Showing papers on "Angular displacement published in 1993"

Time-varying mechanical behavior of multijointed arm in man

Abstract: 1. The aim of this study was to describe the time-varying changes in the mechanical parameters of a multijointed limb. The parameters we considered are the coefficients of stiffness, viscosity, and inertia. Continuous pseudorandom perturbations were applied at the elbow joint during a catching task. A modified version of an ensemble technique was used for the identification of time-varying parameters. Torques at the elbow and wrist joints were then modeled with a linear combination of the changes in angular position and velocity weighted by the matrix of angular stiffness and the matrix of angular viscosity, respectively. Control experiments were also performed that involved the stationary maintenance of a given limb posture by resisting actively the applied perturbations. Different limb postures were examined in each such experiment to investigate the dependence of the mechanical parameters on limb geometry. 2. The technique for the identification of limb mechanical parameters proved adequate. The input perturbations applied at the elbow joint elicited angular oscillations at the wrist essentially uncorrelated with those produced at the elbow. The frequency of oscillation is much higher at the wrist than at the elbow, mainly because of the smaller inertia. The variance accounted for by the model was approximately 80% under both stationary and time-varying conditions; in the latter case the value did not vary significantly throughout the task. In addition, the model predicted values of the inertial parameters that were close to the anthropometric measures, and it reproduced the stepwise increase in limb inertia that occurs at the time the ball is held in the hand. 3. The values of angular stiffness and viscosity estimated under stationary conditions did not vary significantly with joint angle, in agreement with previous results obtained under quasi-static postural conditions. The matrix of the coefficients of angular stiffness was not symmetrical, indicating a prominent role for nonautogenic reflex feedbacks with unequal gains for elbow and wrist muscles. 4. A complex temporal modulation of angular stiffness and viscosity was observed during the catching task. The changes in the direct coefficients of angular stiffness tended to covary with those in the coupling coefficients from trial start up to approximately 30 ms before impact time. Around impact time, however, there was a complete dissociation: the direct terms peaked, whereas the coupling terms dropped. The direct terms of angular viscosity also increased before impact, whereas the viscosity coupling terms remained close to zero throughout.(ABSTRACT TRUNCATED AT 400 WORDS)

Head tracking apparatus

Abstract: A low cost head tracker for a virtual reality head set for determining the orientation of the head set relative to the earth's magnetic field includes a magnetic sensor responsive to the earth's magnetic field, and disposed on the head set and arranged with respect to a vertical axis of rotation of the head set to produce a displacement signal relative to the angular displacement of the head set with respect to a calibration orientation relative to the earth's magnetic field, and a signal processor connected to the magnetic sensor, and responsive to the electrical displacement signal for producing an output signal proportional to the orientation of the head set relative to the calibration orientation.

Electrical drive system for adjusting one or more rotatable and/or pivotable functional parts in devices and machines, drive arrangement with an angular position transmitter and printing machine

Abstract: Electric drive system for adjusting one or more rotatable and/or pivotable functional parts of devices and machines, in particular of printing machines, in their angular position, having at least one electric motor whose rotor is constructed for rigid and direct connection to the functional part, in which system, by means of one or more angular position transmitters, the angular movements of the electric motor rotor and/or functional part are picked up, a signal processing module which is connected on the input side for picking up the angular position signals as current values is connected to the angle transmitter or transmitters and is designed to pick up desired values and to compare them with the current values, and a power amplifier which is controlled by the signal processing module and which is connected on its output side to the electric motor for driving it.

Manually operated hand-held optical scanner with tactile speed control assembly

Abstract: A hand-held optical scanner comprising an optical sensor for generating a data signal representative of a scanned object; a housing for hand-displaceably supporting the optical sensor; a roller mounted on the housing for enabling rolling displacement of the housing over a scanned object in a predetermined scan direction; a displacement sensing device for sensing the angular displacement of the roller and generating a displacement signal representative thereof; a motor drivingly linked to the roller for applying a driving torque thereto; a controller for actuating the motor responsive to the displacement signal for angularly accelerating and decelerating the roller for urging an operator to hand displace the housing across a scanned object within a predetermined speed range which is optimal for scanning.

