EP0758554A1 - Exercising apparatus with a crank - Google Patents

Abstract

The training appts. has a DC electric motor, connected in a drive system with crank and pedals (4) operated by user. A four quadrant electronic power unit (5) provides current for the motor (2), which is used for driving and braking the crank in both directions, according to the programme entered in the computer. An incremental transmitter (3) is provided for determining the angular setting, the direction of rotation and speed of the crank. The actual instantaneous values can be freely evaluated, so that these along with further externally measured characteristic values are made available. For the digital regulation (6) and the control (7) of the crank movement, and for the control of or for the further transmission to a peripheral unit.

Description

The invention relates to a movement training device according to the preamble of claim 1.

Known movement training devices of this type available on the market are intended both for healthy people, in particular competitive athletes, and for sick people whose limbs are paralyzed or partially paralyzed. The electric motor used can both brake and drive. In active training, the braking effect is in the foreground, in passive training the driving effect is more important. However, mixed training forms are particularly important in therapeutic treatment when it comes to mobilizing and supporting weak muscle strengths that are still present.

In the known movement training devices, a rotational speed can be preselected or programmed in time, and an upper limit value of the torque can be set, which the electric motor exerts or experiences through the active driving forces of the exercising person. There are, however, constellations in passive and mixed gymnastics, in which at certain angular positions of the crank it would be necessary to intervene in the movement sequence by changing the behavior of the electric motor in order to achieve even better training success and prevent damage.

The invention is therefore based on the object of expanding the area of application of a movement training device of the type described in the introduction and of creating more and more flexible options for the diagnosis and the design of the training process.

• innerhalb einer Kreisbewegung frei programmierbar jedes Bewegungsmuster durchzuführen, und zwar als reine aktive Gymnastik, reine passive Gymnastik oder als Mischung zwischen aktiver und passiver Gymnastik. Bei der Mischgymnastik wird je nach Bedarf unterhalb bestimmter Grenzwerte zwischen Antriebs- und Bremsmoment gewechselt. Die Umschaltung kann augenblicklich erfolgen,
• aus den Kenngrößen der Kurbelbewegung beim passiven Training auf den physischen Zustand des betreffenden Patienten (seine "Leichtgängigkeit) zu schließen,
• während des Trainings die Soll-Kenngrößen in Abhängigkeit von den Ist-Kenngrößen der Kurbelbewegung zu ändern, insbesondere selbsttätig, und
• externe Geräte direkt anzusteuern, z. B. ein Gerät zur funktionellen Muskelstimulation.

This object is achieved by the characterizing features of claim 1. This suggests the use of a freely programmable computer that can access the current actual parameters of the crank movement, in particular also the angular position and the motor current or the torque proportional to it. These parameters are not simply recorded analogously, but are made available as digital variables in a form that can be immediately used. The control and regulation function is also implemented in the computer and can be based on the parameters mentioned. So it is possible

• Freely programmable to perform any movement pattern within a circular movement, namely as pure active gymnastics, pure passive gymnastics or as a mixture between active and passive gymnastics. In mixed gymnastics, a change is made between drive and braking torque below certain limits as required. The switchover can take place immediately,
• to conclude from the parameters of the crank movement during passive training on the physical condition of the patient concerned (his "smoothness),
• during the training to change the target parameters depending on the actual parameters of the crank movement, in particular automatically, and
• to directly control external devices, e.g. B. a device for functional muscle stimulation.

With this movement training device, very special therapeutic needs can be met and training success can be further improved.

An incremental encoder coupled to the crank or its drive is used to record the angular position of the crank. An associated circuit adds the individual pulses and resets the position counter after completion of a cycle by means of a reference signal. If the direction of rotation is opposite, the pulses are subtracted. The circuit also calculates the current speed from the chronological sequence of the pulses. The torque proportional to this is calculated from the motor current. Both parameters are directional values, so that the sign of the speed gives the direction of rotation and the sign of the torque gives the information as to whether it is a driving or a braking torque in relation to the direction of rotation. Apart from their use for regulating and controlling the crank movement, these available actual parameters of the crank movement can be displayed or stored or can also be forwarded for controlling external devices. When stored on an easily transportable medium (memory card, floppy disk), the saved movements can be used externally for therapeutic assessment or as a basis for creating further training programs.

