Operator´s Manual
1000-095-071-EN Rev. 1.1
OMNERA®
2020-09-14
Page 41
2.12 Safety functions
2.12.1 System
2.12.1.1 Collision detection
Input check
To secure that the system is operational and fully functional the system performs a self test
at start up. The system checks that no inputs are activated during start up. In that case the
system takes actions to inhibit the function to be used. If a safety related input, such a switch
in the foot control or in the handle is active, the system stops sending the watchdog signal to
the trig relay and the power to the motor is cut.
Motorized movements
Motorized movements are performed using a PID-controller with position feed-back. An ab-
solute encoder or a potentiometer or both a potentiometer and a quadrature encoder may be
used as position transducer. The speed of the movement follows a trapezoid shaped curve.
The movement is stopped when a collision or a faulty position transducer is detected. A colli-
sion is detected if the control error is too large. The control error is defined as the difference
between the set point and the actual position. The set point is given by the ramp generation
and the actual position is given from the position transducer. The maximum allowed differ-
ence is set by a parameter.
Z Column
A guard plate installed on top of the column, registers vertical pressure on the column, for in-
stance a vertical impact.
When the pressure exceeds the trig level vertically, all movements are stopped and a warn-
ing message is displayed. To be able to release the pressure, a movement in the opposite di-
rection is allowed. When the pressure on the column has returned to normal, see Fig. 2-20
the warning message is removed and motorized movements are allowed
again.
A
B
B
C
D
Fig. 2-20 Collision detection
A Zero force level
B Hysteresis
C Upper trig level
D Lower trig level
