Quadruped Robot Foot-end Touchdown Detection via Kalman Filter
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Solution Overview
Problem
Current methods for detecting the foot-end touchdown state of quadruped robots are unreliable in rugged terrain, require complex sensor installations, and are costly due to high mechanical and material demands, especially when using barometric or pressure sensors.
Innovation Solution
A method utilizing the Kalman Filter to calculate foot-end touchdown probabilities based on foot-end height, knee torque, and gait schedule, eliminating the need for excess sensors at the foot end by integrating foot-end height and knee torque measurements with gait phase data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If barometric sensors or pressure sensors are deployed at the foot end to detect touchdown state, then measurement precision is improved, but device complexity and deployment cost increase due to high mechanical structure and material requirements
Solution Approach 1:
The patent replaces mechanical sensors (barometric sensors, pressure sensors) with an algorithm-based detection system. The touchdown state is determined by analyzing motor current characteristics and gait phase information through a judgment algorithm, eliminating the need for complex mechanical sensing structures at the foot end while maintaining detection accuracy
Solution Approach 2:
The patent introduces motor current as an intermediary parameter to indirectly detect touchdown state. Instead of directly measuring foot-end contact, the system monitors changes in motor current that occur during touchdown events and uses these changes to infer the touchdown state through algorithmic processing
2Measurement precision
If boolean sensors such as contact switches are deployed at the foot end to judge touchdown state, then measurement precision is improved, but reliability deteriorates due to short service life and installation difficulties
Solution Approach 1:
The patent replaces fragile mechanical boolean sensors (contact switches) with a software-based judgment algorithm that processes motor current and gait phase data. This eliminates the reliability issues associated with mechanical sensor wear, installation complexity, and short service life while maintaining accurate touchdown detection
Solution Approach 2:
The system uses the robot's own motor current measurements and gait schedule information to detect touchdown state, eliminating the need for separate sensing components. The motor system serves dual purposes: actuation and sensing, improving reliability by reducing component count
3Measurement precision
If barometric sensors or pressure sensors are deployed at the foot end to detect touchdown state, then measurement precision is improved, but ease of operation deteriorates due to difficult electrical wiring
Solution Approach 1:
The patent replaces sensor-based detection requiring electrical wiring with an algorithmic approach using existing motor current measurements. The touchdown detection leverages data already available from the motor control system, eliminating the need for additional wiring and simplifying system integration
4Device complexity
If gait schedule-based method is used to judge touchdown state, then device complexity is reduced, but reliability deteriorates in rugged or step terrain
Solution Approach 1:
The patent incorporates feedback from motor current measurements to adjust and refine touchdown detection. By continuously monitoring motor current characteristics during gait execution and comparing them against expected patterns, the system can reliably detect touchdowns even in rugged terrain where gait schedule predictions may be inaccurate
Solution Approach 2:
The system dynamically adapts touchdown detection by using real-time motor current data rather than relying solely on predetermined gait schedules. The judgment algorithm processes dynamic motor current variations to determine touchdown events, enabling reliable operation in varying terrain conditions
Data Source
AI summary
The disclosure relates to a method and system for detecting the foot-end touchdown of quadruped robot, including the following steps: S1. Calculating the foot-end height above ground of each leg, and calculating the foot-end height touchdown probability based on the foot-end height above ground of each leg; Calculating the knee torque touchdown probability based on the external torque of knee joint of each leg; S2. According to the foot-end touchdown probability calculated from the gait schedule, the foot-end height and the external torque of knee joint, using the Kalman Filter to obtain the final foot-end touchdown probability of four legs; Determining the foot-end touchdown state according to the foot-end touchdown probability of four legs. The disclosure may accurately estimate the touchdown state between the foot end and the ground based on the basic sensor and fusion algorithm of the quadruped robot without deploying excess sensors at the foot end, which can solve the problem of sensor wiring; the disclosure can still obtain reliable touchdown state even in rugged or step terrain.