DE102019219920A1 - STEERING CONTROL OF A PERSONAL TRANSPORT DEVICE - Google Patents

Abstract

Control unit for a passenger transport device, comprising a balance control unit and a steering control unit, the control unit being configured to switch to at least the following operating states: an idle state 10 in which both the balance control unit and the steering control unit are deactivated; a balance state 20 in which the balance control unit is activated and the steering control unit is deactivated; and an active state 30 in which both the balance control unit and the steering control unit are activated.

Description

The present invention relates to a control unit of a person transport device, a method for controlling a person transport device and a person transport device with such a control unit.

A self-balancing passenger transport device such as a Segway or an e-board (also known as a hoverboard) is an electrically driven means of transport with usually two wheels mounted on the same axis, between which at least one step surface extends essentially along the axis, which a user can use as a standing surface during the use of the passenger transport device is used.

Such a person transport device maintains itself in balance by means of an electronic drive control, with a locomotion of the transport device normally being controlled by shifting the weight of the user. The electronic drive control automatically moves the transport device in the direction in which the user leans.

When cornering, the steering of such a passenger transport device can either be controlled by an operating unit, usually by a handlebar in the middle of the passenger transport device, or also by the weight shift of the user. In order to compensate for the centrifugal force when cornering, the user automatically leans towards the center of the corner when initiating cornering. This can also be observed when cycling, for example. Based on this, methods have therefore been developed in the prior art to detect these movements and to derive steering commands from them.

However, the solutions in the prior art have the disadvantages that getting on or off can also erroneously be interpreted as a steering command, which leads to undesired rotations of the passenger transport device and thus makes getting on or off difficult or even impossible.

Another problem for the steering control of such a transport device is the competition between the balance control and the steering control for the available torque of a motor.

Self-balancing vehicles drive with a "dynamic stabilization". They are actively driven by an electric motor or the like to take an upright position and not tip over. When the user leans forwards or backwards, this movement or the angle of inclination of the vehicle is detected by sensors and accordingly the vehicle moves forwards or backwards in order to maintain balance.

Steering of such a self-balancing passenger transport device is preferably implemented by means of a speed difference between the wheels. That is, when a user wants to start cornering, one wheel will turn faster than the other to create a speed difference. To do this, the torque of the motor for one wheel is increased for acceleration and at the same time the torque of the motor for the other wheel is reduced to enable the steering.

This means that the balance control and the steering control both “compete” for the available torque of the motors. If a user wants to make a steering movement while accelerating strongly, there is a risk that the equilibrium of the vehicle can no longer be maintained due to the limited torque of the motors that is still available, so that the vehicle tips over and the user is injured .

In order to increase the stability of a self-balancing passenger transport device, solutions have been developed in the prior art which, for example, monitor the speed of such a passenger transport device and prevent the user from driving too fast and reaching the limit of stability. However, the influence of the steering on the stability is not taken into account in such solutions. In addition, the influence of the torque limit of the individual motors on the stability of the passenger transport device is not examined. When a user accelerates very quickly, the engine is loaded with a large torque. If the user wants to steer at the same time, the engine is loaded even more and the stability is endangered. Such a problem cannot be solved with the prior art.

It is therefore the object of the present invention, according to the following aspects, to offer an improved steering control solution for a self-balancing passenger transport device which addresses one or more of the above-mentioned disadvantages or problems of the prior art.

According to a first aspect of the invention, the object is achieved by a control unit for a person transport device, preferably for a self-balancing person transport device, comprising a Balance control unit and a steering control unit, the control unit being set up to switch to at least the following operating states: a) an idle state in which both the balance control unit and the steering control unit are deactivated, b) a balancing state in which the balance control unit is activated and the Steering control unit is deactivated, and c) an active state in which both the balance control unit and the steering control unit are activated.

A state of rest is a state with a deactivated drive train, whereby the state of rest can be present, for example, when the user's feet are not on the step surface.

