Pushcart

Patent metadata

Field	Value
Publication number	US-9751551-B2
Application number	US-201615058749-A
Country	US
Kind code	B2
Filing date	Mar 2, 2016
Priority date	Sep 4, 2013
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A pushcart configured to perform inverted pendulum control is made likely to negotiate a step.
In a first control mode, a main body is maintained to have a constant posture by performing the inverted pendulum control all the time. For example, when a user operates a selector switch, the control mode is changed to a second control mode in which offset torque is added so that an amount of torque applied to a wheel driver unit becomes larger. In this case, because the pushcart moves faster than usual, even if there exists a step that is hard to negotiate in the state of usual inverted pendulum control, the pushcart is likely to negotiate that step.

First claim

The invention claimed is:

1. A pushcart comprising:
a wheel;
a driver unit for driving the wheel;
a controller for controlling operations of the driver unit;
a main body configured to support the wheel in a rotatable manner;
a holding portion provided on the main body;
a first sensor unit for detecting an angle change or an angular velocity change in a slope angle of the main body in a pitch direction; and
a step detection input unit configured to receive information of presence/absence of step detection,
wherein the controller has a first control mode in which the operations of the driver unit are controlled so that the angle change in the slope angle of the main body in the pitch direction relative to a target value becomes 0 based on output of the first sensor unit and a second control mode in which torque applied to the driver unit is large in comparison with the first control mode, and
the controller switches between the first control mode and the second control mode based on output of the step detection input unit.

2. The pushcart according to claim 1 ,
wherein the second control mode resets the target value of the slope angle of the main body in the pitch direction toward a forward direction side in a travelling direction of the pushcart.

3. The pushcart according to claim 2 ,
wherein the second control mode adds a predetermine amount of torque in accordance with an amount of change in output of the first sensor unit after having reset the target value of the slope angle of the main body in the pitch direction in addition to torque that the controller applies to the driver unit in the first control mode.

4. The pushcart according to claim 3 , wherein, at a time of transition from the first control mode to the second control mode, the first control mode is stopped for a constant time, the wheel is made to proceed backward in the travelling direction of the pushcart, and thereafter the transition to the second control mode is carried out.

5. The pushcart according to claim 2 ,
wherein, at a time of transition from the first control mode to the second control mode, the first control mode is stopped for a constant time, the wheel is made to proceed backward in the travelling direction of the pushcart, and thereafter the transition to the second control mode is carried out.

6. The pushcart according to claim 2 ,
wherein the step detection input unit includes a switch provided in the holding portion.

7. The pushcart according to claim 1 ,
wherein the second control mode adds a predetermined amount of torque in accordance with an amount of change in output of the first sensor unit in addition to the torque that the controller applies to the driver unit in the first control mode.

8. The pushcart according to claim 7 ,
wherein, at a time of transition from the first control mode to the second control mode, the first control mode is stopped for a constant time, the wheel is made to proceed backward in the travelling direction of the pushcart, and thereafter the transition to the second control mode is carried out.

9. The pushcart according to claim 1 ,
wherein, at a time of transition from the first control mode to the second control mode, the first control mode is stopped for a constant time, the wheel is made to proceed backward in the travelling direction of the pushcart, and thereafter the transition to the second control mode is carried out.

10. The pushcart according to claim 1 ,
wherein the step detection input unit includes a switch provided in the holding portion.

11. The pushcart according to claim 1 ,
wherein the step detection input unit includes a potentiometer, an encoder, or a plurality of switches provided in the holding portion.

12. The pushcart according to claim 11 ,
wherein the potentiometer, the encoder, or the plurality of switches, after having received step detection input, return to an initial state.

13. The pushcart according to claim 11 ,
wherein the second sensor unit includes a wheel stop detection unit for detecting the wheel being stopped.

14. The pushcart according to claim 13 ,
wherein the wheel stop detection unit is a rotary encoder configured to detect a number of rotations of the wheel and detects the wheel being stopped in accordance with an output value of the rotary encoder.

15. The pushcart according to claim 12 ,
wherein the second sensor unit includes a shock sensor.

16. The pushcart according to claim 12 ,
wherein the second sensor unit includes a distance measurement sensor, and
the controller determines, based on a distance to a step detected by the distance measurement sensor, whether or not the step is negotiable.

17. The pushcart according to claim 16 ,
wherein, in the case where the distance to the step detected by the distance measurement sensor falls within a predetermined range, the controller switches from the first control mode to the second control mode.

18. The pushcart according to claim 1 ,
wherein the step detection input unit includes a second sensor unit for detecting a step.

19. The pushcart according to claim 18 ,
wherein the second sensor unit is a step height detection sensor for detecting a height of a step, and when the step height detection sensor detects a step having a height that is equal to or higher than a predetermined threshold, the controller determines that there exists a step and switches from the first control mode to the second control mode.

20. The pushcart according to claim 19 ,
wherein, in the case where it is determined that there exists a step, the controller determines whether or not the step is negotiable based on height information of the step detected by the step height detection sensor, and switches from the first control mode to the second control mode only when the step is determined to be negotiable.

Assignees

• Murata Manufacturing Co

Inventors

• Shirato Kenichi

Classifications

• A61H2201/5069

  Angle sensors · CPC title

• A61H2201/5028

  Contact activation, i.e. activated at contact with a surface of the user to be treated · CPC title

• A61H2201/5092

  Optical sensor · CPC title

• A61H3/04

  Wheeled walking aids for patients or disabled persons · CPC title

• B62B5/0033

  Electric motors · CPC title