Various balancing robots or devices have been developed. Such devices rely on some type of active balancing mechanism that operates to effectively balance a device within an active balancing range. However, it is possible under some circumstances for the device to be outside the balancing range, for example when the device has somehow fallen over or when it is first activated. It would be useful if techniques could be developed to balance a device that is outside of the balancing range.
The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, and in which:
The invention can be implemented in numerous ways, including as a process, an apparatus, a system, a composition of matter, a computer readable medium such as a computer readable storage medium or a computer network wherein program instructions are sent over optical or electronic communication links. In this specification, these implementations, or any other form that the invention may take, may be referred to as techniques. A component such as a processor or a memory described as being configured to perform a task includes both a general component that is temporarily configured to perform the task at a given time or a specific component that is manufactured to perform the task. In general, the order of the steps of disclosed processes may be altered within the scope of the invention.
A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate the principles of the invention. The invention is described in connection with such embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.
In various embodiments described herein, a balancing device is either in an actively balanced state or in an unbalanced state. The device includes an active balancing mechanism (ACBM), an auxiliary balancing mechanism (AUBM), and a processor that controls a transition between the actively balanced state and the unbalanced state. The device is in the actively balanced state when it is inside a range of the active balancing mechanism. The auxiliary balancing mechanism is deployed to aid the transition between the actively balanced state and the unbalanced state, and is stowed after the transition is complete. The device includes a processor for controlling the active balancing mechanism and the auxiliary balancing mechanism in such a manner as to achieve a successful and smooth transition between the two states. In one embodiment, the balancing device is a robot, while the active balancing system comprises a pair of lateral wheels driven by a motor and the auxiliary balancing system comprises a lifting arm. In another embodiment, the device is a toy doll, while the active balancing system comprises a pair of weighted arms and the auxiliary balancing system comprises a spring.
Measuring unit 103 measures the position of the auxiliary balancing mechanism, which is either being deployed or being stowed during a balancing state transition. In this embodiment, the auxiliary balancing mechanism comprises a lifting arm driven by a lift motor. The measured position of the lifting arm is used by processor 100 for determining the torque the lift motor needs to apply to the lifting arm during transition, and sends it to a lift motor driver 102.
During the AUBM deployment at position 308, a torque 316 is applied to the lifting arm 313 by a lift motor to achieve constant deploying velocity. Torque 316 is determined by a closed loop control mechanism with a processor as described in
AUBM Torque=(Vp·Kp)+(Vd·Kd)+(∫Vp·Ki)
wherein Vp is the difference between the instant AUBM deploying velocity and the desired AUBM deploying velocity; Vd is the derivative of Vp; ∫Vp is the integral of Vp; Kp, Kd and Ki PID constants.
In this embodiment, the control mechanism is implemented in discreet constant time intervals. Vd is determined by the difference between the current Vp and the Vp measured at the previous time step:
Vd(t)=Vp(t)−Vp(t−1)
During the AUBM deployment, the ACBM keeps the device actively balanced. Due to the change of the device's weight distribution, the equilibrium angle has to be adjusted by an offset ΔΘ 317 to maintain zero wheel velocity. ΔΘ 317 is determined by a closed loop control mechanism with a processor as described in
ΔΘ=(WVp·WKp)+(WVd·WKd)+(∫WVp·WKi)
wherein WVp is the instant wheel velocity; WVd is the derivative of WVp; ∫WVp is the integral of WVp; WKp, WKd and WKi are PID constants.
In this case, there are two control mechanisms working together to keep the device actively balanced with zero wheel velocity. The closed loop described by the equation above determines the equilibrium angle offset ΔΘ 317 and feeds it to the ACBM. The ACBM in turn calculates the new equilibrium angle to balance the device.
At position 309, after the AUBM is fully deployed, a torque 318 is applied by the main motor to the pair of wheels 314 for providing a kick to unbalance the device and make it tip over towards the deployed AUBM. Torque 318 is proportional to an angle 319 between the two device body positions at 309 and 310. In this embodiment, torque 318 is applied for a constant time period. Torque 318 is determined by the following equation:
Torque=ΔΘ·T·Kp+T·Kc
wherein ΔΘ is the deviation from the actively balanced state, or the angle between the two device body positions in this embodiment, T is a constant time period, Kp and Kc are two constants.
The kick is big enough to tip over the device body, which will then be caught by the deployed AUBM, or lifting arm 313 at position 310. The device then proceeds towards a final resting position 312 through an intermediate position 311 as described in
Torque=−(ΔΘ·T·Kp+T·Kc)
wherein ΔΘ is the deviation from the actively balanced state, or angle 415, the difference between the initial equilibrium angle and the device body angle at position 409 in this embodiment, T is a constant time period, Kp and Kc are two constants.
During the AUBM stowage at position 411, a torque 416 is applied to the lifting arm by a lift motor to achieve constant stowage velocity. Torque 416 is determined in the same manner as torque 316 is and follows the same equation likewise:
Torque=(Vp·Kp+(Vd·Kd)+(∫Vp·Ki)
During the AUBM stowage at position 411, the ACBM keeps the device actively balanced and the equilibrium angle is adjusted by an offset ΔΘ 417 to achieve zero wheel velocity. ΔΘ 417 is determined by the following equation:
ΔΘ=(WVp·WKp)+(WVd·WKd)+(∫WVp·WKi)
A system and method for controlling the transition between an actively balanced state and an unbalanced state has been described. Various embodiments include an active balancing mechanism, an auxiliary balancing mechanism, and a processor for closed loop controls. In one embodiment, the active balancing mechanism comprises a pair of lateral wheels and the auxiliary balancing mechanism comprises a lifting arm. In other embodiments, the active balancing mechanism comprises a weighted arm and the auxiliary balancing mechanism may comprise a spring. Various closed loop control mechanisms implemented with a processor for controlling the transition have been described. In one embodiment proportional, derivative and integral control is used for the control mechanisms.
Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, the invention is not limited to the details provided. There are many alternative ways of implementing the invention. The disclosed embodiments are illustrative and not restrictive.
This application is a continuation of U.S. patent application Ser. No. 12/322,667 entitled BALANCING DEVICE filed Feb. 4, 2009, which is a continuation of U.S. patent application Ser. No. 11/429,644 now U.S. Pat. No. 7,506,545 entitled BALANCING DEVICE filed May 5, 2006, which claims priority to U.S. Provisional Application No. 60/678,456 entitled BALANCING ROBOT filed May 5, 2005 which are incorporated herein by reference for all purposes.
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Number | Date | Country | |
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20110270538 A1 | Nov 2011 | US |
Number | Date | Country | |
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60678456 | May 2005 | US |
Number | Date | Country | |
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Parent | 12322667 | Feb 2009 | US |
Child | 13180383 | US | |
Parent | 11429644 | May 2006 | US |
Child | 12322667 | US |