Optical angle sensor using polarization techniques

Abstract: A three-phase angular position sensor is described in which three beams of light having polarization directions rotated 60° to each other are passed through a polarizer, the rotational position of the polarizer representing an angle to be measured. The intensities of the beams transmitted through the polarizer uniquely encode its angle over a 180° range. This range may be doubled, for example, by including a binary track. A two-phase angular position sensor is also described in which two beams have polarization directions oriented 45° with respect to one another.

Capacitive angular displacement transducer

Abstract: Measuring device for the measurement of a rotor angle including a capacitive angular displacement transducer generating an output that varies with an angular displacement of a shaft. A first stator has a plurality of transmitting electrodes to generate electric fields within the transducer due to excitation signals applied to the plurality of transmitting electrodes which are electrically conducting circle sectors of equal area which are electrically isolated from each other and which completely cover a rotational angle of 2π on the first stator. A second stator is parallel and coaxial to the first stator and includes a conductive ring electrode receiving excitation from the first stator and producing an electric output signal. A rotor is located coaxially, parallel to the first stator and the second stator. The rotor has at least one rotor blade in the form of circle sectors, the central angle of each rotor blade being equal to at least the sum of the central angles of two sectors of the first stator. A generator delivers output voltages to the sectors. An evaluation unit is connected to the second stator and includes at least one separation unit connected via an amplifier to the second stator and a following signal processing unit. The generator provides at least two different electrically separable output signals. The separation unit separates the received input signal with respect to the excitation signals into angle dependent transfer functions. The following signal processing unit determines the rotor angle from the angle dependent transfer functions.

Local vertical sensor for externally-guided projectiles

Abstract: An improved local vertical reference determination technique for use with projectile guidance systems. The vertical reference determination apparatus uses a passive retroreflector mounted on the projectile to direct a portion of the incident electromagnetic radiation produced by a launching device transceiver as a return signal back to the launching device transceiver. A preferred embodiment of the invention employs a retroreflector having an axis canted with respect to the central axis of the projectile, such that the return signal is a function of the instantaneous angle of rotation of the projectile. The return signal therefore has a minimum magnitude at a first instantaneous angle of rotation and a maximum magnitude at a second instantaneous angle of rotation. The retroreflector is mounted on the projectile such that the return signal is at either the minimum magnitude or the maximum magnitude when the vertical axis of the projectile is aligned with the local vertical reference of the projectile guidance system. An alternate embodiment employs a retroreflector having a single facet. Another alternate embodiment uses a multifaceted retroreflector having at least two facets, where a first facet has a first coefficient of reflectivity and a second facet has a second coefficient of reflectivity substantially different from the first. The single-facet and multifaceted retroreflectors produce return signals having magnitudes strongly dependent upon the instantaneous angular position of the projectile.

Connection between components

Abstract: A connection assembly includes at least two components each formed with a body extending along a respective axis and a respective plurality of angularly equispaced alternating tongues projecting radially from the body and grooves for meshing with the tongues and grooves of the other component upon relative angular displacement of the components, so that the components are not able to be separated in a direction transverse to the axis upon the relative angular displacement.

Geometric methods in determining rigid-body dynamics

Abstract: This research develops a measurement system using linear accelerometers to determine the three-dimensional, six degrees of freedom, impact response of an anthropomorphic test device (dummy). A procedure using spherical geometric analysis (SGA) was developed. It uses three triaxial accelerometer clusters for determining angular velocity, angular acceleration, and linear acceleration. SGA differs in its calculation of angular velocity from other procedures which determine rigid-body motion. Unlike procedures which use linear accelerometers to determine angular velocity by integration of angular acceleration, SGA uses the topology of the sphere to obtain both angular acceleration and angular velocity through algebraic manipulation of the output from the linear accelerations. The validation of SGA is accomplished by the use of hypothetical as well as experimental data.

