digitally filtered to, in turn, provide the resulting final control signal. The surface geometry of the workpiece (11), such as a piston, is determined by a data matrix of angular, axial and radial position coordinants of the tool. An angular position signal representative of the angular position of the workpiece (11) and an axial position signal representative of the axial position of the cutting tool (24) relative to the workpiece (11) are both generated. The angular and axial position signals are correlated with the data matrix to generate the initial control signal. The control loop of the system (10) is closed within the software portion of the system (10) for increased reliability. Also, there is no need for velocity loop feedback with a velocity transducer. Feed forward compensation is performed in the software portion of the system (10). The digital filter (70, 72 74) is preferably implemented with a digital algorithm on a digital signal processing microprocessor of an axis control board (38).
36 citations
Patent•
15 Oct 1990TL;DR: In this article, a seismic directional sensor for solid-borne sound has at least one geophone with pronounced directional characteristic, which is correlated with the direction of a seismic ray extending at right angles to the longitudinal axis of the geophone.
Abstract: A seismic directional sensor for solid-borne sound has at least one geophone with pronounced directional characteristic. The measuring electrical vibration signals, which are obtained at different circumferential angular positions of the radial longitudinal axis of the geophone and are to be compared with one another, are correlated with the direction of a seismic ray extending at right angles to the longitudinal axis of the geophone, which is ineffective in its neural circumferential angular position. The neutral circumferential angular position is determined by the ratio of the amplitude of the measuring signals which are determined on both sides adjacent to the neutral circumferential angular position in effective circumferential angular positions of the geophone. The vibration pattern of the measuring signals is antiphase in relation to the respective other side. The seismic directional sensor permits universal application with accurate measurement results along with relatively simple design and easy operation.
34 citations
Patent•
10 Apr 1990
TL;DR: In this article, a directional drill bit utilizing pressurized fluid as a means for eroding earth in a forward path of the bit and being used to drill at least a portion of an arcuate path, comprises an elongate hollow body (10) having two sections (20,30) joined one to the other by a flexible joint (40), a box end connection (24), a jet nozzle (50), an articulation device comprising a spring (60) and a stop (70).
Abstract: A directional drill bit utilizing pressurized fluid as a means for eroding earth in a forward path of the bit and being used to drill at least a portion of an arcuate path, comprises an elongate hollow body (10) having two sections (20,30) joined one to the other by a flexible joint (40), a box end connection (24), a jet nozzle (50), an articulation device comprising a spring (60) and a stop (70), the articulation device being responsive to changes in fluid pressure by permitting a forward portion of the bit bearing the nozzle structure to change angular postion with respect to an aft portion of the bit, by the forward portion moving from a first position relative to the aft portion to a second position relative to the aft portion. The spring (60) is positioned in a manner which defines an initial, pre-selected degree of axial alignment describing a first angle formed by the relative position of the longitudinal axis of the first section with the longitudinal axis of the second section when the elongate hollow body is in its "at rest" position, that is, when no fluid is flowing through the drill bit. The stop is positioned in a manner which defines a final, pre-selected degree of axial alignment describing a second angle formed by the relative position of the longitudinal axis of the first section with the longitudinal axis of the second section when the elongate hollow body is in its maximum degree of angular displacement relative to the initial, pre-selected degree of axial alignment.
34 citations
Patent•
17 Apr 1990
TL;DR: In this paper, a method and apparatus for body joint rotation and measurement to isolate the joint under test is characterized by imposing movement on one member of the joint in a series of discrete increments, whereupon strain is measured at rest over a predetermined range of motion.
Abstract: A method and apparatus for body joint rotation and measurement to isolate the joint under test is characterized by imposing movement on one member of the joint in a series of discrete increments, whereupon strain is measured at rest over a predetermined range of motion. Measurement of static force v. displacement at each of a plurality of steps in the angular range provides a quantitative test and evaluation of the elastic component of joint stiffness that resists the applied angular displacement. In this way, a static stress-strain loop is produced for each plane of movement. The static modulus of elasticity is derived by the slope of the stress-strain loop at the extremes of the range of motion.
