Servo-controlled mobility device

• US 4,156,835 A
• Filed: 05/29/1974
• Issued: 05/29/1979
• Est. Priority Date: 05/29/1974
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Whitney, Daniel E., Nevins, James L. Jr.
• Primary Examiner(s): Rubinson, Gene Z.
• Assistant Examiner(s): Indyk, Eugene S.
• Application Number:
  US05/474,342
• Time in Patent Office: 1,826 Days
• Field of Search: 318/561, 318/646, 318/648, 318/628, 235/150.1, 235/150.2, 235/150.25, 235/150.11 M, 364/105
• US Class Current: 318/561
• CPC Class Codes: B23P 19/00 Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation connecting metal parts or objects by metal-working procedures B21J, B23K; Tools or devices therefor so far as not provided for in other classes hand tools in general B25
• CPC Class Codes: B23P 19/105 using sensing means
• CPC Class Codes: B25J 17/0208 Compliance devices
• CPC Class Codes: B25J 19/02 Sensing devices
• CPC Class Codes: B25J 9/1628 characterised by the control loop
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G05B 19/402 characterised by control arrangements for positioning, e.g. centring a tool relative to a hole in the workpiece, additional detection means to correct position G05B19/19 takes precedence
• CPC Class Codes: G05B 19/4086 Coordinate conversions; Other special calculations
• CPC Class Codes: G05B 2219/33263 Conversion, transformation of coordinates, cartesian or polar
• CPC Class Codes: G05B 2219/35534 Conversion input data
• CPC Class Codes: G05B 2219/37344 Torque, thrust, twist, machining force measurement
• CPC Class Codes: G05B 2219/40087 Align hand on workpiece to pick up workpiece, peg and hole
• CPC Class Codes: G05B 2219/41248 Adapting characteristics of servo
• CPC Class Codes: G05B 2219/45083 Manipulators, robot

Abstract

A servo system includes a servo loop incorporating an articulated mechanical arm or other controllable element, resolved motion rate control apparatus or other coordinate transformation apparatus, and an accommodation branch. The transfer characteristics may be readily adjusted to constrain the controllable element to accomplish a desired task, and the accommodation branch transfer characteristics may be readily modified to accomplish the performance of many different tasks without modifications to other portions of the system.

Claims

1. Motion controlling apparatus comprising a first element controllable in at least two dimensions,

a servo loop including said controllable element which directs motions of said controllable element in an environment, said servo loop comprising

means for sensing interactions between said controllable element and said environment to provide sensory information, and

task-related transfer function means for utilizing said sensory information to control the magnitude and direction of the velocity of said controllable element, whereby said controllable element produces motion, force and torque appropriate to the accomplishment of a predetermined task.

7. Apparatus according to claim 1 wherein said servo loop includes

in series with said task-related transfer function apparatus,

additional transfer function and sensing apparatus adapted to convert sensed interactions between said controllable element and its enviroment into signals representative of said interactions.

2. Motion controlling apparatus comprising a first element controllable in at least two dimentions,

a first servo loop including said controllable element which directs motions of said controllable element in an environment,

a second servo loop including, in addition to the said first servo loop

means for sensing interactions between said controllable element and said environment to provide sensory information,

an accommodation branch including task-related transfer function means for utilizing said sensory information to constrain the performance of said first servo loop to a desired task by controlling the magnitude and direction of the velocity of said controllable element,

whereby said controllable element produces motion, force and torque appropriate to the accomplishment of a predetermined task.

8. Apparatus according to claim 2 wherein said second servo loop includes

in series with said task-related transfer function apparatus,

additional transfer function and sensing apparatus adapted to convert sensed interactions between said controllable element and its environment into signals representative of said interactions.

3. Motion controlling apparatus comprising a first element controllable in at least two dimension, said controllable element having at least two controllable degrees of freedom,

said controllable degree of freedom being expressed in a first coordinate system,

said controllable element having at least two output motions,

said output motions being expressed in a second coordinate system,

a servo loop including said controllable element,

means for performing transformations between said first coordinate system and said second coordinate system,

said servo loop directing motions of said controllable element in an enviornment,

said servo loop comprising

means for sensing interactions between said controllable element and said environment to provide sensory information, and

task-related transfer function means for utilizing said sensory information to control the magnitude and direction of the velocity of said controllable element of said controllable element, whereby said controllable element produces motion, force and torque appropriate to the accomplishment of a predetermined task.

5. Apparatus according to claim 3 wherein said servo loop includes

resolved motion rate control transfer function apparatus

adapted to accomplish said transformation between said first coordinate system and said second coordinate system

to provide input commands to the said controllable element proportioned according to the relationship between input motions, forces and torques expressed in said first coordinate system, and desired output motions, forces and torques expressed in said second coordinate system,

whereby a command proportioned to desired output motions, forces and torques will be converted to commands which will cause said controllable element to perform said desired motions, forces and torques.

9. Apparatus according to claim 3 wherein said sensing apparatus is located on said controllable element and acts to sense interactions between said controllable element and said environment into signals representative of said interaction,

said signals being processed by transfer function apparatus in said servo loop

so as to express said signals in said second coordinate system.

11. Apparatus according to claim 3 wherein said sensing apparatus is located in said environment, and acts to sense interactions between said controllable element and said environment into signals representative of said interaction,

said signals being processed by transfer function apparatus in said servo loop so as to express said signals in said second coordinate system.

4. Motion controlling apparatus comprising a first element controllable in at least two dimensions,

said controllable element having at least two controllable degrees of freedom, said controllable degrees of freedom being expressed in a first coordinate system,

said controllable element having at least two output motions,

said output motions being expressed in a second coordinate system,

a first servo loop including said controllable element

means for performing transformations between said first coordinate system and said second coordinate system,

said first servo loop directing motions of said controllable element in an environment,

a second servo loop including, in addition to the said first servo loop

means for sensing interactions between said controllable element and said environment to provide sensory information,

an accommodation branch including task-related transfer function means for utilizing said sensory information to constrain the performance of said first servo loop to a desired task by controlling the magnitude and direction of the velocity of said controllable element,

whereby said controllable element produces motion, force and torque appropriate to the accomplishment of a predetermined task.

6. Apparatus according to claim 4 wherein said second servo loop includes

resolved motion rate control transfer function apparatus

adapted to accomplish said transformation between said first coordinate system and said second coordinate system to provide input commands to the said controllable element

proportioned according to the relationship between input motions, forces and torques expressed in said first coordinate system, and desired output motions, forces and torques expressed in said second coordinate system,

whereby a command proportioned to desired output motions, forces and torques will be converted to commands which will cause said controllable element to perform said desired motions, forces and torques.

10. Apparatus according to claim 4 wherein said sensing apparatus is located on said controllable element and acts to convert sensed interactions between said controllable element and said environment into signals representative of said interaction,

said signals being processed by transfer function apparatus in said second servo loop so as to express said signals in said second coordinate system.

12. Apparatus according to claim 4 wherein said sensing apparatus is located in said environment, and

acts to convert sensed interactions between said controllable element and said environment into signals representative of said interaction,

said signals being processed by transfer function apparatus in said second servo loop so as to express said signals in said second coordinate system.