# US 9,751,551 B2 · Pushcart > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,751,551 B2 - Document ID: US9751551B2 - Status: Granted - Kind: B2 - Application number: 15/058,749 - Filed: 2016-03-02 - Published: 2016-06-23 - Granted: 2017-09-05 - Earliest claimed: 2013-09-04 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Kenichi Shirato - Web page: https://patentgrep.com/patent/US9751551B2 ## CPC - B62B 5/0069: {Control} - A61H 3/04: Wheeled walking aids for patients or disabled persons - B62B 1/00: Hand carts having only one axis carrying one or more transport wheels; Equipment therefor - B62B 5/0033: {Electric motors} - B62B 5/02: providing for travelling up or down a flight of stairs (chairs or multi-track cycles specially adapted for invalids A61G5/00) - A61H 2003/043: {with a drive mechanism} - A61H 2003/046: {with braking means} - A61H 2201/5007: computer controlled - A61H 2201/5028: Contact activation, i.e. activated at contact with a surface of the user to be treated - A61H 2201/5069: Angle sensors - A61H 2201/5084: Acceleration sensors - A61H 2201/5092: Optical sensor - B62B 1/10: in which the load is intended to be transferred totally to the wheels - B62B: HAND-PROPELLED VEHICLES, e.g. HAND CARTS OR PERAMBULATORS; SLEDGES (characterised by animal propulsion B62C; propulsion of sledges by driver or engine B62M) - A61H: PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY (electrotherapy, magnetotherapy, radiation therapy or ultrasound therapy A61N) ## 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. ## Claims ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 2) 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. ### Claim 4 (depends on 3) 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. ### Claim 5 (depends on 2) 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. ### Claim 6 (depends on 2) The pushcart according to claim 2, wherein the step detection input unit includes a switch provided in the holding portion. ### Claim 7 (depends on 1) 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. ### Claim 8 (depends on 7) 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. ### Claim 9 (depends on 1) 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. ### Claim 10 (depends on 1) The pushcart according to claim 1, wherein the step detection input unit includes a switch provided in the holding portion. ### Claim 11 (depends on 1) 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. ### Claim 12 (depends on 11) 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. ### Claim 13 (depends on 11) The pushcart according to claim 11, wherein the second sensor unit includes a wheel stop detection unit for detecting the wheel being stopped. ### Claim 14 (depends on 13) 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. ### Claim 15 (depends on 12) The pushcart according to claim 12, wherein the second sensor unit includes a shock sensor. ### Claim 16 (depends on 12) 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. ### Claim 17 (depends on 16) 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. ### Claim 18 (depends on 1) The pushcart according to claim 1, wherein the step detection input unit includes a second sensor unit for detecting a step. ### Claim 19 (depends on 18) 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. ### Claim 20 (depends on 19) 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.