GB1585658A - Robotic arm - Google Patents

Description

(54) ROBOTIC ARM (71) We, THE UNIVERSITY OF SURREY, a British Body Corporate of Guildford, Surrey, GU2 5XH, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to robotic arms for use in, for example, mechanical manipulators.

The arm which is particularly described by way of example is intended for use in a manipulator which is constituted by the arm and a control constituted, for example, by a microprocessor which controls the movements of the various parts of the arm so as to move the arm from a starting position to a final position which may be selected or pre-programmed.

Moreover, the arm is intended to provide positional adjustment of a hand, which may be in the form of a simple probe or container or might be some more complex device which might grip or otherwise manipulate an article.

However, the particular form of any hand that might be used with the arm, and the manner in which the arm might be controlled, by a microprocessor or otherwise, are not intended to constitute part of the invention or to limit the scope of the monopoly claimed.

This invention provides a robotic arm comprising a shoulder which is mounted for rotation, a first parallelogram linkage constituted by two parallel links connecting the shoulder to an elbow, a second parallelogram linkage constituted by two parallel links connecting the elbow to a wrist, and a respective rotary fluid motor, mounted on the shoulder and elbow respectively, disposed to provide rotation of the first parallel linkage and the second parallel linkage in the same place and with respect to the shoulder and the elbow respectively.

There follows a description of one embodiment of the invention by way of example and with reference to the accompanying drawings, in which: Figures 1 and 2 are sectional views, in side elevation and rear elevation respectively of a robotic arm; and Figure 3 is a sectional view, on the line A-A of the outer section of the arm illustrated in Figures 1 and 2.

The principal parts of the arms which is illustrated in the drawings are a shoulder, constituted by plates 8 and 8a, mounted for rotation in azimuth about a vertical shaft 46, an inner section, constituted by two parallel members 17 and 18, an elbow, constituted by bell-crank plates 25 and 25a, an outer section, constituted by parallel members 30 and 37, and a wrist, constituted by a bracket 36. The arm has three movements, namely the aximuthal rotation of the shoulder, and the rotations of the inner and outer sections relative to the shoulder and the elbow respectively. The inner and outer sections are both consituted by parallelogram linkages, in order that the wrist may, if desired, be maintained in a predetermined orientation notwithstanding rotation and elevation of the arm.Normally, angular elevation or depression of the inner section relative to the shoulder provides the principle movement of the hand towards its desired position, but the manner in which the degrees of freedom provided by the articulation of the arm are used is a matter of choice. The inner section is rotated in elevation about the shoulder by means of a rotary fluid motor which provides a controllable angularly adjustable joint between the shoulder and a pivot point of one of the members constituting the inner section, The outer section is similarly controlled relative to the elbow.

The arm has a baseplate 1 on which is disposed, horizontally, a bracket 2 to which is attached the outer end of a piston rod of a pneumatic cylinder 3. The cylinder has two end plates 53 which are secured one to each end of a rack 7 which is movable horizontally and lengthwise by means of the cylinder. The rack drives a pinion 48 which will be described in more detail. The rear face of the rack bears against a bearing 5 which is carried in a mounting block 4.

On the baseplate 1, in front of the cylinder 3 is a vertical shaft 46 which at its lower end is provided with a flange 51 secured to the baseplate 1. The shaft carries, immediately above the flange 51, a ring spacer 50 supporting the lower end of a cylinder spacer 49. At the upper end of the spacer 49 are two vertically spaced bearings 43 and 43a, spaced by a cylindrical spacer 44. The two bearings engage the inner end margins of a cylindrical case 45. At its lower end, the case 45 carries an annular end plate 47 which carries the pinion 48. The case 45 also carries two pairs of laterally extending studs which carry the side plates 8 and 8a.

The inner section of the arm is constituted by two channel section struts 17 and 18. The strut 17 is pivoted to the shoulder at its lower end by means of a shaft 21 which has lock nuts 20 at each end, a bearing liner 22 and, around the dry bearing a spacer bush 40. The lower side ends of the strut 18 are secured by means of brackets 16 to drive clamp plates 15, 15a which are keyed to the shaft of a "kinetrol" rotary fluid actuator of which the casing is secured to the plates 8 and 8a. The shaft of the actuator carries a gear of 80 teeth in mesh with a gear of 20 teeth, which latter gear is mounted on a shaft extending between the plates 8 and 8a and drives a further, similar gear 10a which forms part of a shaft encoder 12 for providing an indication of the angular position of the strut 18 relative to the shoulder.

Each of the channel section struts 17 and 18 is pivotally connected to the elbow, constituted by the plates 25 and 25a in the manner described for the lower end of the strut 17.

Inside the inner section is a pair of springs 59, which are anchored at their uppper ends to a bracket 19 between the plates 25 and 25a.

These springs provide tension between the elbow and the shoulder to counterbalance the arm. The springs are, at their lower ends, secured to a connector 61, by means of screws 60. The connector is connected by means of a turn buckle 62 to a T-bracket 41 carried on a short vertical strut extending upwardly from an end plate covering the upper end of the casing 45. A tensile spring may be connected between the elbow and the wrist to counterbalance the outer section.

