Auto guide vehicle

Patent metadata

Field	Value
Publication number	US-11452256-B2
Application number	US-201816608559-A
Country	US
Kind code	B2
Filing date	Apr 27, 2018
Priority date	Apr 27, 2017
Publication date	Sep 27, 2022
Grant date	Sep 27, 2022

Abstract

An auto guide vehicle (20) that conveys a cart (10), wherein the auto guide vehicle (20) is provided with: a fluid pressure cylinder (22) that is able to be extended and retracted vertically, and that applies an upward pressing force to the floor surface of the cart (10); a fluid pressure supply device (70) that supplies a fluid to the fluid pressure cylinder (22); pressure regulating means (50) that regulates the fluid pressure of the fluid supplied from the fluid pressure supply device (70) to the fluid pressure cylinder (22); a control board (40) that outputs a fluid pressure command value to the pressure regulating means (50); and a pressure sensor (100) that detects the fluid pressure of the fluid supplied to the fluid pressure cylinder (22); wherein the control board (40) computes derivatives of the fluid pressure detected by the pressure sensor (100), estimates a timing at which the cart begins to leave the ground based on a pattern of the computed derivatives, and computes the command value by multiplying a coefficient less than one by the fluid pressure detected by the pressure sensor (100) at the estimated timing.

First claim

The invention claimed is:

1. An auto guide vehicle that conveys a cart by being ensconced in a standard space formed between a floor surface and a bottom surface of the cart, wherein the auto guide vehicle is provided with:
a fluid pressure cylinder that is able to be extended and retracted vertically, and that applies an upward pressing force to the bottom surface of the cart;
a fluid pressure supply device that supplies a fluid to the fluid pressure cylinder;
pressure regulating means that regulates the fluid pressure of the fluid supplied from the fluid pressure supply device to the fluid pressure cylinder;
a control board that outputs a fluid pressure command value to the pressure regulating means; and
a pressure sensor that detects the fluid pressure of the fluid supplied to the fluid pressure cylinder; wherein
the control board comprises:
a differentiation circuit that computes derivatives of the fluid pressure detected by the pressure sensor;
an estimation circuit that, based on a pattern of the derivatives computed by the differentiation circuit, estimates a timing at which the cart begins to leave the ground; and
a coefficient multiplication circuit that computes the command value by multiplying a coefficient less than one by the fluid pressure detected by the pressure sensor at the timing estimated by the estimation circuit.

2. The auto guide vehicle as in claim 1 , wherein:
the fluid pressure cylinder is formed by inserting a piston into a cylinder body so as to be able to move vertically, a receiving plate that contacts the bottom surface of the cart is provided on an upper end of a piston rod connected to the piston, and a proximity switch that switches on upon approaching to within a certain distance from the bottom surface of the cart is provided on the receiving plate; and
the estimation circuit estimates the timing at which the cart begins to leave the ground as being a time at which, with the proximity switch switched on, the derivative computed by the differentiation circuit has risen to a first prescribed value or higher, then fallen to a second prescribed value or lower.

3. The auto guide vehicle as in claim 1 , wherein the estimation circuit estimates the timing at which the cart begins to leave the ground as being a time at which, after a certain period of time has elapsed since the fluid pressure cylinder began to extend, the derivative computed by the differentiation circuit has risen to a first prescribed value or higher, then fallen to a second prescribed value or lower.

4. The auto guide vehicle as in claim 1 , wherein the estimation circuit estimates the timing at which the cart begins to leave the ground as being a time at which the derivative computed by the differentiation circuit becomes approximately zero.

5. The auto guide vehicle as in claim 1 , wherein:
when there are multiple fluid pressure cylinders, the pressure regulating means and the pressure sensor are respectively provided on respective fluid pressure cylinders; and
the coefficient multiplication circuit respectively outputs, to the respective pressure regulating means, command values corresponding to the pressures detected by the respective pressure sensors.

Assignees

• Meidensha Electric Mfg Co Ltd

Inventors

• Nishizawa Yasuhiro
• Ueno Toshiyuki
• Matsushita Yuya

Classifications

• F15B13/042

  operated by fluid pressure {(F15B13/0401, F15B13/0416 take precedence)} · CPC title

• B60Y2400/306

  Pressure sensors · CPC title

• B66F9/063 Primary

  Automatically guided · CPC title

• A01D34/008 Primary

  for automated or remotely controlled operation · CPC title

• B60D2001/005

  for carts, scooters or the like · CPC title