Vehicle-type motion estimation from multi-frame images

Abstract: A model for vehicle-type motion, which assumes that the motion is a rotation around an axis through the vehicle center followed by a forward translation along the main axis of the vehicle, is proposed. When the rotation and the amplitude of translation are constant, this type of motion is shown to be equivalent to a constant camera-centered motion. This indicates that a constant motion in the conventional camera-centered model, which is commonly considered to be artificial, can in fact be a reasonable model in real life. It is shown that a constant vehicle-type motion can be interpreted as a constant screw motion. A linear algorithm for estimating constant vehicle-type motion is presented, and experiments using real scene images are included. As an extension, vehicle-type motion with constant rotation and constantly accelerated translation is discussed. >

Method and apparatus for cancellation of rotational unbalance

Abstract: A device (19) for generating a rotating force vector and an oscillatory couple includes a plurality of non-concentric eccentric masses (22A, 22B, 22C, 22D, 22E, 22F) co-rotating at the same angular speed; and means (24A, 24B, 24C, 24D, 24E, 24F) for individually controlling the angular position of each of the masses; whereby, by selectively controlling the angular position of each eccentric mass, the device may generate a desired rotating force vector and a desired oscillatory couple. In use, the device performs an improved method for opposing the propagation of vibration from a dynamically unbalanced rotating rotor through a supporting structure (12). This method comprises the steps of: mounting a plurality of non-concentric rotatable eccentric masses on the supporting structure; co-rotating each eccentric mass at the same angular speed as the rotor, and controlling the angular position of each mass relative to the angular position of the rotor; thereby to generate a pattern of rotating inertial forces to oppose the transmission of vibration from the rotor through the supporting structure.

Method and device for earth acquisition using the pole star for a three-axis stabilized satellite in a low inclination orbit

Abstract: Earth acquisition from the Sun pointing attitude starts with angular displacement of the satellite so that, in the field of view of a Sun sensing system, the direction of the Sun is brought into an orientation S' such that subsequent rotation of the satellite about the orientation S' brings the Pole Star into the field of view of a star sensing system whose optical axis is substantially parallel to the pitch axis. During this rotation the stars sensed are compared with those in a catalog containing, in addition to the Pole Star, stars likely to be encountered upon such movement. At least two of these stars are identified and then the Pole Star is captured. The satellite is then rotated in pitch until the Earth is sensed and captured.

Apparatus for generating ophthalmic products from blanks and a method of operating same

Abstract: An apparatus for use in the generation of ophthalmic products from blanks comprises a mechanism for rotating the blank about an axis of rotation. A cutter tool imparts a desired surface configuration onto the rotating blank. A first moving mechanism moves the cutter tool in a first direction oriented parallel to the axis of rotation of the blank. A second moving mechanism moves the cutter tool in a second direction oriented transverse to the first axis. A digital electronic system controls the angular displacement of the blank with respect to a reference plane containing the blank, and controls the movements of the cutter tool in the first and second directions. The movements of the cutter tool in the first and second directions, and the angular displacement of the blank about the axis of rotation are all controlled independently of one another by the digital electronic system.

Three-dimensional joint range of motion measurements from skeletal coordinate data.

Abstract: Frequently, joint range of motion is reported for a single plane (eg., sagittal, coronal, or transverse). However, the arc of joint motion during functional activities and many clinical tests encompasses motion in all three planes simultaneously. The purposes of this paper are to discuss a method to obtain relative joint three-dimensional angular displacement measurements using coordinates from skeletal landmarks and provide an analytical example of the method using three-dimensional angular displacement of the knee joint as a model. In order to calculate the three-dimensional relative motion, an orthogonal reference frame for each bone needs to be established. To establish the local reference frame, three noncollinear points are used to define unit vectors that are mutually perpendicular. Three-dimensional angles can be determined to describe the magnitude of the moving body rotation angles about the X, Y, and Z axes. These angles indicate the relative motion of body segments for abduction/adduction, fle...

