CONTROLLING A TELEROBOT

Abstract

A method for controlling a telerobot using an input device having a movable control includes detecting an adjustment of the control and an external load acting on the telerobot; determining a target adjustment of a telerobot reference fixed to the robot, based on the detected adjustment of the control; detecting an actual adjustment of the telerobot reference; and controlling drives of the telerobot based on a difference between the actual adjustment and target adjustment. A first operating mode is implemented if the detected load falls in a first range, and a second operating mode is implemented if the detected load falls in a second range. The drives of the telerobot are controlled in the first operating mode such that drive loads of the drives increase with an increase in a one- or multi-dimensional component of the difference in order to reduce the component; and, the drives of the telerobot are controlled in the second operating mode such that drive loads of the drives likewise increase with the same increase in this component of the difference in order to reduce the component, but less than in the first operating mode.

Claims

1. A method for controlling a telerobot (1) by means of an input device which comprises a movable control means (3), comprising the following steps, which in particular are repeated multiple times: detecting (S10) an adjustment of the control means and an external load acting on the telerobot; determining (S20) a target adjustment of a telerobot reference (5) fixed to the robot, based on the detected adjustment of the control means; detecting (S20) an actual adjustment of the reference fixed to the robot; and controlling (S40) drives (1.1-1.6) of the telerobot based on a difference between actual adjustment and target adjustment; wherein a first operating mode is implemented if the detected load is in a first range; and a second operating mode is implemented if the detected load is in a second range; wherein the drives of the telerobot are controlled in the first operating mode in such a way that drive loads of the drives increase with an increase in a one- or multi-dimensional component of the difference between actual adjustment and target adjustment in order to reduce this component; and the drives of the telerobot are controlled in the second operating mode in such a way that drive loads of the drives likewise increase with the same increase in this component of the difference between actual adjustment and target adjustment in order to reduce this component, however they increase less than in the first operating mode.

2-10. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention.

[0062] FIG. 1 schematically depicts a system for controlling a telerobot with an input device according to an embodiment of the present disclosure; and

[0063] FIG. 2 illustrates a method for controlling the telerobot with the input device according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0064] FIGS. 1, 2 show a system or method according to an embodiment of the present invention for controlling a telerobot (arm) 1 using an input device, comprising a base 2.1, a control means 3 movable relative to the base 2.1, and an input device controller 2.2, via a robot controller 4 which communicates wirelessly or by a wired connection with the input device controller 2.2. The input device controller 2.2 can be integrated into the base 2.1.

[0065] In a step S10, an adjustment of the control means 3 is detected, for example the velocity {dot over (x)}.sub.M=v.sub.M thereof is measured by means of and relative to the base 2.1.

[0066] In addition, in step S10, an external force F.sub.ext acting on the telerobot is detected, for example by means of a force-torque sensor 6, or also based on detected loads on joints and/or drives 1.1-1.6 of the telerobot, preferably by means of a mathematical model of the telerobot.

[0067] In a step S20, a target adjustment x.sub.d of a reference 5 fixed to the robot is determined from the detected adjustment {dot over (x)}.sub.M=v.sub.M of the control means 3 by means of a time integration {dot over (x)}.sub.Mdt and a projection f, which in particular can also be an identity. Of course, adjustments of the control means can also be mapped to target adjustments of the reference fixed to the robot, in a manner other than identically, for example scaled, in preferred directions or the like.

[0068] In addition, in step S20, an actual adjustment x of the reference 5 fixed to the robot is detected, for example based on the positions of the joints or drives 1.1-1.6 and a forward kinematics of the telerobot.

[0069] In a step S30, the direction u.sub.fe of the detected external force F.sub.ext acting on the telerobot, preferably in the general form

[00002]$u_{\mathrm{fe}}=\frac{F_{\mathrm{ext}}}{.Math.F_{\mathrm{ext}}.Math.}$ [0070] and a rotation matrix .sup.0R.sub.f, which produces a rotation about an axis u, which is oriented perpendicularly to the unit vector of the z-axis and perpendicularly to the non-permissible direction u.sub.fe,

[00003]$u=\underset{z}{\underset{}{{\left[\begin{array}{ccc}0& 0& 1\end{array}\right]}^T}}\left(-u_{\mathrm{fe}}\right)$ [0071] by the angle

[00004]$={\cos }^{-1}\frac{z.Math.\left(-u_{\mathrm{fe}}\right)}{.Math.z.Math..Math..Math.-u_{\mathrm{fe}}.Math.}$ [0072] are determined and the Cartesian errors {tilde over (x)}=xx.sub.d, {tilde over ({dot over (x)})}={dot over (x)}{dot over (x)}.sub.d are rotated with this rotation matrix into a coordinate system aligned with the external force, preferably in the general form

[00005]${}^f\tilde{x}={}^0{R}_f^T.Math.\tilde{x},{}^f\stackrel{.}{\stackrel{~}{x}}={}^0{R}_f^T.Math.\stackrel{.}{\stackrel{~}{x}}$

