Vision-Based Robot Arm Joint Sensing Without Encoders
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Solution Overview
Problem
Current sensor systems for monitoring and controlling robot arms lack precision and efficiency in determining the pose and movement parameters of kinematic chains, especially in unstructured environments, and require complex wiring and multiple sensor modules.
Innovation Solution
A sensor system comprising high-resolution imaging sensors, such as cameras, connected to a computing unit that analyzes characteristic features to determine the pose and movement parameters of kinematic chain elements, allowing for visual servoing and reduced reliance on traditional position and velocity sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional position sensors and velocity sensors are used in each joint, then measurement precision is improved, but device complexity increases due to multiple sensor modules and complex wiring
Solution Approach 1:
The patent extracts the measurement function from individual joint sensors and relocates it to an external imaging sensor system. The imaging sensor captures images of characteristic features on the robot arm, and a computing unit calculates joint positions from these images, eliminating the need for physical sensors in each joint.
Solution Approach 2:
The patent replaces mechanical position sensors (encoders, potentiometers) with an optical measurement system. Instead of mechanical sensors directly measuring joint angles, the system uses imaging sensors to capture visual information and computationally derives joint positions from image data.
2Manufacturing precision
If high-precision position sensors are installed in each joint, then manufacturing precision is improved, but ease of manufacture deteriorates due to complex assembly and wiring
Solution Approach 1:
The patent removes position sensors from the robot arm joints, eliminating the need for precise sensor installation and wiring during assembly. Only simple characteristic features need to be provided on the robot arm components, which can be done during standard manufacturing without specialized sensor integration.
3Reliability
If multiple sensor modules with complex wiring are used, then reliability is improved through redundant measurements, but ease of operation deteriorates due to maintenance complexity
Solution Approach 1:
The patent extracts all position measurement functionality from the robot arm itself and consolidates it into an external imaging sensor and computing unit. This centralized external system is easier to maintain than distributed joint sensors, as it eliminates wiring through the arm and allows the arm to be serviced independently of the measurement system.
Data Source
AI summary
A method for determining the joint positions of a kinematic chain uses only an imaging sensor and a computing unit. Characteristic features on the links and joints of the kinematic chain are identified and the joint positions are calculated from these visual measurements. The robot can be controlled without the use of joint encoders. A sensor system for monitoring the status of a kinematic chain includes a computing unit and an imaging sensor. The imaging sensor may be mounted to the kinematic chain or in the surroundings of the kinematic chain and monitors the kinematic chain and/or the surroundings of the kinematic chain. The computing unit determines a pose and/or movement parameters of at least one element of the kinematic chain by analyzing an output signal of the imaging sensor, in particular by analyzing characteristic features and determines a rotational joint position by analyzing the characteristic features.