Pushcart

Patent metadata

Field	Value
Publication number	US-9845101-B2
Application number	US-201715443086-A
Country	US
Kind code	B2
Filing date	Feb 27, 2017
Priority date	Sep 3, 2014
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

A pushcart includes a left wheel, a right wheel, a left wheel driver, a right wheel driver, a control unit, a left wheel rotary encoder, and a right wheel rotary encoder. The left wheel driver rotates the left wheel. The right wheel driver rotates the right wheel. The left wheel rotary encoder detects a rotational angle of the left wheel. The right wheel rotary encoder detects a rotational angle of the right wheel. The pushcart performs feedback control on angular velocities of the left wheel and the right wheel at least using an integral operation. The control unit calculates a weighted average of an integral element with respect to the angular velocity of the left wheel and an integral element with respect to the angular velocity of the right wheel, and then separately controls the left wheel driver and the right wheel driver based on the weighted average.

First claim

The invention claimed is:

1. A pushcart comprising:
a main body;
a first wheel provided at a left side of the main body;
a second wheel provided at a right side of the main body;
a first wheel driver that rotates the first wheel about a rotational shaft of the first wheel;
a second wheel driver that rotates the second wheel about a rotational shaft of the second wheel;
a controller that separately controls the first wheel driver and the second wheel driver; and
a wheel angular velocity detector that detects an angular velocity of each of the first wheel and the second wheel about the respective rotational shafts,
wherein the controller performs a feedback control using at least an integral operation on the angular velocities of the first wheel and the second wheel about the rotational shafts thereof,
wherein the controller calculates a weighted average of an integral element with respect to the angular velocity of the first wheel about the rotational shaft of the first wheel and an integral element with respect to the angular velocity of the second wheel about the rotational shaft of the second wheel, and
wherein the controller separately controls the first wheel driver and the second wheel driver based on the weighted average.

2. The pushcart according to claim 1 ,
wherein the controller makes the weighted average approach an arithmetic average as a difference between an angular velocity command value of the first wheel and an angular velocity command value of the second wheel decreases.

3. The pushcart according to claim 1 , further comprising:
a braking operation reception portion that receives a braking operation from a user with respect to the first wheel and the second wheel,
wherein the controller makes the weighted average approach an arithmetic average as the braking operation increases.

4. The pushcart according to claim 1 , further comprising:
a turn angular velocity command reception portion that receives an operation to turn the pushcart from a user, and outputs a turn angular velocity command value,
wherein the controller separately controls the first wheel driver and the second wheel driver based on the angular velocity command value.

5. The pushcart according to claim 1 , further comprising:
a main body rotary encoder that detects a pitch angle of the pushcart,
wherein the controller separately controls the first wheel driver and the second wheel driver based on the pitch angle.

6. The pushcart according to claim 1 , wherein the integral elements correspond to:
0.5· K I ∫ωe 1( t ) dt+ 0.5· K I ∫ωe 2( t ) dt

wherein K I is an integral gain, and ωe 1 and ωe 2 are angular velocity deviation values of the left and right wheels, respectively.

7. The pushcart according to claim 1 , wherein the integral elements correspond to:
a ( t )· K I ∫ωe 1( t ) dt +(1−α( t ))· K I ∫ωe 2( t ) dt

wherein a(t) is a weight of in the weighted average calculation, K I is an integral gain, ωe 1 is an angular velocity deviation value of the wheel corresponding to the integral element, and ωe 2 is an angular velocity deviation value of the other wheel.

Assignees

• Murata Manufacturing Co

Inventors

• Hayashi Takanori

Classifications

• B62B5/0069 Primary

  Control · CPC title

• B62D51/001

  characterised by the vehicle control device (mechanical features of control devices in general G05G; arrangements of vehicle control devices in general B60K20/00, B60K23/00, B60K26/00) · CPC title

• Y02T10/7275

  Cross-Sectional Technologies · mapped topic

• G05D3/12

  using feedback · CPC title

• B62B3/00

  Hand carts having more than one axis carrying transport wheels; Steering devices therefor; Equipment therefor {(convertible from one-axled to two-axled vehicle B62B1/002)} · CPC title