Method and means for correcting lateral registration errors

Abstract: A method and means for compensating for lateral registration errors in printing machines of the type having a plurality of image processing stations (A,B,C) for forming a composite image on an imageable surface (13) which moves relative to the stations. Monitoring means (146,156) are provided for determining the angular displacement ⌀ of the surface from a reference (302) in the process direction to thereby determine the lateral registration error at each of the image processing stations. Actuating means (138) are provided to move the image processing stations laterally relative to the surface to provide lateral registration of the images formed on the surface. Means may also be provided for compensating for process direction registration errors including means (139) to rotate the image processing stations relative to the surface to provide process direction registration of the images formed on the surface.

The Effects of Relative Angular Motions on Friction at Rough Planar Contacts

Abstract: Changes in friction due to angular motions at rough planar contacts are investigated using a compliant contact model that isolates an angular degree-of-freedom. Expressions are developed that relate the real area of contact, the contact forces and the line-of-action of the resultant normal contact force to the angular displacement for both periodic and random rough surfaces. We assume that the friction force is proportional to the real area of (elastic) contact. For a periodic rough surface, consisting of an array of hemispherical asperities of equal height and radius, the friction force is shown to be independent of angular displacement. The normal force increases and its line-of-action shifts away from the center of the contact as angular displacements increase. Therefore, the coefficient of friction decreases with angular displacement. In contrast, for a randomly rough surface, the contact area and normal contact force are shown to be non-linearly dependent on angular displacement, but remain proportional to each other in the presence of relative angular motion. Therefore, for the randomly rough surfaces the coefficient of friction is independent of angular motion.

Geomagnetic orientation sensor, means, and system

Abstract: The Geomagnetic Orientation Sensor is a device used to determine the orientation of objects with respect to the magnetic field surrounding the earth. The sensor may also be used to determine orientation with respect to a local magnetic field, a local attenuation of the earth's magnetic field, or used as a pointer to track moving magnetic potentials. The device incorporates three mutually orthogonal Hall effect generator pairs, the output voltage differentials of which are directly proportional to the magnetic field intensity and direction relative to each generator pair. A set of three differential amplifier circuits detect and amplify the small voltages induced by the geomagnetic field. The resulting voltages, V X , V Y , and V Z , are multiplied by a constant to acquire three orthogonal angular displacement values with a range of 0 degrees to 180 degrees. The device is further arranged with an analog to digital converter for subsequent analysis of the three indicative voltages by a digital computer, and a computer program that performs the necessary calculations to convert the 180 degree maximum angular displacement values to pitch, roll, and yaw numbers with a maximum value of 360 degrees. A second computer program performs the various calculations necessary to describe and display the orientation of remote objects on a computer display. The preceding embodiment may be referred to as a computer input device.

Method of moving a rotary fixture

Abstract: An improved method of moving a rotary fixture (20) from a first angular position to a second angular position includes the steps of: providing a body (25); mounting the fixture on the body for rotational movement about an axis (x--x); mounting a pin (23) in the spindle (22) of a machine tool; moving the pin so as to engage the fixture at a location eccentric to the axis; and selectively moving the pin relative to the axis from one location to another; thereby to rotate the fixture from the first angular position to the second angular position.

Programmable system for the synchronization of an electronic angular position indicator

Abstract: A programmable system synchronizes the operation of an electronic angular position indicator with the angular displacement of a rotor. The system can synchronize operation with rotors with non-uniform mark spacing. A sensor provides the system with electronic pulse patterns corresponding to marks on the rotor. Pulse patterns are compared to patterns stored in memory to determine the instantaneous angular position of the rotor. The synchronization system provides the angular position indicator with parameters appropriate to the angular position of the rotor. The system obtains synchronization during initial rotations of the rotor and continually checks synchronization during subsequent rotation.

Image-blur preventing apparatus

Abstract: An image-blur preventing apparatus includes an image-blur correcting device that is driven in accordance with a subject distance to compensate for the location of an image-blur correcting optical device being located at a position different from a rotational center of the apparatus corresponding to rotational displacement due to a hand shake. The rotational center can be specified at a constant point, and a simple relationship between the needed correction and the subject distance can be established, thereby enabling image-blur prevention.