31 citations
TL;DR: It is shown here that a nonlinear regulator approach solves the problem of controlling the motion of a one-link flexible robot arm, allowing asymptotic trajectory tracking with internal stability.
Abstract: The problem of controlling the motion of a one-link flexible robot arm is considered. A nonlinear dynamic model is derived assuming that the flexibility is represented by elastic springs along the link. Taking as output the end-effector angular position, the resulting zero-dynamics is unstable. Therefore, inversion-based controllers cannot be used for tracking of output trajectories. Instead, it is shown here that a nonlinear regulator approach solves the problem, allowing asymptotic trajectory tracking with internal stability. Simulation results show the good performance of the overall controller and in particular the benefits achieved by a nonlinear design of the regulator.
Patent•
7 Mar 1990
TL;DR: In this article, an electronic device for measuring relative angular positional displacement and angular range of motion for body segments and articulating joints of the human skeleton is disclosed, which has a hand-held interface unit which is placed against the body segment or joint to be tested.
Abstract: An electronic device for measuring relative angular positional displacement and angular range of motion for body segments and articulating joints of the human skeleton is disclosed. The device has a hand-held interface unit which is placed against the body segment or joint to be tested. Mounted within the housing of the interface unit is a shaft with a pendulum at one end and an optical encoder at the other. As the body segment rotates or the joint articulates, the pendulum swings in the direction of gravity, causing the shaft to rotate. The optical encoder generates an electrical signal representative of the amount of rotation of the shaft. The generated signal is fed to a microprocessor which processes the information and can produce on a display the change in angular position relative to initial angular position or the angular range of motion of the body segment or articulating joint.
Patent•
21 Aug 1990
TL;DR: In this paper, an inertial stabilizing system for image stabilizing of hand-held optical instruments is presented, where an ultralight oscillogro (1-6) serves as a reference element by which the angular position in inertial space is detected.
Abstract: The present invention comprises an inertial stabilizing system to be used preferably in connection with image stabilizing of hand-held optical instruments. An ultralight oscillogyro (1-6) serves as a reference element by which the angular position in inertial space is detected. An electromechanical control system causes a gimbaled part (19) of the optics to assume essentially the same angular position in space assumed by the rotation plane of the rotor of the oscillogyro. The oscillogyro is modified for a widened angular range and the damping of the gyro is utilized for obtaining directly the possibility of target tracking.
Patent•
15 Aug 1990TL;DR: In this paper, an auger is attached by means of an axial mount at the base of the support column for enabling rotational inclination of the auger from (i) a vertical orientation wherein the augers is nearly parallel with the vertical axis of the base support column, (ii) through intermediate angles of inclination, to (iii) a substantially horizontal orientation wherein augers are adjacent to the support floor.
Abstract: An apparatus for removing bulk materials from a laterally enclosed storage area wherein the apparatus may be substantially buried within the bulk material. The apparatus includes a support column mounted at a base into a support floor. An auger is attached by means of an axial mount at the base of the support column for enabling rotational inclination of the auger from (i) a vertical orientation wherein the auger is nearly parallel with the vertical axis of the support column, (ii) through intermediate angles of inclination, to (iii) a substantially horizontal orientation wherein the auger is adjacent to the support floor. The suspension cable is coupled between the support column and auger to enable selective adjustment of auger inclination. A rotational displacement drive is coupled to the support column to rotate the column about its vertical axis, along with the attached auger. A rotational drive motor is mounted at a distal end of the auger. Rotation of the auger, along with revolution of the support column provide for progressive removal of conical layers of surface material with each 360 degree revolution. Continued inclination to the horizontal level enables the total volume of the storage area to be out loaded.
Patent•
14 Nov 1990
TL;DR: In this article, a roll of material is placed on a spindle mounted for rotation in a housing, the material is drawn off the roll and thus turns the spindle, and a speed controller is provided to apply the necessary change in speed to the spindles rotation.
