Robot arm space stabilizer

• US 4,949,026 A
• Filed: 12/07/1987
• Issued: 08/14/1990
• Est. Priority Date: 12/07/1987
• Status: Expired due to Fees

• Current Assignee: John A. Mead
• Original Assignee: John A. Mead
• Inventors: Mead, John A.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): MARTIN, DAVID S
• Application Number:
  US07/129,589
• Time in Patent Office: 981 Days
• Field of Search: 318/646, 318/10, 318/648, 318/649, 318/689, 318/567, 318/568.11, 318/568.16, 318/568.22, 74/5 F, 74/5.34, 74/5.4, 74/5.47
• US Class Current: 318/649
• CPC Class Codes: B25J 13/088 with position, velocity or acceleration sensors
• CPC Class Codes: B25J 17/0275 Universal joints, e.g. Hooke, Cardan, ball joints
• CPC Class Codes: Y10T 74/1254 by motor torque

Abstract

As a gyroscope is made to precess back and forth across a certain point; a servo, torquing about the axis causing precession, can stabilize the member containing the precession axis by maintaining the gyroscope at that point. In the subject invention, a signal generator measuring gyro movement on the precession axis, energizes the servo at the hinge between the member and its support toward the base and thus stabilizes said member against accidental oscillation of said support. After adding to the precession axis a velocity sensitive means for restraining gyro motion along with means for displacing the signal generator null, the servo will torque, and henceforth stabilize, the member to a new attitude signified by the angular displacement of the null. Momentum of the gyro wheel remembers its position in space and will return the member to its original null. In this manner, up to three orthogonally servoed robot arms may be space stabilized with attitude changes commanded remotely.

Claims

1. A system for maintaining the space attitude of a robot arm member supported by or hinged to a base undergoing random perturbations, comprising:

a torque motor mounted along said hinge where said arm is supported by said base;

a single-degree-of-freedom gyroscope whose first tilt or precession axis is housed perpendicular to its spin axle and, being formed between bearings carried within said arm, is oriented mutually perpendicular to said hinge;

first rotary differential transformer (RDT) mounted along said precession axis whose voltage output signifies amount and direction of angular inclination of said gyroscope wheel axle from its null position perpendicular to said hinge;

a velocity sensitive restrainer mounted along said precession axis to brake motion between said gyroscope and said arm and whose action, in combination with gyroscope wheel speed, determines said arm'"'"'s attitude adjustment per unit angular inclination change of said wheel axle from its normal position of perpendicularity to said hinge;

second rotary differential transformer (RDT) mounted accessible to the operator whose output is connected in tandem with that of said first RDT and whose rotor is indexed to the position where the null of said second RDT coincides with that of said first RDT such that the output of the two RDTs'"'"' network is affected by rotation at either and provides input to an amplifier for said torque motor;

whereby said arm is ordinarily maintained at a prescribed attitude by said torque motor responding to said first RDT'"'"'s error signal, and whereby said arm attitude may be adjusted in response to a command rotation of said second RDT rotor, while capable of being exactly reinstated by derotation of said rotor back to said indexed position.

2. A system as defined on claim 1, containing two or more robot arms, each having its attitude adjusted or controlled at its hinge or servoed axis adjoining toward the base.

3. In a system as defined in claim 1, including an addition of an electrical control to change gyroscope wheel speed for altering the attitude adjustment per unit angular inclination change of said wheel axle and thus per unit rotation of said second RDT rotor.