Method and device for controlling a robot during co-activity

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.