127 results about "Strain wave gearing" patented technology

Provided is a strain wave gearing having a high stiffness and no limitation imposed on rotation, and a robotic arm including the strain wave gearing. A strain wave gearing includes an electric motor and a strain wave gearing reducer. The strain wave gearing reducer includes: an outer ring member including a first internal gear; a pair of second internal gears each having internal teeth formed along an inner periphery thereof, and the pair of second internal gears differing from the first internal gear in number of teeth; a flexible gear; and a cam member, which distorts the flexible gear in a radial direction to cause the flexible gear to engage with the first internal gear and the pair of second internal gears. The pair of second internal gears is fixed to a pair of fixing plates coupled to each other by a shaft penetrating the cam member.

A rigid internal gear 2 of the wave gear device is composed by integrating a tooth-forming ring 12 formed with internal teeth, and a main gear ring 11 into a single body. The tooth-forming ring 12 is manufactured from a ferrous or copper material that has superior strength and abrasion resistance, while the main gear ring 11 is manufactured from a lightweight material, such as an aluminum alloy. The outer circumferential surface of the tooth-forming ring 12 is aluminized to form a dispersed aluminum coating 15, before the tooth-forming ring 12 is cast within the main gear ring 11 so as to integrate the main gear ring 11 and the tooth-forming ring 12. Both parts are reliably integrated so that a large amount of torque can be transmitted, whereby realizing a rigid internal gear that is lighter than conventional models.

A wave gear device has a rigid internal gear, a flexible external gear, and a wave generator. The tooth profiles of both gears are initially defined by a basic rack tooth profile shape. The lower parts of the dedendum portions of these tooth profiles are modified by curves C2 and C3 having pressure angles α2 and α3 that are less than the standard pressure angle α1 of the basic rack tooth profile shape C1. An increase in thickness of the tooth bottom side can be minimized even if the tooth depth is increased and the tooth thickness/tooth space ratio changed to increase the tooth thickness. Hence, the ratcheting torque of a wave gear device having a high reduction gear ratio can be increased without reducing the service life and strength of a pinion cutter for the rigid internal gear, or the fatigue strength of the flexible external gear.

A positioning system (1) provided with an actuator (2) having a wave gear device (4) is driven and controlled by a semi-closed loop control for controlling the load position of a load device (5) based on the motor position of a motor shaft (31) of a motor (3). In a method for compensating for an angular transmission error by compensating for a motor shaft synchronous component θSync that occurs in synchrony with the motor position and is a relative rotation-synchronous component that includes an angular transmission error component of the wave gear device (4), the positioning system (1) is represented as a two-inertia model, and the motor shaft synchronous component θSync is represented as an oscillation source for producing a twisting action between the two inertia bodies in the two-inertia model. A motor current command iref is corrected by a compensation current command icomp calculated so as to allow the effect of the motor shaft synchronous component θSync on the load position to be compensated in this case, and a motor position command r is corrected by a motor position correction signal θcomp calculated in order to compensate for the effect of the motor shaft synchronous component θSync.

A bending state known as “coning,” in which the amount of bending of the flexspline gradually decreases in accordance with the distance from the open end of the spline, occurs in cup-type or “silk hat”-type wave gear devices. A tooth profile in which the tooth depth is kept constant and in which the bottom lands and top lands are parallel to each other along the tooth trace direction is used as the basic tooth profile for the circular spline and the flexspline of the wave gear device. A taper surface is formed on a part of the top land near the open end of the flexspline in the basic tooth profile, whereby a modified tooth profile is obtained. The modified tooth profile is employed as the tooth profile for both of the splines. Both of the splines can be caused to mesh together without generating coning-induced interference. Both of the splines can also be subjected to gear cutting by a simple process using a typical machining mechanism.

