Control of a robot manipulator upon contact with a person
A method of controlling a robot manipulator, the method including: providing a database containing body zones of a person, wherein each of the body zones is assigned a respective maximum permissible value of contact pressure value, determining a current or a future contact event of the robot manipulator involving the person, and determining a body zone of the person that is contacted, determining a reference position fixed relative to a body of the person, wherein the reference position indicates beginning of a spatial progression of depression of tissue of the person during the contact event with the person, and controlling the robot manipulator in an impedance-regulated manner, such that the reference position serves as a zero position of an artificial spring component of impedance regulation of the robot manipulator and a maximum permissible contact pressure is not exceeded as a limit value.
1. A method of controlling a robot manipulator, the method comprising:
providing a database containing body zones of a person, wherein each of the body zones is assigned a respective maximum permissible value of contact pressure;
determining a current or a future contact event of the robot manipulator involving the person, and determining a body zone of the person that is contacted;
determining a reference position fixed relative to a body of the person, wherein the reference position indicates beginning of a spatial progression of depression of a tissue of the person during the contact event with the person; and
controlling the robot manipulator in an impedance-regulated manner, such that the reference position serves as a zero position of an artificial spring component of impedance regulation of the robot manipulator and a maximum permissible contact pressure is not exceeded as a limit value.
2. The method of claim 1 , further comprising:
determining an edge geometry of a location on the robot manipulator coming into contact with the person; and
determining or adjusting the maximum permissible contact pressure depending on the edge geometry.
3. The method of any of claim 1 , wherein when the controlling in the impedance-regulated manner is carried out up to the maximum permissible contact pressure, the method comprises determining or reducing the maximum permissible contact pressure as a function of a speed of the location of the robot manipulator coming into contact with the person relative to the person.
4. The method of claim 1 , wherein the controlling in the impedance-regulated manner takes place such that a predetermined braking distance is not exceeded, when the tissue of the person is being depressed.
5. The method of claim 4 , wherein the method comprises determining the specified braking distance by a prediction of a distance from the reference position at which the maximum permissible contact pressure will be reached during the progression of the depression of the tissue of the person.
6. The method of claim 1 , wherein the controlling in the impedance-regulated manner is carried out by impedance regulation with respect to an earth-fixed coordinate system, such that a relative position vector between the location on the robot manipulator coming into contact with the person and the current reference position on the person is determined as a connection vector in the earth-fixed coordinate system.
7. The method of claim 1 , further comprising:
determining a degree of hardness and/or a modulus of elasticity of the location on the robot manipulator coming into contact with the person; and
determining or adjusting the maximum permissible contact pressure depending on the degree of hardness and/or modulus of elasticity.
8. The method of claim 1 , further comprising:
determining a temperature of a component with the location on the robot manipulator coming into contact with the person; and
determining or adjusting the maximum permissible contact pressure depending on the temperature.
9. The method of claim 1 , wherein the controlling in the impedance-regulated manner has a non-linear artificial spring component, such that with increasing deflection, a counterforce that increases disproportionately with the deflection acts on the robot manipulator.
10. A control unit to control a robot manipulator, the control unit comprising:
an interface to a database containing body zones of a person, wherein each of the body zones is assigned a respective maximum permissible value of contact pressure value; and
a computing unit configured to:
determine a current or a future contact event of the robot manipulator with the person, and to determine a body zone of the person that is contacted;
determine a reference position fixed relative to a body of the person, wherein the reference position indicates beginning of a spatial progression of depression of a tissue of the person during the contact event with the person; and
control the robot manipulator in an impedance-regulated manner, such that the reference position serves as the zero position of an artificial spring component of impedance regulation of the robot manipulator and a maximum permissible contact pressure is not exceeded as a limit value.
11. The control unit of claim 10 , wherein the computing unit is further configured to:
determine an edge geometry of a location on the robot manipulator coming into contact with the person; and
determine or adjust the maximum permissible contact pressure depending on the edge geometry.
12. The control unit of claim 10 , wherein when the control in the impedance-regulated manner is carried out up to the maximum permissible contact pressure, the computing unit is further configured to determine or reduce the maximum permissible contact pressure as a function of a speed of the location of the robot manipulator coming into contact with the person relative to the person.
13. The control unit of claim 10 , wherein the control in the impedance-regulated manner takes place such that a predetermined braking distance is not exceeded, when the tissue of the person is being depressed.
14. The control unit of claim 13 , wherein the computing unit is further configured to determine the specified braking distance by a prediction of a distance from the reference position at which the maximum permissible contact pressure will be reached during the progression of the depression of the tissue of the person.
15. The control unit of claim 10 , wherein the control in the impedance-regulated manner is carried out by impedance regulation with respect to an earth-fixed coordinate system, such that a relative position vector between the location on the robot manipulator coming into contact with the person and the current reference position on the person is determined as a connection vector in the earth-fixed coordinate system.
16. The control unit of claim 10 , wherein the computing unit is further configured to:
determine a degree of hardness and/or a modulus of elasticity of the location on the robot manipulator coming into contact with the person; and
determine or adjust the maximum permissible contact pressure depending on the degree of hardness and/or modulus of elasticity.
17. The control unit of claim 10 , wherein the computing unit is further configured to:
determine a temperature of a component with the location on the robot manipulator coming into contact with the person; and
determine or adjust the maximum permissible contact pressure depending on the temperature.
18. The control unit of claim 10 , wherein the control in the impedance-regulated manner has a non-linear artificial spring component, such that with increasing deflection, a counterforce that increases disproportionately with the deflection acts on the robot manipulator.