[0073] Then, the value of the element k.sub.3,3 of the stiffness matrix

[00006]$K_d=\left[\begin{array}{ccc}{k}_{1,1}& 0& 0\\ 0& k_{2,2}& 0\\ 0& 0& k_{3,3}\end{array}\right]$ [0074] for the time step or sample step n is determined as follows:

[00007]$k_{3,3\left(n\right)}=\{\begin{array}{c}{k}_{\mathrm{high}}.Math.F_{\mathrm{ext}}\left(n\right).Math.<F_{\mathrm{low}}\\ k_{\mathrm{low}}.Math.F_{\mathrm{ext}}\left(n\right).Math.>F_{\mathrm{high}}\\ k_{3,3}\left(n-1\right)F_{\mathrm{low}}.Math.F_{\mathrm{ext}}\left(n\right).Math.F_{\mathrm{high}}\end{array}$ [0075] with the constant, specified values k.sub.high>k.sub.low and F.sub.high>F.sub.low. The specified values of the elements k.sub.1,1, k.sub.2,2 of the stiffness matrix, however, remain constant.

[0076] Then, in a step S40, target drive loads are determined based on a mathematical model of the telerobot, preferably in the general form

[00008]$\left(x\right){\stackrel{.Math.}{x}}_d+\left(x,\stackrel{.}{x}\right).Math.\stackrel{.}{x}+F_g\left(x\right)$ [0077] with the inertia matrix (x) of the telerobot, the vector (x, {dot over (x)}) of the gyroscopic or Coriolis and centrifugal loads and the gravitational loads F.sub.g(x) in the Cartesian workspace, based on a virtual damper between an actual pose change and a target pose change of the reference fixed to the robot, preferably in the general form

[00009]$D_d.Math.{}^f\stackrel{.}{\stackrel{~}{x}}$ [0078] with the damping matrix D.sub.d, and by means of a Cartesian impedance regulation, preferably in the general form

[00010]$x_d=f\left(x_M,v_M={\stackrel{.}{x}}_M\right),{\stackrel{.}{x}}_d=g\left(x_M,v_M={\stackrel{.}{x}}_M\right),\tilde{x}=x-x_d,\stackrel{.}{\stackrel{~}{x}}=\stackrel{.}{x}-{\stackrel{.}{x}}_d$$=J^T\left(q\right).Math.\left(\left(x\right){\stackrel{.Math.}{x}}_d+\left(x,\stackrel{.}{x}\right).Math.\stackrel{.}{x}+F_g\left(x\right)+K_d.Math.{}^f\tilde{x}+D_d.Math.{}^f\stackrel{.}{\stackrel{~}{x}}\right)$ [0079] and the drives are controlled based on these target drive loads, in particular to achieve/exert them, wherein {umlaut over (x)}.sub.d=0 can be selected for simplification.

[0080] It can be seen that, if the external force F.sub.ext acting on the telerobot falls below the lower limit value F.sub.low, a first operating mode is implemented, in which the drives of the telerobot 1 are controlled in such a way that drive loads of the drives increase with an increase in a difference between actual adjustment and target adjustment in order to reduce this difference.

[0081] If the external load F.sub.ext acting on the telerobot exceeds the upper limit value F.sub.high, a second operating mode is implemented, in which the drives of the telerobot 1 are likewise controlled in such a way that drive loads of the drives increase with an increase in a difference between actual adjustment and target adjustment in order to reduce this difference. However, the stiffness of a virtual spring in the component corresponding to the external force F.sub.ext is reduced compared to the first operating mode so that the drive loads of the drives increase less than in the first operating mode with the same increase in this component of the difference between actual adjustment and target adjustment. In the other, complementary component of the difference, however, the stiffness matrix remains constant so that the drive loads of the drives in the first and second operating modes increase equally here. It can also be seen that a hysteresis is provided between the switching between the two values k.sub.high, k.sub.low.

[0082] Although exemplary embodiments have been explained in the preceding description, it is pointed out that a large number of modifications is possible.

[0083] The exemplary embodiment is explained on the basis of an external force and the z-coordinate, without being limited thereto. On the basis of the above explanations, it is clear to a person skilled in the art that, for example, an external torque and/or other implementations, in particular taking into account the component of the difference that corresponds to the external load, are analogously also possible. For example, for an external torque, a direction and corresponding rotation matrix can be determined analogously and a Cartesian error can be transformed therewith.

[0084] It is also pointed out that the exemplary embodiments are merely examples that are not intended to restrict the scope of protection, the applications, and the structure in any way. Rather, the preceding description provides a person skilled in the art with guidelines for implementing at least one exemplary embodiment, with various changes, in particular with regard to the function and arrangement of the described components, being able to be made without departing from the scope of protection as it arises from the claims and from these equivalent combinations of features.

[0085] While the present invention has been illustrated by a description of various embodiments, and while these embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such de-tail. The various features shown and described herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative example shown and described. Accordingly, departures may be made from such details without departing from the spirit and scope of the general inventive concept.

LIST OF REFERENCE SIGNS

[0086] 1 Telerobot [0087] 1.1-1.6 Drive [0088] 2.1 Input device base [0089] 2.2 Input device controller [0090] 3 Control means [0091] 4 Robot controller [0092] 5 Reference fixed to the robot [0093] 6 Force-torque sensor