A harmonic motor with a circular and internally geared stator, a flex spline coaxially arranged within the stator which comprises both external and internal gears, and a geared output shaft coaxially arranged within the flex spline. A drive assembly that includes a motor with a motor housing, a rotor, a rotor shaft, and a rear bearing for supporting the rotor shaft in the motor housing at a rear side of the rotor; and a strain wave gearing including a circular spline secured to the motor housing, a flex spline engaging the circular spline, a wave generator engaging the flex spline and secured to a drive end of the rotor shaft, and a wave generator bearing between the circular spline and the wave generator. The wave generator bearing serves as an exclusive drive end bearing for supporting the rotor shaft in the motor housing at a front side of the rotor.

The present invention relates to a joint assembly (1) for a robot (100), comprising a housing (26) connected with an output part (8), the housing comprising a housing wall (26A), a strain wave gearing system (90) comprising a wave generator (7), a flexspline (13), and a circular spline (36) connected to the output part (8), wherein the wave generator (7) is rotated by a rotor shaft (3), the rotor shaft being driven by an electric motor (140) comprising a stator (15) and a rotor magnet (16), the rotor magnet (16) being affixed to the rotor shaft (3), and wherein the joint assembly (1) further comprises a rotor brake (30) configured to stop/prevent relative movement between the rotor shaft (3) and the flexspline (13), and sensors arranged to measure the position of the housing (26) in relation to the output part (8). Furthermore, the present invention also relates to a robotic arm (100) comprising a joint assembly according to the present invention and to the use of the joint assembly according to the present invention.

Disclosed is a wave gear device (1) for setting the flexible state of the principal section (30) of a flexible external gear in a normal-deflection state (at a deflection coefficient κ=1). The moving locus of a tooth profile in the principal section (30) is determined by a rack approximation, and a similar curve (BC), which is obtained by similarly transforming a curve (AB) cut from that moving locus, is used to define the fundamental addendum shape of the tooth profile in the principal section. The portion of the tooth profile of the flexible external gear other than the principal section is shifted so that both each negative-deflection side moving locus (M3), which is obtained in each plane of rotation to deflect in a negative deflection state (at the deflection coefficient κ<1) closer to the diaphragm side than the principal section and each positive-deflection side moving locus (M2), which is obtained in each plane of rotation to deflect in a positive deflection state (at the deflection coefficient κ>1) closer to the front end opening side than the principal section, may become curves (M3a and M2a) to contact at the bottom (a point (P)) of a normal-deflection moving locus (M1). The partial meshing engagement can also be held at the section other than the principal section in the tooth trace direction, so that the load torque performance of the wave gear device can be advantageously improved.

A diaphragm of a cup-shaped flexible external gear of a cup-shaped wave gear device having a high reduction ratio of 100 or higher is given a thickness t in a position of a radius r of the diaphragm whereby the thickness t is a value that satisfies the expression A/r² when A is a constant. The constant A is preferably a value that satisfies the expression 0.0014D³<A<0.0026D³, where D is a pitch diameter of the flexible external gear, and the range of the radius r whereby the thickness t is defined as described above in the diaphragm is preferably set to satisfy the expression 0.6d<r<0.4D, where d is a diameter of a discoid rigid boss made continuous with an internal peripheral end of the diaphragm. Stress concentration can be alleviated, and it is possible for the allowable transmission torque to be increased compared to the prior art.

A flat type wave gear device is realized having a much improved load capacity. When d is an amount of radial flexing at a major axis location of a rim neutral circle of the flexible external gear of a flat type wave gear device flexed into an elliptical shape and t is the rim thickness of the flexible external gear, then

(0.5237 Ln(R)−1.32)d≦t≦(0.8728 Ln(R)−2.2)d

when the reduction ratio R of the wave gear device is less than 80, and

(1.5499 Ln(R)−5.8099)d≦t≦(2.5832 Ln(R)−9.6832)d

when the reduction ratio R of the wave gear device is 80 or more. Using this setting makes it possible to increase the tooth root fatigue limit strength of the flexible external gear, thereby making it possible to improve the load capacity of the flexible external gear.

