Robot Joint Structure Backlash Stabilization via Tension Spring Biasing
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Solution Overview
Problem
Existing robot joint structures face challenges in stabilizing operations due to unexpected moments and vibrations caused by backlash in the joint portions, which are difficult to prevent with current mechanisms.
Innovation Solution
A control device is implemented with a processor that detects sensor values, applies an offset value to compensate for differences in critical situations, and uses a tension spring to provide rotational biasing forces, stabilizing the joint structure by maintaining consistent backlash positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanism for transmitting driving force to the joint portion is used, then the robot can perform various operations, but backlash occurs in the joint portion causing unexpected moments and vibrations
Solution Approach 1:
The patent applies biasing means (springs) to intentionally introduce elastic forces that counteract the harmful effects of backlash. The springs are configured to apply preloading forces that keep gear teeth in constant contact, converting the potential harm of backlash into a controlled elastic deformation that eliminates play while allowing the gear mechanism to function.
Solution Approach 2:
The patent changes the mechanical parameters of the joint structure by introducing spring elements with specific stiffness and preloading forces. This modifies the force-displacement characteristics of the joint, transforming the rigid gear interface into a compliant interface that maintains continuous contact while accommodating manufacturing tolerances and reducing backlash effects.
2Reliability
If biasing means are added to control backlash, then operation stability improves, but device complexity increases
Solution Approach 1:
The biasing means serve multiple functions simultaneously: they apply preloading forces to eliminate backlash, provide damping during gear engagement, and maintain constant contact between gear teeth. This multi-functionality reduces the need for separate mechanisms for each function, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The spring elements act as intermediary components between the driving force and the joint portion. Rather than directly modifying the gear teeth or adding complex active control systems, the springs mediate the force transmission, providing a simple passive mechanism to control backlash that integrates smoothly with existing gear structures.
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 solution effectively stabilizes robot operations by controlling backlash in joint portions, preventing unexpected moments and vibrations, and ensuring accurate movement and positioning, particularly in bipedal walking and arm movements.
Implementation Method 1
joint structure (160) including: a joint portion (130)... biasing means configured to apply, to the second part (130B), a rotational biasing force about the rotational axis X
Data Source
AI summary
According to a certain aspect of the present invention, a control device for a robot is provided. The control device includes a processor configured to implement: a function of obtaining a signal indicating a detected value of a sensor detecting a state quantity of the robot; and a function of, in converting the detected value to an estimated value of the state quantity according to a conversion function obtained by calibration of the sensor, applying an offset value compensating for a difference between the estimated value and the actual state quantity in a critical situation in operation of the robot.