The outer section comprises two struts 30 and 37. The strut 30, which is of channel section, is pivotally secured to the apex of the elbow by means of a shaft 29, which carries a liner 32, a spacer bush encircling the liner, and lock nuts 27 at each end of the shaft 29.

Each side panel of the strut 37 is secured to a respective drive arm, 39 and 39a, by means of a respective connecting bracket 78; the drive arms are connected to a "kinetrol" rotary actuator in a manner similar to the way in which the drive plates 15 and 15a are connected to the plates 8 and 8a.

The wrist is principally constituted by a bracket 36 which carries shafts 33 each of which bears a spacer 34 for maintaining the side arms of the bracket separate. The shafts 33 act as pivots for the bracket about the outer ends of the struts 30 and 37.

Appropriate pneumatic lines, not shown, provide pressure for the actuators, of which each is capable of continuous movement throughout its range of movement; it is preferable that each motor be not inherently adapted for incremental movement but that positioning be achieved by means of only external control valves and the micro-processor that governs them.

WHAT WE CLAIM IS: 1. A robotic arm comprising a shoulder which is mounted for rotation, a first parallelogram linkage constituted by two parallel links connecting the shoulder to an elbow, a second parallelogram linkage constituted by two parallel links connecting the elbow to a wrist, and a respective rotary fluidic motor, mounted on the shoulder and elbow, disposed to provide angular displacement of the first parallel linkage and the second parallel linkage in the same plane and with respect to the shoulder and the elbow respectively.

2. A robotic arm according to claim 1, in which a tensile spring is connected between the shoulder and the elbow.

3. A robotic arm according to either claim 1 or claim 2, in which each rotary fluidic motor comprises a body rigidly secured to the shoulder and elbow respectively and a shaft, rotatable relative to said body, keyed to a respective link.

4. A robotic arm substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   45 also carries two pairs of laterally extending studs which carry the side plates 8 and 8a.

   The inner section of the arm is constituted by two channel section struts 17 and 18. The strut 17 is pivoted to the shoulder at its lower end by means of a shaft 21 which has lock nuts 20 at each end, a bearing liner 22 and, around the dry bearing a spacer bush 40. The lower side ends of the strut 18 are secured by means of brackets 16 to drive clamp plates 15, 15a which are keyed to the shaft of a "kinetrol" rotary fluid actuator of which the casing is secured to the plates 8 and 8a. The shaft of the actuator carries a gear of 80 teeth in mesh with a gear of 20 teeth, which latter gear is mounted on a shaft extending between the plates 8 and 8a and drives a further, similar gear 10a which forms part of a shaft encoder 12 for providing an indication of the angular position of the strut 18 relative to the shoulder.

   Each of the channel section struts 17 and 18 is pivotally connected to the elbow, constituted by the plates 25 and 25a in the manner described for the lower end of the strut 17.

   Inside the inner section is a pair of springs 59, which are anchored at their uppper ends to a bracket 19 between the plates 25 and 25a.

   These springs provide tension between the elbow and the shoulder to counterbalance the arm. The springs are, at their lower ends, secured to a connector 61, by means of screws 60. The connector is connected by means of a turn buckle 62 to a T-bracket 41 carried on a short vertical strut extending upwardly from an end plate covering the upper end of the casing 45. A tensile spring may be connected between the elbow and the wrist to counterbalance the outer section.

   The outer section comprises two struts 30 and 37. The strut 30, which is of channel section, is pivotally secured to the apex of the elbow by means of a shaft 29, which carries a liner 32, a spacer bush encircling the liner, and lock nuts 27 at each end of the shaft 29.

   Each side panel of the strut 37 is secured to a respective drive arm, 39 and 39a, by means of a respective connecting bracket 78; the drive arms are connected to a "kinetrol" rotary actuator in a manner similar to the way in which the drive plates 15 and 15a are connected to the plates 8 and 8a.

   The wrist is principally constituted by a bracket 36 which carries shafts 33 each of which bears a spacer 34 for maintaining the side arms of the bracket separate. The shafts 33 act as pivots for the bracket about the outer ends of the struts 30 and 37.

   Appropriate pneumatic lines, not shown, provide pressure for the actuators, of which each is capable of continuous movement throughout its range of movement; it is preferable that each motor be not inherently adapted for incremental movement but that positioning be achieved by means of only external control valves and the micro-processor that governs them.

   WHAT WE CLAIM IS: 1. A robotic arm comprising a shoulder which is mounted for rotation, a first parallelogram linkage constituted by two parallel links connecting the shoulder to an elbow, a second parallelogram linkage constituted by two parallel links connecting the elbow to a wrist, and a respective rotary fluidic motor, mounted on the shoulder and elbow, disposed to provide angular displacement of the first parallel linkage and the second parallel linkage in the same plane and with respect to the shoulder and the elbow respectively.
2. 2. A robotic arm according to claim 1, in which a tensile spring is connected between the shoulder and the elbow.
3. 3. A robotic arm according to either claim 1 or claim 2, in which each rotary fluidic motor comprises a body rigidly secured to the shoulder and elbow respectively and a shaft, rotatable relative to said body, keyed to a respective link.
4. 4. A robotic arm substantially as hereinbefore described with reference to the accompanying drawings.