Manipulability

How to configure the Manipulability detector and setup gain scheduling.

2 minute read

Manipulability

The Manipulability indicates how close the robot to a singular pose is. If the robot is in a singular pose, the manipulability is 0. Switching to Manual Cartesian in a singular pose could lead to position jump. To avoid this you can enable and adjust the Manipulability Detector such that you are never able to start your robot in manual cartesian mode.

Actual Manipulability

The actual manipulability can be found via the DESK-tool in the path:root/ManipulatorControl/manipulabilityDetector/input. To understand the relation between robot pose and manipulability, you should switch the robot to manual joint mode and open the actualManipulability. Move each joint separately, in order to figure out which joints have influence on the manipulability of your robot. Try to understand how the robot behaves and adjust the Actual Manipulability Gain Lookup table such, that you have a smooth transition.

Warning

Changing Manipulability Gains can lead to potential robot jumping, always adjust the parameters in simulation mode! When tested in Simulation mode and the robot does not jump, you can switch to production mode.

Configure the manipulability detector via the GUI

You can configure the manipulability detector for the robot through the GUI under the Alarms Tab.

You can enable or disable the manipulability detector.
Define the Low threshold value. If the input exceeds the defined threshold value a Warning is triggered.
Define the Too Low threshold value . If the input exceeds the defined threshold value a Emergency Stop is triggered.
Save Configuration
- Press Save Settings to store all your changes.

Configure the manipulability detector via the DESK-tool

GUI parameter:	Description:	Desk Parameter:
Manipulability Detector
Input	Acceleration position value	root/ManipulatorControl/manipulabilityDetector/input
Enable	Enable switch	root/ManipulatorControl/manipulabilityDetector/enable
Threshold Value
TooLow	Lower emergency stop threshold	root/ManipulatorControl/manipulabilityDetector/tooLow
Low	Lower warning threshold	root/ManipulatorControl/manipulabilityDetector/Low
Trigger Signal
isTooLow	Lower emergency stop trigger	root/ManipulatorControl/manipulabilityDetector/isTooLow
isLow	Lower warning trigger	root/ManipulatorControl/manipulabilityDetector/isLow

Manipulability Gain Scheduling

The actual manipulabilityGain defines, the gain applied to the movement, if the gain = 0 the rate of movement = 0. With the manipulabilityGainLookup you can define the rate of deceleration towards a singular pose.

Desk-Tool Path: root/ManipulatorControl/manipulabilityGainLookup

Parameter	Description
input	The input is linked to the `actualManipulability`.
numPoints	The `numPoints` indicate how many table values are used.
output	Indicates the `manipulabilityGain` as result of the lookup table.
x	In the x table, you define the `actual manipulability` for each range xn, x(n+1), …
y	In the y table you define the `manipulabilityGain` based on the actual manipulability range yn, y(n+1), …