Estimating motion of wheeled carts
First Claim
1. A navigation system for a human-propelled cart, the navigation system comprising:
- a magnetometer configured to determine a heading of the human-propelled cart;
a vibration sensor configured to measure vibration data of the human-propelled cart;
a communication system configured to communicate with a wheel of the human-propelled cart, the wheel comprising a brake configured to inhibit rotation of the wheel in response to receipt of a locking signal; and
a hardware processor programmed to;
estimate a speed of the human-propelled cart based at least in part on the vibration data from the vibration sensor, the hardware processor programmed to;
analyze a spectrum of the vibration data;
identify a first peak in the spectrum of the vibration data, the first peak associated with vibration data for vibrations associated with forward or rearward movement of the human-propelled cart;
determine a rotation rate of the wheel to be a harmonic frequency of the frequency of the first peak in the spectrum of the vibration data; and
estimate the speed based on the rotation rate and a circumference of the wheel; and
estimate a position of the human-propelled cart based at least in part on the estimate speed and the heading of the human-propelled cart.
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Accused Products
Abstract
Examples of systems and methods for locating movable objects such as carts (e.g., shopping carts) are disclosed. Such systems and methods can use dead reckoning techniques to estimate the current position of the movable object. Various techniques for improving accuracy of position estimates are disclosed, including compensation for various error sources involving the use of magnetometer and accelerometer, and using vibration analysis to derive wheel rotation rates. Also disclosed are various techniques to utilize characteristics of the operating environment in conjunction with or in lieu of dead reckoning techniques, including characteristic of environment such as ground texture, availability of signals from radio frequency (RF) transmitters including precision fix sources. Such systems and methods can be applied in both indoor and outdoor settings and in retail or warehouse settings.
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Citations
23 Claims
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1. A navigation system for a human-propelled cart, the navigation system comprising:
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a magnetometer configured to determine a heading of the human-propelled cart; a vibration sensor configured to measure vibration data of the human-propelled cart; a communication system configured to communicate with a wheel of the human-propelled cart, the wheel comprising a brake configured to inhibit rotation of the wheel in response to receipt of a locking signal; and a hardware processor programmed to; estimate a speed of the human-propelled cart based at least in part on the vibration data from the vibration sensor, the hardware processor programmed to; analyze a spectrum of the vibration data; identify a first peak in the spectrum of the vibration data, the first peak associated with vibration data for vibrations associated with forward or rearward movement of the human-propelled cart; determine a rotation rate of the wheel to be a harmonic frequency of the frequency of the first peak in the spectrum of the vibration data; and estimate the speed based on the rotation rate and a circumference of the wheel; and estimate a position of the human-propelled cart based at least in part on the estimate speed and the heading of the human-propelled cart. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A navigation method for a human-propelled wheeled cart, the method comprising:
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measuring, with a magnetometer, a magnetic heading of the human-propelled cart; measuring a spectrum of vibrations experienced by the human-propelled cart as the human-propelled cart travels over a surface; analyzing the spectrum of vibrations to determine a rotation rate of a wheel of the human-propelled cart; estimating a speed of the human-propelled cart based at least partly on the rotation rate of the wheel and a circumference of the wheel; and estimating a position of the human-propelled cart based at least partly on the estimated speed and the measured magnetic heading of the human-propelled cart. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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Specification