Zero locus of a beam with varying sensor and actuator locations

Abstract: The nonrational transfer function of an important component of a flexible structure, the beam, is analyzed. The true pattern of zeros of that transfer function is investigated as a function of sensor and actuator separation. Translational displacement sensors are used for two cases in which a force input and a moment input are separately applied at one end of the beam. Contrary to general opinion, zeros do not simply approach the origin along the real axis of the s plane as the sensor is moved away from the point of force/moment application. When the displacement sensor is located at a certain point, the first pair of zeros on the real axis of the s plane arrive at the origin and cancel the rigid-body mode. The location of the translational displacement sensor on the beam at which the rigid-body mode of the beam is unobservable is analyzed as the center of percussion and is uniquely located for each case. If the sensor is moved beyond such a point, a pair of zeros appear on the imaginary axis and move away from the origin along the imaginary axis of the s plane. Finally, the zero migration associated with an angular displacement sensor is briefly considered and compared with the zero migration associated with the translational displacement sensor.

Start up circuit for continuous sine-wave commutated brushless motors

Abstract: Automatic start up of a continuous sine-wave commutated, brushless, direct current motor in a predetermined direction is done by applying a ramped armature current to the direct current motor to generate an armature field. The resulting armature field is rotated independent of angular position of the shaft. Upon rotation of the motor shaft beginning, the direction of rotation of the shaft is determined. Responsive to rotation of the shaft in an undesired direction, the direction of rotation of the armature field is reversed. A base angle of rotation of a shaft in the direct current motor is determined from an index mark as it rotates by an index mark detector. Responsive to detection of the index mark, rotation of the armature field and the angular position of the shaft are synchronized.

Cam shaft timing adjustment device

Abstract: Apparatus for permitting selective adjustment of the angular position of a sprocket or gear relative to a driven shaft for changing the timing of an internal combustion engine includes a circular sprocket carried on an end face of the cam shaft in axial alignment with the shaft's axis of rotation. A first pin extends from the end face parallel to the axis of rotation at a location radially outwardly thereof through an enlarged opening in the sprocket. An adjusting plate is engaged with the sprocket on the side opposite the end face. The adjusting plate is positively engaged with the first pin with a second pin extending between the adjusting plate and the sprocket parallel to the axis of rotation but at a radial location different than the first pin such that angular adjustment of the adjusting plate about the axis of the first pin produces angular adjustment of the sprocket relative to the axis of rotation of the shaft.

Optimising phase accuracy of belt drive - incrementally measuring driven and drive shaft positions, and compensating for angular deviation of driven shaft position

Abstract: The actual position of a driven shaft and of a drive shaft are each separately and incrementally measured. An angular deviation of the driven shaft is derived from its actual angular position and each computed desired angular position. A tensioning device in the slack belt section is adjusted so as to reduce the angular deviation. The actual angular position of the driven shaft is measured in relation to a reference position for that shaft. USE/ADVANTAGE - For optimizing phase accuracy between driven and driving shafts of belt drive. Enables angular deviations to be determined and compensated for.

Rotor Displacement of the Ultrasonic Motor Having an Angular Displacement Self-Correction Function

Abstract: This paper deals with the experimental investigation for confirmation of rotor displacement of the ultrasonic stepping motor having an angular displacement self-correction function. The experiment focused on the relationship between the rotor's vibration displacement and its staying position for the self-correction. The result proved that the rotor always stays at the position where the displacement is smallest by cutting a slit into the rotor. Moreover, it has also been found that the stable self-correction of rotor angular displacement depends upon both the rotor driving frequency and rotor clamping force.

