Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Reexamination Certificate
1999-10-04
2001-03-20
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
C318S568210, C318S646000, C254S001000, C901S050000
Reexamination Certificate
active
06204619
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to power-assist devices. More particularly, the present invention relates to a method and system for dynamically controlling a power-assisted lift system to continuously reduce operator strain in a real-time mode.
2. Discussion of the Related Art
In the automotive industry, lift devices are often employed in car assembly line stations to assist human operators with difficult tasks. These devices are most useful in stations requiring the lifting and manipulation of heavy loads. A typical device is primarily designed to balance the gravity of a load during lifting and travel around an assembly line station. The human operator, however, must still push or pull the device in order to move it horizontally for parts assembling. These actions require the operator to either accelerate or decelerate the load-carrying device each time a change in direction is desired. This directional change is particularly difficult when each major link of the device is large in mass and has significant moments of inertia which add to the amount of work to be done. To further aggravate the problem, a typical operation in a car assembly line will often be repeated in excess of 50 times per shift. This repetition has the potential to cause cumulative wrist or arm injury after consecutive months of work. Power-assisted lift devices were therefore developed to address the major concerns of ergonomics and human factors engineering.
Typical power-assisted approaches provide lift devices with four-axis motion. These devices are driven by servo-motors and guided by a closed-loop feedback of force data. In one system manufactured by FANUC Robotics, Inc., the force data are monitored and measured by a six-axis force sensor mounted behind the manual handle of the device. The current status of the feedback loop, however, is based only on the kinematics/statics relation between Cartesian positions/forces and joint positions/torques of the device. Thus, these systems have a noticeably slow response to operator-induced changes in direction. The slow response results in significant strain on operators any time a change in direction is attempted. It is therefore desirable to use joint data to provide a dynamic compensation within a substantially shorter response time.
SUMMARY OF THE INVENTION
The present invention provides a power-assisted lift system for assisting a human operator in manipulating objects. The lift system has a power-assist device that generates and measures joint data. The lift system also has a sensing module for converting a human-applied force into force data. The lift system further includes a dynamic control system for continuously reducing operator strain in a real-time mode based on the force data and the joint data.
The present invention also provides a dynamic control system for continuously reducing strain on a human operator of the power-assisted lift system, wherein the lift system has a plurality of joints. The control system has a statics formulator for determining a set of static torques for the lift system based on force data and joint data of the power-assist device. The control system further includes a dynamics formulator for determining a dynamic torque required for each joint of the power-assist device based on the joint data and static torques. The control system also includes a torque summation module for summing the dynamic torques with the static torques to determine torque data for each joint of the power-assist device. The torque summation module applies the torque data to the power-assist device to dynamically compensate human operation.
As an additional feature, the invention includes a computer implemented method for controlling a power-assist device. The method includes the step of retrieving force data from the power-assist device. The force data results from human operation of the power-assist device. The method further includes the step of retrieving joint data from the power-assist device. The method then compensates the human operation of the power-assist device based on the force data and the joint data.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.
REFERENCES:
patent: 3628505 (1971-12-01), Myers
patent: 3904042 (1975-09-01), Colston
patent: 3940110 (1976-02-01), Motoda
patent: 5739811 (1998-04-01), Rosenberg et al.
patent: 5742138 (1998-04-01), Kato et al.
patent: 5865426 (1999-02-01), Kazerooni
patent: 5915673 (1999-06-01), Kazerooni
patent: 6084371 (2000-07-01), Kress et al.
Gu Edward Y. L.
Oriet Leo Paul Gerard
DaimlerChrysler Corporation
Fuller III Roland A.
Ro Bentsu
LandOfFree
Dynamic control algorithm and program for power-assisted... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dynamic control algorithm and program for power-assisted..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dynamic control algorithm and program for power-assisted... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2462200