Method and device for controlling a robot during co-activity

Patent metadata

Field	Value
Publication number	US-11192251-B2
Application number	US-201615779516-A
Country	US
Kind code	B2
Filing date	Nov 28, 2016
Priority date	Nov 26, 2015
Publication date	Dec 7, 2021
Grant date	Dec 7, 2021

Abstract

A method for controlling the operation of a robot within a system. The system includes the robot and sensors to analyze the concentric environment of the system. The sensors include a contact sensor, a proximity sensor and a vision and location sensor. For each of the axes of the robot, a maximum allowable force value is obtained. If the force on one of the axes of the robot is greater than the maximum value, the robot is stopped in its position. A concentric monitoring space or a security space is obtained as a function of the speed of the robot. The environment of the robot is monitored by the sensors. If the intrusion of an object is detected in the safe space of the robot, the maneuvering speed of the robot is gradually decreased to a safe speed. The process is repeated for the next axis of the robot.

First claim

The invention claimed is:

1. A method for controlling an operation of a robot within a system comprising the robot and sensors to analyze a concentric environment of the robot, the sensors comprise a contact sensor, a proximity sensor and a vision and location sensor, the method comprises steps of:
a) obtaining for each axis of the robot, a maximum allowable force value;
b) stopping the robot in its position in response to a determination that a force on one of the axes of the robot is greater than the maximum allowable force value;
c) obtaining a security space as a function of a speed of the robot;
d) monitoring the concentric environment of the robot by the sensors;
e) gradually reducing the speed of the robot to a safety speed in response to a detection of an intrusion of an intrusive object in the security space of the robot; and
f) repeating steps a)-e); and
wherein temporal position commands σ(t) of the robot are delivered by a robot controller as a function of a theoretical trajectory s(t) according to a temporal control interval Δt corresponding to a servo frequency 1/Δt, so that under nominal conditions of operation σ(t)=s(t); and wherein the speed reduction during step e) is achieved by introducing a virtual time so that σ(t+Δt)=s(t+k·Δt) where k≤1.

2. The method according to claim 1 , further comprising, between steps e) and f), steps of:
g) obtaining a position of the intrusive object in the security space of the robot;
h) computing an avoidance path by a processor and a robot controller; and
i) moving the robot along the avoidance path.

3. The method according to claim 2 , further comprising, between steps i) and f), step j) of determining a modified path away from the intrusive object in response to a detection of a proximity of the intrusive object by the proximity sensor.

4. The method according to claim 3 , comprising, between steps j) and f), step k) of generating the modified path away from the intrusive object in response to a detection of a contact with the intrusive object by the contact sensor.

5. The method according to claim 1 , further comprising, between steps e) and f), step 1 ) of placing the robot in a state of gravity compensation in response to a detection of a proximity of the intrusive object by the proximity sensor or to a detection of a contact with the intrusive object by the contact sensor.

6. The method as claimed in claim 1 , wherein robot motion commands are generated by the robot controller to deliver temporal position commands σ(t); and further comprising modifying an interpolation time interval of the robot without modifying a servo frequency to gradually reduce the speed of the robot.

7. The method according to claim 3 , wherein the robot is configured to move to a target position following a theoretical path; and wherein the modified path is obtained by bending the theoretical path in proportion to a vector of repulsion, oriented along a detection axis of the proximity sensor and of an intensity proportional to information delivered by the proximity sensor.

8. The method according to claim 4 , wherein the robot is configured to move to a target position following a theoretical path; and wherein the modified path is obtained by bending the theoretical path in proportion to a vector of repulsion, oriented along a detection axis of the contact sensor and of an intensity proportional to information delivered by the contact sensor.

9. The method according to claim 2 , wherein the robot is configured to move toward a target position along a theoretical path; and wherein the step of computing the avoidance path comprises steps of: generating a plurality of theoretical random positions in the security space of the robot; eliminating the random positions colliding with the intrusive object, and determining a shortest path to reach the target position among the remaining random positions.

Assignees

• Inst De Rech Tech Jules Verne
• Centre Nat Rech Scient
• Univ Nantes

Inventors

• Chevallereau Christine
• Girin Alexis
• Long Philip

Classifications

• B25J9/1674 Primary

  characterised by safety, monitoring, diagnostic · CPC title

• B25J9/1651

  acceleration, rate control · CPC title

• B25J9/1697

  Vision controlled systems · CPC title

• B25J9/1676 Primary

  Avoiding collision or forbidden zones · CPC title

• G05B2219/49201

  Variable load, slide friction, irregular machine guides · CPC title