The structure of the control device contained in the computer provides three cascaded controllers, a speed controller and a torque controller being subordinate to an angular position controller. These controllers are processed digitally by the computer and can therefore be flexibly changed even during the runtime of the program. With integrated limiters, upper limit values for the drive torque on the one hand and for the braking torque on the other hand can be set separately.

In addition, an upper limit for the maximum speed can be set during position control.

The computer is preferably implemented as a microcontroller. The control can run a predefined temporal movement program or a movement program that is dependent on the actual parameters of the crank movement or externally determined parameters.

To avoid injury from passive training, it is important that when a spasm occurs, i.e. a muscle spasm, the maximum drive torque is not exceeded. In known movement training devices, reaching a fixed torque limit value leads to the device being switched off, i. H. to completely free-wheel the crank, or to make a countermovement to release the spasm. In a development of the invention, on the other hand, it is proposed that the limit value of the drive torque is automatically tracked to the average drive torque required by the patient so that it is always a certain percentage greater than this. The average drive torque required by the patient is understood to mean practically the upper envelope of the torque curve. This means that the sensitivity to spam detection always remains the same, even if e.g. with improved mobility of the patient in the course of the training, the required average drive torque drops.

Instead of the amount of drive torque, a spasm can also be seen from the rate at which it rises. It rises unusually steeply. Accordingly, it is alternatively proposed to use a limit value of the first derivative of the torque for spasm detection.

The average drive torque required is an important, technically understandable measure of mobility the limbs of a paralyzed patient. Usually the ability to move improves in the course of a training session, so it may be desirable to adjust the speed to the better ability to move. It is therefore proposed that the computer automatically determine the target speed depending on the drive torque.

It has already been mentioned that, for different reasons, it makes sense to store the parameters of the crank movements. Another variant in this respect advantageously consists in that a learning memory is provided for these parameters, which can be activated by an input mode and then stores a movement sequence carried out on the device, which the device can repeat on command. E.g. a therapist can store a specific model movement sequence by executing this movement sequence on the crank, by moving the pedals himself or by the motor using a hand-operated remote control.

Finally, it is proposed that a connection possibility for a muscle stimulation device is provided on the movement training device, the individual stimulation channels, which are connected to the muscle groups in question by electrodes, being controlled as a function of one or more parameters of the crank movement. As a result, the drive movements of the patient supported by stimulation can be approximated to a uniform rotational movement by automatic braking and / or driving the crank.

Spasms can also occur during muscle stimulation. It is therefore proposed that precautions be taken in the computer to immediately interrupt the stimulation pulses in this case and to prevent further ones.

Various parameters must be optimally selected for functional electrical stimulation of the muscles with the intention of achieving the most uniform crank rotation possible. It is about the correct angular position of the crank at which the stimulation pulse is triggered, the length of time of the stimulation or the angle to be traversed, the shape of the stimulation current, which is usually a modulated signal, and the intensity, i.e. the current. It is proposed to provide a special test arrangement with which the stimulation results, which are produced in the form of crank angle rotations, can be measured and compared precisely in dependence on changes in the individual stimulation parameters in order to optimize them automatically. Angular rotation means the whole phenomenon, including the torque that has occurred and registered.

An embodiment of the invention is explained below with reference to the single drawing, which represents a block diagram of a movement training device.

The electromechanical equipment 1 of this device initially comprises a crank which is driven by a permanently magnetically excited direct current machine, in short motor 2. In addition, an incremental encoder 3 is permanently coupled to the motor, which differentiates 2,000 positions on the full angle. With a drive ratio of 20: 1, this results in 40,000 detectable angular positions with one crank revolution. The extremities of a exercising person can attack on the pedals 4 of the crank or other connecting organs.

The motor 2 is fed by four-quadrant power electronics 5. It receives its signals from a controller 6 and a controller 7, which are integrated in a computer 8. The initial values of those in box 1 summarized electromechanical equipment and sensors, ie the motor current and the signals of the incremental encoder 3, reach the controller 6 and controller 7 of the computer via a line 9. From this, the so-called actual parameters of the crank movement, namely the angular position and the speed and torque as directional variables, are obtained. On the other hand, the control 6 and the control 7 are supplied with further characteristic values via lines 10, which were obtained from external sensors. An example of this is the angle values of an angle position sensor attached to a patient's knee. This will be discussed below. The signals to be entered manually are fed to the control via an input 11, e.g. B. a speed setting, on and off impulses, etc. An information output 12 makes it possible to display any parameters, in particular the person exercising, or to store them externally. Finally, an output 13 is provided to peripheral devices such. B. to control a muscle stimulation device.