Abstract: A roll (12) of material (11) is placed on a spindle (14) mounted for rotation in a housing (22), the material is drawn off the roll and thus turns the spindle. (The spindle may be motor driven). The housing (22) is able to accommodate an angular displacement to provide an indication of the tension in the material. A speed controller (38) is provided to apply the necessary change in speed to the spindle rotation, the amount of change being controlled by the amount of angular displacement. Both mechanical and electrical control arrangements are disclosed, one of which applies a brake force on tension below the optimum and the other of which releases a brake force for tension higher than the optimum.
Patent•
9 Oct 1990
TL;DR: In this article, a photoelectric cell was used to detect the penetration of a person in a corresponding passage, in the authorized direction, in order to make the shaft (5) of the gate turn in the opening direction.
Abstract: The installation is comprised of a gate of which the leaf (3) is supported by a vertical shaft (5) rotationaly driven by motor (9) servo-controlled by a control system which includes a photoelectric cell capable of detecting the penetration of a person in a corresponding passage, in the authorized direction, in order to make the shaft (5) of the gate turn in the opening direction. The installation is also comprised of a central system for managing the operation of the gate and for actuating the motor (9) in one direction and in the opposite direction, and such managing system is servocontrolled by electromechanically control means (17) for both directions of rotation of the shaft (5) of the gate (2) as well as for the angular position of said shaft. In the case of rotation of the gate in an unauthorized direction, while the gate was previously closed or during its opening, this managing system is capable of controlling on the one hand the operation of a warning apparatus and on the other hand maintaining in operation or setting in operation a device (13, 14) for braking the shaft (5) of the gate, such braking device being capable of slowing down the shaft through out its rotation in the unauthorized direction while allowing such rotation under the effect of a pushing force exceeding a predetermined value.
Patent•
25 Oct 1990
TL;DR: In this paper, a roping training appartus is adapted to simulate on a fixed platform the relative movement between a rider and an object to be roped in certain roping maneuvers.
Abstract: A roping training appartus is adapted to simulate on a fixed platform the relative movement between a rider and an object to be roped in certain roping maneuvers, particularly heading and heeling in Dally team roping. The roping training device includes an elongated roping target and a mount simulator for supporting a trainee in a riding position within a desired training distance range from the target body. The target body is mounted on a target body pivot mechanism to allow the roping target body to pivot about a substantially vertical target rotational axis and the mount simulator is mounted on a mount pivot mechanism enabling the mount simulator to pivot about a substantially vertical mount rotational axis. The mount rotational axis and the target rotational axis are offset a desired initial heeling separation distance along an X coordinate axis and a desired initial heading separation distance along a Y coordinate axis, the X and Y axes being substantially perpendicular and defining a horizontal plane. A pivoting arrangement is connected to both the roping target and the mount simulator for pivoting the roping target body about its rotational axis and the mount simulator about its rotational axis, each a simulating angular displacement in the same rotational direction to simulate the relative movement between a rider and an object to be roped to simulate certain roping maneuvers.
Patent•
30 Mar 1990
TL;DR: In this article, a main body with a base and a screen-type dialogue means are placed in a flat casing connected to the main body by support means and means for maintaining the angular position.
Abstract: The device includes, on the one hand, a main body with a base (2) and, on the other hand, screen-type dialogue means (7) which are placed in a flat casing connected to the main body (2) by support means and means for maintaining the angular position (14) which can be regulated both for height and for angle. Said means for maintaining the angular position (14) are arranged coaxially to a pivoting axis XX' of a support arm (15) on the body (2) and include a free-wheel device mechanically located in series with a friction angular coupling device. The invention makes it considerably easier to adjust the position of the dialogue means.
13 Feb 1990
TL;DR: In this paper, a digital optical sensor is described which was developed to transmit the angular position of such slowly rotating parts as a throttle of fuel flow control valve on an aircraft, employing a reflective code plate with ten channels providing a resolution of 0.35 degrees.
