Robot Bumper Contact Sensing for Precise Obstacle Detection
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Solution Overview
Problem
Existing mobile robots rely on mechanical switches for obstacle detection, which provide limited information about the force and location of contact, leading to inefficient navigation and increased risk of getting stuck between obstacles.
Innovation Solution
The use of capacitive, inductive, or Hall effect sensors mounted on a bumper that detect movement relative to the robot's chassis, generating signals proportional to the distance between plates, allowing for the determination of force attributes such as location, magnitude, and duration, enabling more precise navigation and reduced risk of entrapment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical switches are used for obstacle detection, then the device complexity is reduced, but the measurement precision and information about contact force and location are insufficient
Solution Approach 1:
The patent replaces mechanical switches with capacitive sensors that use electrical fields instead of mechanical contact. The capacitive sensor includes a movable plate coupled to the bumper and a stationary plate, detecting bumper movement through changes in capacitance rather than mechanical switch actuation. This substitution provides continuous analog signals about contact force and location while reducing mechanical wear and improving measurement precision.
Solution Approach 2:
The patent changes the detection parameter from binary mechanical switch states to continuous capacitive values. The capacitive sensor outputs analog signals that vary continuously with bumper displacement, providing precise measurement of contact force magnitude and location. The controller processes these varying signals to determine contact attributes, transforming discrete mechanical detection into continuous electrical parameter measurement.
2Productivity
If mechanical switches provide binary contact indication, then the device complexity is low, but the robot navigation efficiency deteriorates due to limited information
Solution Approach 1:
The patent implements feedback by continuously monitoring capacitive sensor signals during bumper movement. The controller receives real-time analog signals from the capacitive sensor, processing this feedback information to determine contact force magnitude, direction, and location. This continuous feedback enables dynamic navigation adjustments, allowing the robot to respond appropriately to different contact scenarios rather than relying on simple binary contact detection.
Solution Approach 2:
The patent introduces the capacitive sensor as an intermediary between the mechanical bumper and the control system. The sensor converts mechanical bumper displacement into electrical signals that preserve information about contact force and location. This intermediary transformation enables rich information transmission from the physical contact event to the navigation controller, bridging the gap between mechanical interaction and digital processing.
3Reliability
If binary contact detection is used, then the manufacturing precision requirements are low, but the robot gets stuck more frequently between obstacles
Solution Approach 1:
The patent employs dynamic measurement by detecting changes in capacitive values during bumper movement rather than relying on fixed mechanical switch positions. The movable plate moves with the bumper, and the controller processes the dynamic signal variations to determine contact characteristics. This dynamic approach compensates for manufacturing tolerances in plate alignment, as the system measures relative displacement and changes rather than absolute positions.
Solution Approach 2:
The patent performs preliminary calibration of the capacitive sensor system during manufacturing or initial operation. The controller characterizes the relationship between capacitive signal variations and bumper displacement for each specific sensor configuration. This preliminary action creates a calibration map that accounts for individual manufacturing variations, enabling accurate contact force and location determination despite tolerances in sensor plate alignment and bumper geometry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The sensor system provides high sensitivity for accurate detection of forces, allowing the robot to adjust its path effectively and reduce the number of visible components, improving reactivity and avoiding obstacles with greater precision.
Implementation Method 1
each sensor may be a capacitive sensor having one plate movably mounted so that the plate moves along with the bumper relative to the chassis, and another plate mounted so that it is stationary relative to the chassis. Movement of one plate relative to another, due to the movement of the bumper, causes the capacitive sensor to output an electrical signal having a magnitude or value proportional to the distance between the plates.
Implementation Method 2
The sensor can include a Hall effect sensor, the first portion of the sensor can include a winding of the inductive sensor, the second portion can include a core of the inductive sensor
Data Source
AI summary
A robot includes a body and a bumper. The body is movable relative to a surface and includes a first portion of a sensor. The bumper is mounted on the body and movable relative to the body and includes a backing and a second portion of the sensor. The backing is movable relative to the body in response to a force applied to the bumper. The second portion of the sensor is attached to the backing and movable with the backing relative to the first portion of the sensor in response to a force applied to the bumper. The sensor is configured to output an electrical signal in response to a movement of the backing. The electrical signal is proportional to an amount of displacement of the second portion relative to the first portion.