Some selected functions that can be carried out with the movement training device described are explained below by way of example. This results in further advantages and surprising effects of the invention.

Entry / exit help:

In order to make it easier for paraplegics to insert and secure the legs in the pedals of the movement trainer and, on the other hand, to get out, the pedals are brought into the positions that are favorable for the patient (e.g. left foot in the lower position, then right foot in the lower position) and with them at low speed maximum torque positioned.

Special orthopedic rehabilitation:

After orthopedic operations, it is usually necessary to the knee joint to move passively and actively. To do this, the foot of the leg in question is connected to the pedal of the movement training device.

If it is important to adhere to a certain angular range of the knee movement, e.g. the crank is moved back and forth in a certain angular range that corresponds to the desired angular range of the knee movement. To ensure that the movement of the knee corresponds to the specified range of motion, an angle sensor can be attached to the patient's knee joint and the movement of the knee joint can be carried out in a controlled manner with this information source. The movement can also be carried out with a certain upper limit for the drive or braking torque. If the patient sits too close to the device, the device prompts him to move a little away from the device via an output unit.

If - possibly additionally - an even movement sequence in the knee or hip joint is important, this can be achieved by controlling the crank speed accordingly. As is known, a uniform crank speed results in a non-uniform speed at the joints mentioned. By varying the crank speed as a function of the position within the angular range, however, it can be achieved that the angular speed of either the knee or hip joints remains approximately constant over a large angular range during pedaling.

Resolving a spasm:

Is a spasm z. B. detected by reaching the upper limit of the drive torque, it can be solved with the help of a rocking movement. The rocking movement begins with a small angular deflection, which is increased until the rocking movement changes back into a rotating movement. For example, the therapist can "teach" this or another movement pattern to the movement training device by exercising once, so that it then runs automatically if necessary.

Separate setting of the upper torque limits in drive and braking mode:

The need for such a separate setting is such. B. in the following two training situations.

As far as possible, a patient with very little muscle strength wants to actively push the crank against a noticeable resistance. At the dead center of the crank, he needs the support of the electric motor. This constellation requires that a small braking torque is set in order to create a sense of achievement. On the other hand, a large drive torque is required so that the engine provides strong support at the dead center of the crank.

Another patient is only doing passive training. His skeleton is weak. For safety reasons, it may only be driven with a very small drive torque. However, in order to achieve a round pedaling motion, the motor must brake heavily at certain angular positions of the crank. Provided that there is no gearbox and therefore only a small flywheel mass, rather a belt drive connects the motor and the crank directly, the legs would move from their highest position "fail" below. To avoid this, a relatively large braking torque must be able to be specified.

Warm-up exercise, training suggestion:

A small warm-up phase should be carried out before each training session on the movement training device. The physical condition of the patient ("ease of movement") can be recorded and automatically taken into account via the parameters of the crank movement. The computer can then make a training proposal (speed, duration, etc.), which is calculated from the results of the warm-up training based on experience.

Automatically adjusted limitation of the drive torque:

The maximum drive torque, which is used to detect a spasm, is continuously changed automatically in such a way that it is a certain percentage above the drive torque required for the movement of the patient's extremities. This automatically adjusted drive torque limit value can only rise and fall in the form of a ramp and this has the advantage that the drive torque can never increase suddenly, even when braking hard, for example due to a spasm. So a "soft start" is always guaranteed. Due to the close link between the maximum drive torque and the current drive torque, the responsiveness of the antispastic control remains constant throughout the training.

Automatic adjustment of the speed:

In most patients, the physical condition changes during exercise. Since speed is an important criterion for the extent and effort of an exercise, the setpoint of the speed can be automatically adjusted depending on the "smooth running" of the patient. This tracking takes place depending on the drive torque applied.

Interactive training programs:

The patient can influence the training through his behavior. This has the advantage of reducing the patient's mental and physical passivity during exercise. It can be provided that the speed increases within certain limits the more "smooth" the patient becomes. The speed can be reduced automatically as the active component decreases. A change in direction of rotation can also be provided in the event that the active gymnastics decrease even further.

Activation of an external measuring device:

With a certain constellation of the parameters of the crank movement, which suggests a certain physical situation, an external measuring device is activated in order to take a measurement.