Method for controlling the switching-off process (turning-off process, disconnection process) in the strands of a reluctance motor

Abstract: In the case of a method for controlling the turning-off process in the strands of a reluctance motor whose stator is provided with windings to which current pulses are fed in an impressed manner, said current pulses being calculated in accordance with a predetermined algorithm, as a function of the angular position and rotation speed of the rotor, the strand through which current is passing is turned off at a turning-off angle (vp) after the reference angle for the zero crossing (v0). In this case, it is necessary to distinguish between two operating regions which are called the "chop" region and block-voltage region. The invention provides that the turning-off angle (vp) is calculated using the same algorithm, and is set by a controller, for both operating ranges of the reluctance motor. In this case, a pulse-width-modulated voltage is applied to the live strand in the low rotation speed range, the "chop" range, and a constant voltage is applied in the upper range, the block-voltage range. The turning-off angle is calculated from the motor parameters and the actual operating variable in both ranges, subject to the condition that the torque yield is maximised and that the turning-off process is produced by the conversion of these variables into a turning-off pulse which turns off the live strand.

Bi-directional spatial optical communication device

Abstract: PURPOSE:To provide a device to correct angular displacement of a beam of light caused by environmental change unpredictable such as vibration, voltage, etc. CONSTITUTION:Dislocation information of a received beam spot on the photo- receiving surface of a photo-receiving element (for example, quadri partitite sensor) 8 provided for position sensing is sent to a mirror drive controlling part 12 as an optical axis shift correct signal via a signal processing part 11, to actuate a motor in the drive part of a mirror angle varying mechanism part 10, which rotates a total reflection mirror round two axes perpendicularly intersecting on the mirror face, and thereby the cycle of moving the beam spot is repeated so that the center of the beam spot is positioned in the neighborhood of the center of the photo-receiving surface of the photo-receiving element for position sensing. This is combined with rotation round the axis identical to the optical axis 13 on the beam splitter side so as to move the beam a spot with higher effectiveness, and thereby a control with better responsiveness is achieved.

Drive unit for a rotary decoration

Abstract: A drive unit for a rotary decoration has a transmission gear train configured to include a damper such as a coil spring and is capable of imparting a visually elegant swing motion to the rotary decoration. A reciprocating stepping motor is capable of rotating or turning in both the forward and reverse directions to drive a rotary decoration in such a manner that the rotary decoration exhibits a reciprocative swing motion over a specified angular displacement. A memory circuit stores data for determining the drive timing of the stepping motor. A control circuit controls the stepping motor in accordance with the data stored in the memory circuit. The data represents the interval between drive pulses supplied to the stepping motor so as to cause the rotational speed of the rotary decoration to vary according to a sine curve. In alternative embodiments, (1) the intervals between drive pulses are set to a uniform and short value in a predetermined region of the specified angular displacement; (2) the intervals between drive pulses are set to a short value in a predetermined region of the specified angular displacement which corresponds to the location immediately after which the rotational direction of the rotary decoration is reversed; and (3) the drive pulses are blanked over a predetermined region corresponding to the location immediately before the rotational direction of the rotary decoration is reversed.

Position sensor and application to measuring the angle of the throttle of a carburettor

Abstract: The invention relates to an angular position sensor (400) including a first magnetic armature (410) carrying at least two windings, namely a primary winding (430) and at least one secondary winding (440), and a second magnetic armature (420), placed in front of the first (410) and capable of moving in rotation about a measurement axis (M) with respect thereto, the two armatures (410) and (420) including two pairs of first and second concentric surfaces (414a, 422, 424, 416) arranged opposite to form two air gaps (418, 415), the said surfaces being centred on the measurement axis (M), wherein each of the pairs of opposite concentric surfaces includes a first surface (414a, 424) extending over an angular sector at least equal to the angular extent of the second surface (422, 416) opposite, plus an angle corresponding to the desired measurement range, with a view to having air gaps (418, 415) of constant reluctance for any relative angular displacement of the armatures (410, 420) in the measurement range.

A wavelength encoded rotary displacement sensor

Abstract: A novel concept for a digital rotary displacement sensor is presented. Broadband light issuing from the encoder input fibre is focused on a 9 bit Gray coded dis. Rays emerging from the disc under Littrow conditions are diffracted back to the input fibre by a grating. The output spectrum is encoded as a function of the disc's angular position. The theoretical prediction of the sensor's performance is developed and compared with experimental results. A prototype with a resolution of 0.7 degrees and a nonoperating range of 360 degrees has been successfully tested.