Abstract: Future aircraft will use fly-by-light control systems with fiber-linked optical sensors for such measurands as temperature, pressure, and linear and angular position. A digital optical sensor is described which was developed to transmit the angular position of such slowly rotating parts as a throttle of fuel flow control valve on an aircraft. The sensor employs a reflective code plate with ten channels providing a resolution of 0.35 degrees. Two light-emitting diodes with overlapping spectra are used as light sources. A single microoptic multiplexer-demultiplexer composed of a GRIN rod lens and a miniature grating is used to disperse the spectrum and recombine the spectral components from each channel after reflection by the code plate. The results of preliminary environmental tests of this unit are discussed. The sensor has been operated for brief periods of time between -60 C and +125 without adverse effects. Preliminary vibration tests indicate that the unit will work properly at the maximum vibration levels expected in a jet-engine environment.
TL;DR: In this paper, the influence of the angular acceleration, the initial angular position of the unbalance ψn and the initial rotating speed ω on the maximum amplitude of a flexible rotating shaft with nonlinear spring characteristics during acceleration through a critical speed of a summed-and-differential harmonic oscillation was investigated.
Abstract: Nonstationary vibration of a flexible rotating shaft with nonlinear spring characteristics during acceleration through a critical speed of a summed-and-differential harmonic oscillation was investigated. In numerical simulations, we investigated the influence of the angular acceleration λ, the initial angular position of the unbalance ψn and the initial rotating speed ω on the maximum amplitude. We also performed experiments with various angular accelerations. The following results were obtained: (1) the maximum amplitude depends not only on λ but also on ψn and ω: (2) when the initial angular position ψn changes. the maximum amplitude varies between two values. The upper and lower bounds of the maximum amplitude do not change monotonously for the angular acceleration: (3) In order to always pass the critical speed with finite amplitude during acceleration. the value of λ must exceed a certain critical value.
Patent•
12 Nov 1990
TL;DR: In this paper, means of angular positioning are provided on the cylinder and the body in order to allow the rotation of the cylinder only over an angular range from which the assembly/separation position mentioned above is excluded.
Abstract: The tank cap comprises a body (2) provided with a housing (3) capable of receiving a cylinder (7) connected in translation with the body but able to rotate under the action of an appropriate key. Means (V) of locking the cap on the end of a tank pipe (12), controlled by the rotation of the cylinder (7), comprise only one part (13) mounted in a rotary manner on the body (2) and which can be put into position on this body by a movement of translation in respect of a relative angular position of assembly/separation of the part (13) with respect to the body (2). The said part (13) comprises retaining means (R,16) on the pipe (12). The connection in translation of the part (13) and of the body (2) is obtained by a rotation, after the putting in position of the part (13), separating it from the angular position of assembly/separation. Means of angular positioning are provided on the cylinder and the body in order to allow the rotation of the cylinder only over an angular range from which the assembly/separation position mentioned above is excluded.
Patent•
22 May 1990
TL;DR: In this paper, the angular position of two coaxial parts (27, 40) in relative rotation operating through variation of the magnetic reluctance was determined using a set of sensors, each consisting of a toothed rotor and a stator.
Abstract: Sensor for determining the angular position of two coaxial parts (27, 40) in relative rotation operating through variation of the magnetic reluctance. The sensors (25, 26) according to the invention, employed individually or as a group, thus forming an assembly for determining angular position, each comprise a toothed rotor (1) and a toothed stator (2), the latter possessing twice as many teeth as the rotor. There are means of mechanical linking (41, 42) between the rotors (1) on the one hand, and between the stators (2) on the other hand; the angular offset between the teeth (3 and 4) differs for each sensor, the difference generally being a multiple of the quotient of 2 pi by the number of teeth and the number of sensors, a two-phase coil or two single-phase coils are arranged on the rotor (1) or the stator (2) of each sensor and the alternating current passing through it depends on the relative position of the stator (2) and of the rotor (1). This device is designed more especially for robotics.
Patent•
23 Oct 1990TL;DR: In this paper, the angular position of the sensed object is corrected for precessional error based on estimates using the predetermined rate adjusted by the measured actual changes in the pre-cessional rate as determined by measuring accelerations about axes orthogonal to the spin axis.
