Overturn Prevention Control Device for Bicycle Robots
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Solution Overview
Problem
Existing two-wheel vehicles and robots struggle to maintain balance during halts or low-speed movements, as existing inclination detection methods are inaccurate, especially on uneven surfaces, and integrate noise, leading to potential overturning.
Innovation Solution
An overturn prevention control device using an angular velocity sensor, motor, rotation sensor, and inertial rotor, which estimates inclination angles relative to a balanced state without direct detection, employing reaction torque to correct inclination, and includes means to generate torque commands and compensate for external torques, allowing precise control of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical sensor is used to detect inclination by receiving reflected light, then the device can detect inclination on flat surfaces, but it cannot accurately detect inclination on uneven surfaces or when the floor is absent
Solution Approach 1:
The patent replaces the optical sensor system with an angular velocity sensor (gyro sensor) that detects inclination through mechanical rotation detection. The angular velocity sensor measures the rotation rate of the vehicle body, and the control unit integrates this data to calculate inclination angle, providing accurate detection regardless of surface conditions.
Solution Approach 2:
The patent introduces an angular velocity sensor as an intermediary measurement device that indirectly detects inclination through motion detection rather than direct optical measurement. This intermediary approach allows the system to infer inclination state without being affected by surface reflectivity or presence.
2Ease of operation
If the vertical direction is used as the reference position for inclination detection, then the detection method is simple, but the vehicle may be unable to maintain balance when the balanced state is not vertical
Solution Approach 1:
The patent implements a feedback control system where the control unit continuously monitors the inclination angle calculated from angular velocity data and compares it with the desired balanced state. The system then adjusts the flywheel rotation to counteract detected inclination, creating a closed-loop control that adapts to the actual balanced state rather than assuming a fixed vertical reference.
3Measurement precision
If integration of angular velocity output is used to estimate inclination, then inclination can be estimated from motion data, but noises or offsets accumulate and estimation cannot continue
Solution Approach 1:
The patent employs periodic calibration where the control unit periodically resets the integrated inclination value when the vehicle is detected to be in a balanced state (angular velocity near zero). This periodic reset prevents noise and offset accumulation while maintaining accurate inclination estimation during active balance control.
4Measurement precision
If an inclination sensor using a weight is used to detect inclination, then the device can detect inclination from gravitational force, but it cannot detect the inclination corresponding to the balanced state and has poor responsivity
Solution Approach 1:
The patent replaces the weight-based inclination sensor with an angular velocity sensor system that uses rotational motion detection and mathematical integration to estimate inclination. This substitution provides both the ability to detect inclination and the responsiveness needed for dynamic balance control, as angular velocity sensors have no moving mass and respond instantaneously to motion changes.
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 enables accurate and responsive detection and control of inclination angles, preventing overturning even on uneven surfaces and during low-speed movements, with improved responsivity and stability compared to traditional methods.
Implementation Method 1
an angular velocity sensor which detects an angular velocity of the body
Implementation Method 2
correcting the inclination of the body by rotating an inertial rotor using a motor and by employing a reaction torque which occurs when the inertial rotor is rotated
Implementation Method 3
an inertial rotor coupled to a rotating shaft of the motor
Data Source
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AI summary
[Object] To provide an overturn prevention device capable of accurately estimating an inclination angle from a balanced state without accumulating noises and offsets and continuing estimation of an inclination angle and control for preventing overturning. [Solving Means] The overturn prevention control device includes a bicycle robot A capable of freely laterally inclining, an angular velocity sensor 7 mounted on the bicycle robot A such that a detection axis thereof faces in a substantially longitudinal direction of the bicycle robot A, a motor 9 mounted on the body such that a rotating shaft thereof faces in a substantially longitudinal direction of the body, a rotation sensor 10 that detects a rotational position or a rotational speed of the motor 9, and an inertial rotor 8 coupled to the rotating shaft of the motor 9. The overturn prevention control device corrects inclination of the bicycle robot A by rotating the inertial rotor 8 using the motor 9 and by employing a reaction torque occurring when the inertial rotor 8 is rotated. The overturn prevention control device further includes inclination angle estimating means for estimating an inclination angle relative to a balanced state from an angular velocity output ω1 from the angular velocity sensor 7 and a torque command τ0 to be supplied to the motor 9. The overturn prevention control device corrects inclination of the bicycle robot A using an estimate of the inclination angle.