Robotic work tool and method for detecting tool damage or loss
A robotic work tool comprising a work tool ( 160 ), a tool damage detector ( 162 ) and a controller ( 110 ) for controlling the operation of the robotic work tool ( 100 ), the robotic work tool ( 100 ) being configured to detect that the work tool ( 100 ) is damaged or lost by detecting an irregularity utilizing the tool damage detector ( 162 ) and thereby determining that the work tool ( 160 ) is damaged or lost.
1. A robotic lawnmower comprising:
a work tool comprising a grass cutting device;
a cutter motor coupled to the work tool via a shaft the cutter motor being configured to drive the work tool to cut grass;
a tool damage detector configured to sense vibrations in the robotic lawnmower and detect a load exerted on the shaft, the load on the shaft being detected based on a measure of power delivered to the cutter motor or by sensing a torque on the shaft; and
a controller configured to:
control movement of the robotic lawnmower and a mowing operation of the robotic lawnmower;
determine that the work tool is damaged or lost based on the vibrations in the robotic lawnmower sensed by the tool damage detector and the load exerted on the shaft by:
determining that an increase in vibrations over a vibration threshold level is occurring and a decrease in the load exerted on the shaft has occurred,
causing the robotic lawnmower to arrest or stop movement, and
determining that the increase in vibrations is present with the movement of the robotic lawnmower arrested or stopped indicating that the work tool is damaged or lost;
record a position of the robotic lawnmower in response to detecting the damage to or loss of the work tool; and
discontinue the mowing operation in response to detecting the damage to or loss of the work tool.
2. The robotic lawnmower of claim 1 , wherein the controller is further configured to provide an indication including coordinates for the position where the damage or loss of the work tool was detected via a user interface or a communication interface also comprised in the robotic lawnmower.
3. The robotic lawnmower of claim 1 , wherein the controller is further configured to cause the robotic lawnmower to return to a servicing station in response to detecting damage or loss of the work tool.
4. The robotic lawnmower of claim 1 , wherein the tool damage detector is configured to sense vibrations in the robotic lawnmower as a whole, on the shaft driving the work tool, or on the cutter motor.
5. The robotic lawnmower of claim 1 , wherein the tool damage detector is further configured to detect the decrease in the load exerted on the shaft below a threshold load for at least a predetermined duration of time.
6. The robotic lawnmower of claim 1 , wherein the tool damage detector is further configured to detect the decrease in the load exerted on the shaft below a threshold load, the threshold load being a threshold rate of decrease of the load exerted on the shaft.
7. The robotic lawnmower of claim 1 , wherein controller is further configured to issue an error signal in response to the tool damage detector detecting that the work tool is damaged or lost.
8. A robotic lawnmower comprising:
a work tool comprising a grass cutting device;
a tool damage detector configured to sense vibrations in the robotic lawnmower; and
a controller configured to
control a mowing operation of the robotic lawnmower,
determine that the work tool is damaged or lost based on the vibrations in the robotic lawnmower sensed by the tool damage detector by determining that an increase in vibrations over a threshold level is occurring, causing the robotic lawnmower to arrest or stop movement, and determining that the increase in vibrations is present with the movement of the robotic lawnmower arrested or stopped indicating that the work tool is damaged or lost; and
record a position of the robotic lawnmower in response to determining that the work tool is damaged or lost.
9. The robotic lawnmower of claim 8 , wherein the controller is further configured to provide an indication including coordinates for a position where damage or loss of the work tool was detected via a user interface or a communication interface also comprised in the robotic lawnmower.
10. The robotic lawnmower of claim 8 , wherein the controller is configured to determine that the increase in the vibrations are over the threshold level for at least a predetermined duration of time.
11. The robotic lawnmower of claim 8 , wherein the controller is further configured to determine that the increase in vibrations is over the threshold level, the threshold level being a threshold rate of increase in vibrations.
12. The robotic lawnmower of claim 8 , wherein the tool damage detector is configured to sense vibrations in a motor shaft of the work tool.
13. The robotic lawnmower of claim 8 , wherein the tool damage detector is configured to sense vibrations in an external cover of the robotic lawnmower.
14. The robotic lawnmower of claim 8 , wherein the controller is further configured to determine a position of the robotic lawnmower based at least in part on deduced reckoning navigation.