Abstract: A method for navigating a spinning body to intercept an object includes configuring the body to have a predetermined nominal precessional rate and measuring actual changes in the precessional rate. The angular position of the sensed object is corrected for precessional error based on estimates using the predetermined rate adjusted by the measured actual changes in the precessional rate as determined by measuring accelerations about axes orthogonal to the spin axis. Changes in spin rate are determined via measuring acceleration about the spin axis and the sensed object angular position corrected for this error as well. Discrete thrusters are activated to propel the body in a direction to reduce differences between corrected object angular position and a predetermined position which may be the previously corrected sensed position. The projectile using the above method includes a cylinder body having a face-mounted sensor, a moment of inertia ratio of nominally 2:1 to yield an asymptotically imbalanced body, and two matched accelerometers pairs to determine changes in precessional rate. Changes in spin rate are determined by another matched accelerometer pair. The accelerometer pairs are mounted in a plane orthogonal to the spin axis and passing through the body CG.
Patent•
4 Oct 1990
TL;DR: In this paper, a tachogenerator with a rotor position transmitter for a three-phase servomotor having rotation-speed regulation and electronic commutation is presented, which is based on an annular stator core and a permanent magnet mounted on a rotating body.
Abstract: The invention relates to a tachogenerator with a rotor position transmitter for a three-phase servomotor having rotation-speed regulation and electronic commutation. The tachogenerator is formed by an annular stator core (2) and a permanent magnet (7) which is mounted therein on a rotating body (6). The rotor position transmitter consists of three Hall sensors (3), which are fitted at offset angles, and an impeller wheel (8) which is connected to the rotating body (6). According to the invention, a mounting body (1), which is fitted with the other components, has an annular flange (9) with elongated holes (12) so that the mounting body can be mounted at an optimised angular position with respect to a bearing plate of the three-phase servomotor. Furthermore, the stator core (2) can also be adjusted in the rotation direction via a detachable mounting into an optimum angular position with respect to the mounting body (1). In a further refinement of the invention, the impeller wheel (8) can also be mounted on the rotating body (6), in an optimum position with respect to said rotating body (6), via elongated hole connections. This results in it being possible to match all the parts of the tachogenerator and of the rotor position transmitter to one another irrespective of the geometry of the three-phase servomotor, for optimisation.
Patent•
26 Oct 1990TL;DR: In this paper, an optical rotary encoder having a rotatable pulse scale having a row of code pattern with specific light-permeable or deflection slits each adapted to reduce the amount of light for outputting an angular signal is presented.
Abstract: An optical rotary encoder having a rotatable pulse scale having a row of code pattern with specific light-permeable or-deflection slits each for outputting a reference position signal and other light-permeable or reflection slits each adapted to reduce the amount of light for outputting an angular signal, both of the optical signals being photoelectronically converted and the waveform of the resultant electric signals being shaped based on threshold voltages into electric pulse signals indicative of a reference angle of 0° and the accumulated angle of rotation, in which the circumferential width of each specific reference slit is made narrower than that of other slit so that the pulse width for angular position indicating of the angular pulse signal is always equal and constant for ensuring more accurate detection of the angle of rotation.
Patent•
23 Jul 1990TL;DR: In this paper, the displacement of a very detailed waveform on a multi-pixel detector from a known point on the detector is calculated by aligning the beamline to a fiducial angle.
Abstract: Optical apparatus for measuring angles to a precision approaching the theoretical optical limit for a fixed aperture. Calculations and measurement of the angle are made on the basis of the displacement of a very detailed waveform on a multi-pixel detector from a known point on the detector. The angle this displacement represents is created by the angular displacement of a dispersive element attached to the object of interest. The beamline comprises an optical source, the dispersive element on the object, and a spectrometer which contains an echelle and the detector. The known point on the detector is established by aligning the beamline to a fiducial angle.
Patent•
11 Jan 1990
TL;DR: In this paper, a dual implement hitch for pivotal connection to the drawbar of a towing vehicle whereby a pair of implements can be selectively towed in different relative positions without disconnecting the implements from the hitch and reconnecting same in different positions.
