Power assist vehicle

• US 6,807,465 B2
• Filed: 09/24/2002
• Issued: 10/19/2004
• Est. Priority Date: 08/31/1999
• Status: Expired due to Fees

• Current Assignee: Dana R. Yoerger, Nathan Ulrich
• Original Assignee: Dana R. Yoerger, Nathan Ulrich
• Inventors: Ulrich, Nathan, Yoerger, Dana R.
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US10/253,281
• Publication Number:
  US 20030018417A1
• Time in Patent Office: 756 Days
• Field of Search: 701/1, 701/51, 701/56, 701/41, 180/907, 180/65.1, 180/6.5, 280/250.1
• US Class Current: 701/1
• CPC Class Codes: A61G 2203/38 for torque
• CPC Class Codes: A61G 5/045 Rear wheel drive
• CPC Class Codes: A61G 5/048 Power-assistance activated by pushing on hand rim or on handlebar
• CPC Class Codes: A61G 5/1054 Large wheels, e.g. higher than the seat portion
• CPC Class Codes: B60K 17/043 Transmission unit disposed in on near the vehicle wheel, or between the differential gear unit and the wheel
• CPC Class Codes: B60K 2007/0046 the motor moving together with the vehicle body, i.e. moving independently from the wheel axle
• CPC Class Codes: B60K 2007/0061 the motor axle being parallel to the wheel axle
• CPC Class Codes: B60K 7/0007 the motor being electric
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2200/34 Wheel chairs
• CPC Class Codes: B60L 2220/14 Synchronous machines
• CPC Class Codes: B60L 2220/16 DC brushless machines
• CPC Class Codes: B60L 2220/44 Wheel Hub motors, i.e. integrated in the wheel hub
• CPC Class Codes: B60L 2220/46 Wheel motors, i.e. motor connected to only one wheel
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2240/463 Torque
• CPC Class Codes: B60L 2250/12 : by confirmation, e.g. of the input
• CPC Class Codes: B60L 50/51 : characterised by AC-motors
• CPC Class Codes: B60Y 2200/84 : Wheelchairs
• CPC Class Codes: B62D 51/04 : the driver walking
• CPC Class Codes: F16H 1/20 : involving more than two intermeshing members
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y10S 180/907 : Motorized wheelchairs

Abstract

A power-assist vehicle such as a wheelchair senses driving torque/force applied by a user through a transmission. The detected force/torque is utilized in a control system with a control map defining a desired dynamic of the vehicle and programmed with the desired mass and drag parameter.

Claims

1. A wheelchair comprising:

first and second drive wheels each having an axis and a coaxial handrim for receiving a driving torque from a user;

each drive wheel being coupled to a motor; and

a control system programmed with at least one control map defining a desired dynamic of the wheelchair and programmed with a desired mass parameter and a desired drag parameter, the control system utilizing said control map and measured values of said driving torque from said user and an actual velocity to determine a desired velocity and control the motor to reduce an error component between said actual velocity and said desired velocity.

2. The wheelchair of claim 1 wherein said drag parameter comprises a coulomb damping parameter.

3. The wheelchair of claim 1 wherein said drag parameter further includes a linear damping parameter.

4. The wheelchair of claim 1 wherein said desired velocity is produced in response to an iterative integration of:

measured handrim torque multiplied by a first constant;

the negative of the desired velocity multiplied by a second constant; and

the negative of the sign of the desired velocity multiplied by a third constant.

5. A power assist vehicle comprising:

a drive wheel;

input means for receiving a driving torque from a user;

a motor; and

a control system programmed with at least one control map defining a desired dynamic of the vehicle and programmed with a desired mass parameter and a desired drag parameter, the control system utilizing said control map and measured values of said driving torque from said user and an actual velocity to determine a desired velocity and employs a single-axis velocity servo loop to control the motor to reduce an error compound between said actual velocity and said desired velocity.

6. The wheelchair of claim 5 wherein said desired velocity is produced in response to an iterative integration of:

measured user-applied torque multiplied by a first constant; and

the negative of the sign of the desired velocity multiplied by a second constant.

7. The wheelchair of claim 5 wherein said desired velocity is produced in response to an iterative integration of:

measured user-applied torque multiplied by a fist constant; and

a damping effect provided by a function of the desired velocity.