System for collision avoidance of rotary atomizer

• US 7,328,123 B2
• Filed: 02/09/2006
• Issued: 02/05/2008
• Est. Priority Date: 09/30/2002
• Status: Active Grant

• Current Assignee: Durr Systems Incorporated (Durr AG)
• Original Assignee: Durr Systems Incorporated (Durr AG)
• Inventors: Hooge, Sven, Wildermuth, Dietmar
• Primary Examiner(s): Barlow; John
• Assistant Examiner(s): TEIXEIRA MOFFAT, JONATHAN CHARLES
• Application Number:
  US11/350,434
• Publication Number:
  US 20060129348A1
• Time in Patent Office: 726 Days
• Field of Search: None
• US Class Current: 702/150
• CPC Class Codes: B25J 9/1674 characterised by safety, monitoring, diagnostic
• CPC Class Codes: G05B 19/4061 Avoiding collision or forbidden zones
• CPC Class Codes: G05B 19/4062 Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference
• CPC Class Codes: G05B 2219/37297 Two measurements, on driving motor and on slide or on both sides of motor
• CPC Class Codes: G05B 2219/37624 Detect collision, blocking by measuring change of velocity or torque
• CPC Class Codes: G05B 2219/37625 By measuring changing forces in a time window
• CPC Class Codes: G05B 2219/37632 By measuring current, load of motor
• CPC Class Codes: G05B 2219/39186 Flexible joint
• CPC Class Codes: G05B 2219/39355 Observer, disturbance observer
• CPC Class Codes: G05B 2219/41372 Force estimator using disturbance estimator observer
• CPC Class Codes: G05B 2219/42161 One model for load, one model for motor inertia

Abstract

A monitoring method for a drive system with a motor and a moving part driven by the motor. The movement of the driven part is monitored and the movement of the driving part is monitored and compared to recognize a collision between the driven part and another structure. Measurement of at least one drive-side motion quantity of the motor is taken and measurement of at least one driven-side motion quantity of the moving part is taken. The motion quantity can be a position, velocity or acceleration. A dynamic model is calculated based on predetermined or expected operational data and the drive side measured data. An error signal is generated when the motion quantity measured on the driven side varies from the dynamic model.

Claims

1. Monitoring method for a drive system of a robot, more specifically a painting robot, with a motor and a moving part driven by the motor, with the following steps:

measurement of at least one drive-side motion quantity (φ

_A1, ω

_A1) of the electric motor,

measurement of at least one driven-side motion quantity (x_M1, a_M1) of the moving part,

determination of an error signal (F<sub>STÖ

R</sub>) as a function of the motion quantities (φ

_A1, ω

_A1) of the electric motor measured on the drive side and of the motion quantities (x_M1, a_M1) of the moving part measured on the driven side;

measuring an armature current in an armature circuit of the electric motor;

measuring a voltage induced n the armature; and

calculating a comparison value (F_MODELL,1) from the armature current, the induced voltage and the at least one driven-side motion quantity (x_M1, a_M1).

2. The monitoring method set forth in claim 1 comprising the further steps of:

calculation of a first comparison value (F_L1) for a drive force or a drive moment of the motor with reference to the motion quantities (φ

_A1, ω

_A1) of the motor measured on the drive side;

comparison of the first comparison value (F_L1) with the second comparison value (F_MODELL,1); and

generation of the error signal (F<sub>STÖ

R</sub>) as a function of the comparison.

3. A drive system of a robot comprising:

a rotating first shaft;

a rotating second shaft engaged and disposed non-concentrically to the first shaft;

a first sensor constructed and arranged on the first shaft for measuring a first position value;

a second sensor constructed and arranged on the first shaft for measuring a first angular velocity value;

a third sensor constructed and arranged on the second shaft for measuring a second position value;

a fourth sensor constructed and arranged on the second shaft for measuring an acceleration value; and

a monitoring device that receives input from the first, second, third and fourth sensors and outputs an error signal;

a differentiator of the monitoring device for calculating a second angular velocity value of the second shaft as a time derivative of the second position value.

4. The drive system set forth in claim 3 further comprising a comparison force value calculated by the monitoring device from at least the first angular velocity value, the first position value, the second position value, and the second angular velocity.

5. The drive system set forth in claim 3 further comprising a first computational unit of the monitoring device for calculating a model-based force value from the second position value, the second acceleration value and the second angular velocity.

6. The drive system set forth in claim 5 further comprising a subtractor of the monitoring device for calculating the outputted error signal from the comparison force value and the model-based force value.

7. The drive system set forth in claim 6 further comprising an evaluation unit that receives the error signal from the monitoring device, the evaluation unit having an emergency stop output signal.

8. The drive system set forth in claim 7 further comprising:

a second computational unit of the evaluation unit for calculating a sliding mean value over time and associated with an output warning signal; and

a third computational unit of the evaluation unit for calculating the emergency stop output signal; and

wherein the third computational unit has a shorter averaging period than the second computational unit.

9. A drive system of a robot comprising:

an electric motor having a rotating first shaft having an angular first velocity;

a rotating second shaft having an angular second velocity that is different than the first velocity;

a gear connected between the first and second shafts;

the first shaft having at least one drive sensor for measurement of at least one drive-side motion quantity (φ

_A1, ω

_A1) of the first shaft;

the second shaft having at least one driven sensor for measurement of at least one driven-side motion quantity (x_M1, a_M1) of the second shaft;

a monitoring device that receives input signals from the at least one drive sensor and the at least one driven sensor; and

an error signal (F<sub>STÖ

R</sub>) calculated and outputted by the monitoring device

an evaluation unit for receipt of the error signal from the monitoring device the evaluation unit having a first computation unit for calculating a sliding mean value over time and associated with an output warning signal and a second computational unit of the evaluation unit for calculating an emergency stop output signal.

10. The drive system set forth in claim 9 wherein the second computational unit has a shorter averaging period than the first computational unit.

11. The drive system set forth in claim 9 wherein the first shaft is an armature.