A wave gear device torque detection method in which the gain of the output of each of a plurality of strain gauge sets affixed to the diaphragm of a flexible external gear is amplified and the outputs are then combined to form a detection signal. Adjusting the gain of each of the strain gauge outputs makes it possible to compensate for rotational ripple included in the output. Compensation of up to n order ripple components is possible by using at least (2n+1) strain gauges.

Provided is a wave gear device capable of transmitting a high torque. The silk hat type wave gear device comprises an annular circular spline having internal teeth formed thereon; a flexible flex spline having external teeth formed to mesh partially with the internal teeth and arranged on the inner side of the circular spline; and a wave generator arranged on the inner side of the flex spline. The flex spline includes a boss portion adapted to be fixed on an external member, and a connecting portion for connecting the external tooth portion and the boss portion. The connecting portion is so shaped that a sectional shape when cut in a plane extending through an axis of rotation of the flex spline is gradually reduced in thickness toward the substantial center from the side of the external tooth portion and the side of the boss portion.

The invention provides a compact and highly reliable motor vehicle steering device that does not require a spiral flat cable. The motor vehicle steering device includes variable gear ratio system that modifies the transmission ratio of the rotary motions between first steering shaft and second steering shaft. Variable gear ratio system comprises Strain Wave Gearing Speed Reducer that modifies the transmission ratio between first steering shaft and second steering shaft in response to the rotating speed of motor shaft. Motor shaft and second steering shaft forms a substantially concentric dual structure, drive motor is affixed, and output shaft is connected to motor shaft.

A positioning control system for an actuator provided with a strain wave gearing is provided with: a semi-closed feedback controller FB(s) that controls a load shaft position θ_l on the basis of a feedback motor shaft position θ_m; and a feedforward linearization compensator configured by incorporating a nonlinear plant model for an object to be controlled into a feedback linearization compensator using an exact linearization technique. The feedforward linearization compensator uses a forward-calculated state quantity estimated value x* to calculate a feedforward current instruction i*_ref and a feedforward motor position instruction θ*_m to be input into the feedback controller FB(s). A positioning error caused by a non-linear element (non-linear spring property, relative rotational synchronization component, and non-linear friction) of the strain wave gearing is compensated for by the feedforward linearization compensator.

In a wave gear device, the inner race and the boss are fixed together by a laser welded part formed along the entire periphery thereof. The laser welded part also functions as an oil seal for sealing the inner race and the boss. The boss and the inner race are fixed together in a manner that a required axial length is short, and that machining and assembling steps are reduced. Oil seal members are not required to seal the boss and the inner race.

In a positioning apparatus for an actuator, a sliding mode controller for compensating for nonlinear characteristics of a wave gear device of the actuator generates a control input u to a controlled object, based on a position command θ₁* and a state variable x for expressing the controlled object. The controlled object is defined in the following formula.

{dot over (x)}=Ax+Bu+Eθ_l*

The switching surfaces of the sliding mode control system are defined by a variable S expressed in the following formula.

The control input u is the sum of the linear-state feedback control term u_l and the nonlinear control input u_nl

where σ is the switching function, and k is the switching gain.

A strain wave gearing unit is provided with an internal gear, which surrounds the periphery of a cup-shaped external gear, and a bearing. An annular gap is formed between the inner ring of the bearing and the internal gear. The gap communicates with the sliding portions of the bearing and the section where the two gears mesh. An annular filter member made of non-woven fabric is fitted in the gap. Foreign matter such as abrasion powder, which is contained in lubricant that flows in the gap, is trapped by the filter member. The present invention can prevent penetration of abrasion powder generated in the sliding portions into the meshing section via the gap.

A wave gear device has a rigid internal gear, a flexible external gear, a wave generator, and a cross roller bearing for supporting the gears in a relatively rotatable manner. A toroidal composite member that functions as the rigid internal gear and an inner ring of the cross roller bearing has an inner ring-forming member that functions as the inner ring, and an internal teeth-forming member that functions as the rigid internal gear, and the internal teeth-forming member composed of a ductile casting is integrated by diffusion bonding with the inner ring-forming member composed of bearing steel.