Abstract: A dual implement hitch for pivotal connection to the drawbar of a towing vehicle whereby a pair of implements, such as rakes, tedders and the like may be selectively towed in different relative positions without disconnecting the implements from the hitch and reconnecting same in different positions. The hitch comprises an arched longitudinal frame having a clevis at its front end for connection to a towing vehicle and a transverse frame, supported by wheels at its opposite ends, pivoted to the rear end of the longitudinal frame to swing about a vertical axes. A power actuator is connected between the arched longitudinal frame and the transverse frame for changing the angular position of the transverse frame relative to the longitudinal frame. A first drawbar, fixed to the front end of the hitch, extends rearwardly for towing as implement under the longitudinal frame, and a second drawbar, fixed to the transverse frame, rearwardly thereof for towing an implement to the rear of the hitch. Changing the angular position of the transverse frame member, relative to the longitudinal frame member causes the rear end of the hitch to shift to the right or left depending upon the direction of angular change produced by the power actuator.
3 Jul 1990
TL;DR: The authors propose an active touch approach using joint compliance to find a contact point between a multifingered hand and an unknown object using a suitable combination of compliant joints and position-controlled joints.
Abstract: Focuses on a scheme for searching a contact point between a multifingered hand and an unknown object. Instead of mounting a distributed tactile sensor all over the finger links, the authors propose an active touch approach using joint compliance. The algorithm is composed of two phases. One is the approach phase, in which each finger is opened widely and approaches to an object until a part of a finger link is in contact with the object. The other is the detection phase, in which each finger posture is changed with slip while maintaining contact between object and finger. Using two selected postures during the detection phase, one can compute the intersecting point which leads to an approximate contact point. With a suitable combination of compliant joints and position-controlled joints, a finger link has the capability of changing its posture while maintaining contact with an object over a small angular displacement at a particular joint. This motion is essential in the contact point detection phase. The proposed algorithm is confirmed through simple experiments using a two-fingered robot hand. >
1 Jan 1990
TL;DR: In this paper, a parametric identification technique is developed which is applicable to data acquired from a ship rolling in irregular unidirectional beam waves, and it is shown that both the linear and non-linear damping coefficients in the parametric model can be estimated with reasonable accuracy through and analysis of roll data acquired in the irregular wave situation.
Abstract: A parametric identification technique is developed which is applicable to data acquired from a ship rolling in irregular unidirectional beam waves. It is shown that, if an appropriate parametric model relating the wave elevation history to the roll angular displacement history is adopted, it is possible to estimate all the unknown parameters in the model by suitably processing simultaneous, digitised records of the wave elevation history and the roll angular displacement history. Application of the method to experimental data acquired from a scale model of a ship is shown to result in parameter estimates with good convergence characteristics and final values in satisfactory agreement with corresponding values deduced from calm water tests. In particular, it is demonstrated that both the linear and non-linear damping coefficients in the parametric model can be estimated with reasonable accuracy through and analysis of roll data acquired in the irregular wave situation.
TL;DR: Angular displacement sensors were installed on an instrumented lawn and garden tractor to sense vehicle pitch and roll angle as mentioned in this paper, where two small inclinometers were mounted at right angles to each other onto the tractor frame.
Abstract: Angular displacement sensors were installed on an instrumented lawn and garden tractor to sense vehicle pitch and roll angle. Two small inclinometers were mounted at right angles to each other onto the tractor frame. The sensors were located above the rear axle. Rather than mechanical movement, the sensor detected the distribution of a dielectric liquid and inert gas pressed between two etched copper-plated discs. Capacitance variations, caused by the gravity-induced repositioning of the mixture, indicated angular displacement. A simple circuit for computer interfacing of the sensor was developed. Roll and pitch angle performance data were collected at differing speeds over a surveyed calibration course. The inexpensive inclinometers were slightly influenced by vehicle acceleration and deceleration, yet acceptable results were obtained for a desired application.