Consideration of dynamics is critical in the analysis, design, and control of robot systems. This article presents an extensive study of the dynamic properties of several important classes of robot...

Inertial properties in robotic manipulation: an object-level framework

In a preferred embodiment, linear stepper motor, comprising; an annular stator structure; an axially extending, cylindrical, permanent magnet shaft extending coaxially through said annular stator structure; and the axially extending, cylindrical, permanent magnet shaft having a smooth external surface along a portion thereof with axially alternating N and S poles defined circumferentially in an outer periphery of the portion of the axially extending, cylindrical, permanent magnet shaft. The present invention also provides a method of magnetizing the shaft of such a motor and a fixture and method of manufacturing the fixture therefor.

Linear stepper motor

The flexibility of the drives and structures of controlled motion systems are presented as an obstacle to be overcome in the design of high performance motion systems, particularly manipulator arms. The task and the measure of performance to be applied determine the technology appropriate to overcome this obstacle. Included in the technologies proposed are control algorithms (feedback and feed forward), passive damping enhancement, operational strategies, and structural design. Modeling of the distributed, nonlinear system is difficult, and alternative approaches are discussed. The author presents personal perspectives on the history, status, and future directions in this area.

Controlled Motion in an Elastic World

The present invention provides a system for performing a desired operation in a wellbore. The system contains a downhole tool which includes a mobility platform that is electrically operated to move the downhole tool in the wellbore and an end work device to perform the desired work. The downhole tool also includes an imaging device to provide pictures of the downhole environment. The data from the downhole tool is communicated to a surface computer, which controls the operation of the tool and displays pictures of the tool environment. Novel tactile sensors for use as imaging devices are also provided. In an alternative embodiment the downhole tool is composed of a base unit and a detachable work unit. The work unit includes the mobility platform, imaging device and the end work device. The tool is conveyed into the wellbore by a conveying member. The work unit detaches itself from the base unit, travels to the desired location in the wellbore and performs a predefined operation according to programmed instruction stored in the work unit. The work unit returns to the base unit, where it transfers data relating to the operation and can be recharged for further operation.

Downhole tools using artificial intelligence based control

A magnetic field sensor has two flux concentrators which serve to strengthen a magnetic field to be measured and which are separated by an air gap. Two Hall elements are arranged outside the air gap in such a way that at least a part of the field lines which lead from the first to the second flux concentrator pass through the two Hall elements in approximately opposite directions. Such a magnetic field sensor is less sensitive to external interference fields. It is suitable for the measurement of very weak magnetic fields and also for use as a current and/or energy sensor.

Magnetic field sensor and current and/or energy sensor

Magnetoresistive displacement transducer arrangement for toothed magnetic members in which each transducer is formed by a pair of interconnected sections spaced from each other by the width of a tooth to provide greater change and improved symmetry in the output signal at the tooth edges. Multiple transducers can be positioned interdigitally for compact packaging for vernier type detection of motion. Transducer embodiments for both linear and rotary motion are disclosed.

Interleaved magnetoresistive displacement transducers

The Hummingbird minipositioner is a three-axis servo-mechanism designed to provide fast and accurate positioning of a low-mass probe tip on or above a nearly planar object. Peak XYZ accelerations in excess of 500 m/s/sup 2/ (50 g) are obtained, with positioning resolution under 1 mu m and a workspace of 13 by 13 by 1 mm. The system weighs 950 g and is nearly reactionless during X-Y motion to simplify integration with large-area positioners. The design of the dynamically balanced five-bar linkage assembly and the Z-actuator is presented, along with data on in-plane linkage resonances (shown to be >1 kHz) and the torque cancellation effectiveness. A typical incremental move of 5 mm with 50 g peak acceleration and a move time of 8 ms is also presented. >

The Hummingbird minipositioner-providing three-axis motion at 50 g's with low reactions

A high performance, low cost variable reluctance stepper motor has an integral structure with a ring and a plurality of aligned salient pole members. A plurality of teeth are located on the face of each pole member. Windings are disposed on alternate ones of the pole members and a high impedance means isolates the pole members from one another. A rotor with a plurality of teeth and a plurality of holes disposed thereon coacts with the pole members and is moved in a step fashion by the sequential energization of the windings. The flux generated by the energization of the windings is confined to a short path and coupling to the remainder of the structure is negligible. Recesses positioned symmetrically around the structure also serve to enhance flux splitting and reduce adjacent flux coupling.

Low inertia high torque variable reluctance motor

The invention is concerned with circuitry for providing a sequence of stopping pulses derived from motor feedback pulses. It includes means for providing an initial stop pulse which reverses the phase of the motor to thereby develop a negative torque. Intermediate stopping pulses in the form of feedback pulses continue to apply the negative torque to the rotor. A final stopping pulse not derived from the feedback pulses is applied to bring the motor to its equilibrium position. In this manner, a stepping motor can be stopped with substantially no oscillations after a specified number of steps.

Logic circuitry for providing stopping control for stepping motors

A serial line printer uses a linear stepper motor of the variable reluctance type in which the toothed stator bar acts as a guide and support for the print mechanism carrier. Sensor elements movable with the carrier sense the presence of the teeth of the stator bar and generate timing signals usable for controlling operation of the printer and the motion of the carrier. The pitch of the teeth in the stator bar is proportional to the spacing of the print locations in a line of print.

Joseph P. Pawletko

Papers

Interleaved magnetoresistive displacement transducers

The Hummingbird minipositioner-providing three-axis motion at 50 g's with low reactions

Low inertia high torque variable reluctance motor

Logic circuitry for providing stopping control for stepping motors

Serial printer with linear motor drive