"Teach in" process:

The therapist can teach any movement pattern to a movement training device by selecting a specific input mode and executing the desired movement pattern on the pedals or via the remote control. The device records and saves the executed movement pattern. Then it can reproduce the learned movement pattern.

Functional electrical stimulation depending on the parameters of the crank movement:

A practical case is the electrostimulation of the flexor and extensor muscles on both legs (four stimulation channels), the parameters of the different stimulation channels being selected depending on the actual parameters of the crank movement. A little differentiated control of the muscles usually results in non-uniform, halting movements, while a concentricity of the crank is desired and is pleasantly felt by the patient. The freely programmable control arrangement makes it possible to bring about a continuous pedaling movement by alternately accelerating and braking the movement at the corresponding angular sections. For this purpose, no flywheel is advantageously required, which could lead to injuries if spasms occur.

Automatic optimization of stimulation parameters:

The stimulation therapy is started with an average presetting based on experience. In the subsequent optimization process, the stimulation parameters (e.g. switch-on time and angle, shape of the current curve, intensity) are automatically optimally set using the feedback of the parameters. This can be done sequentially for each muscle group.

Claims (16)

Movement training device with a crank, on the crank arms of which pedals or the like are provided for connection to the feet or arms of a training person, and further comprising an electric motor which is connected to the crank in a geared manner, four-quadrant power electronics for energizing the motor , which makes it possible to use it to drive and brake the crank in both directions of rotation, a device for speed control, a device for torque limitation and a program control device which enables a time-based training program to be specified and run,
characterized,
that a computer (8) is provided which records the angular position and the speed and torque with their respective directions as instantaneous parameters of the crank movement in a digital and thus freely usable form, so that these actual parameters and other externally recorded parameters for digital regulation (6) and control (7) of the crank movement and for controlling or for transfer to peripheral devices are available. Movement training device according to claim 1, characterized in that an incremental encoder (3) coupled to the crank drive is provided for detecting the angular position, the direction of rotation and the speed of rotation of the crank. Movement training device according to claim 1, characterized in that the control device (6) of the computer (8) comprises three cascaded controllers, one of which Angular position controller is a speed controller and a torque controller is subordinate to this. Movement training device according to claim 3, characterized in that upper limit values of the drive torque on the one hand and the braking torque on the other hand can be set separately from one another. Movement training device according to claim 3, characterized in that an upper limit of the speed can be set for the purpose of position control. Movement training device according to claim 1, characterized in that the computer (8) can run a movement program depending on the time or on the available parameters. Movement training device according to claim 6, characterized in that it can execute any desired movement pattern depending on the angular position of the crank. Movement training device according to claim 6, characterized in that upon detection of a spasm, the crank, starting with a counter-movement, is set into a gently reciprocating swiveling movement with increasing angular deflection, which finally changes back into a circular movement in one direction. Movement training device according to claim 1, characterized in that the computer (8) evaluates the digitally available actual parameters of the crank movement in order to draw conclusions about the patient's condition, to indicate this condition by means of significant parameters or to act accordingly on the training process. Movement training device according to claim 9, characterized in that during passive training for the purpose of detecting a spasm, the computer automatically tracks the upper limit value of the drive torque within the framework of a maximum limit value of the upper envelope of the drive torque which is determined from a safety point of view such that the upper limit value is always around a specific one Percentage is greater than the envelope. Movement training device according to claim 9, characterized in that the computer calculates and evaluates the rate of increase of the drive torque during passive training for the purpose of detecting a spasm. Movement training device according to claim 9, characterized in that the computer (8) automatically determines the target speed as a function of the drive torque. Movement training device according to claim 1, characterized in that a learning memory is provided for the parameters of the crank movement, which can be activated by an input mode and then stores a movement sequence carried out on the device, which the device can repeat. Movement training device according to claim 1, characterized in that a connection possibility is provided for a muscle stimulation device, the parameters of the stimulation channels being determined as a function of the actual parameters of the crank movement and wherein the movements of the patient supported by stimulation by automatic braking and / or driving the Crank can be approximated to a uniform rotary movement. Movement training device according to claim 13, characterized in that precautions are taken to Prevent further stimulation impulses. Movement training device according to claim 13, characterized in that an arrangement is provided for the automatic optimization of the stimulation parameters.

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