A balance state is a state with an activated balance control and a deactivated steering control, whereby the balance state can exist, for example, when the user steps on the step surface or steps off the step surface and only one of his feet is on the step surface.

An active state is a state in which both the balance control unit and the steering control unit are activated, wherein the active state can exist, for example, when the user has stepped onto the step surface and both of his feet are on the step surface.

Switching between the above-mentioned states has the advantage that the balance control or the steering control is activated or deactivated depending on the state, so that undesired movements of the passenger transport device, such as, for example, rotational movements when climbing or dismounting, can be avoided.

In a preferred embodiment, the control unit is set up to switch from one operating state to another operating state when at least one transition condition from one operating state to the other operating state is met. That is, the switching between the states is preferably triggered by the fulfillment of one or more transition conditions. Thus, the states as well as the switching between the states can be represented together as a state machine.

The passenger transport device preferably has at least one step surface that serves as a standing surface for a user while using the passenger transport device, wherein the control unit is preferably set up to detect a foot movement of the user, and where the at least one transition condition is met by at least one detected foot movement of the User is enabled.

Switching between two states is thus preferably triggered by a foot movement of a user or a step of a foot movement. The movement can be climbing up or down, stepping up again consisting of at least two steps, the first step being placing a first foot of the user on the tread and the second step being followed by pulling the second foot of the user and thus can be a completion of the ascension movement. Similarly, dismounting also consists of at least two steps, wherein the first step can be lifting a first foot of the user off the tread and the second step can be dragging the second foot of the user and thus completing the descent movement.

A state transition from a state of rest to a state of balancing can thus take place in that the user places one of his feet on the step surface of the passenger transport device when climbing up.

A state transition from a balanced state to an active state can take place in that the user places his second foot on the step surface of the passenger transport device when climbing after his first foot has already been placed on the step surface.

A state transition from an active state to a balancing state can take place in that, when dismounting, a foot of the user is lifted and leaves the step surface.

A state transition from a balanced state to a state of rest can take place in that the user puts the second foot off the step surface of the passenger transport device when stepping down after his first foot has already been put down from the step surface.

In a preferred embodiment, the control unit is set up to detect the at least one foot movement by means of one or more force sensors. A force sensor can be implemented with different solutions, for example it can be a load cell that functions similarly to a scale, where the force exerted on the load cell deforms a bending beam of the load cell, for example, and this deformation is measured via a strain gauge. The force sensor can also be a force sensing resistor (FSR sensor), the resistance of the FSR sensor changing depending on the force that acts on it.

It should be noted, however, that the detection of foot movement is not restricted to a force sensor. Other sensors can also be used to detect foot movement, which sensors can include, for example, one or more of the following sensors: optical sensors that measure physical deflection; Sensors that measure the hydraulic pressure in chambers in the vehicle; capacitive sensors; path-dependent sensors; or a combination of the above sensor types.

The control unit is preferably set up to determine the at least one transition condition based on one or more of the following parameters: the total weight of the user on the step surface, at least one contact force of the user on the step surface, at least one time derivative of the total weight of the user on the step surface , at least one time derivative of a contact foot force of the user on the step surface, at least one factor determined from several contact foot forces of the user on the step surface, at least one speed of the passenger transport device.

For the determination of the transition condition or for the detection of a foot movement, not only the total weight of the user on the step surface or one or more contact foot forces of the user on the step surface but also their temporal derivatives are important, because the contact foot forces of the user e.g. when climbing and change time of descent. In addition, a factor which is determined from several distributed contact foot forces of the user in different areas of the tread surface can be used to determine or record a foot movement. The speed of the passenger transport device should preferably also be taken into account.

The at least one transition condition is preferably defined by comparing the one or more parameters with a predetermined threshold value in each case.

When determining the threshold value of at least one transition condition, one or more of the following additional parameters should preferably also be taken into account: at least one measured or estimated unevenness of the ground, at least one acceleration of the passenger transport device, at least one yaw rate of the passenger transport device, the weight of the user. These parameters can also play an important role in determining a transition condition. For example, the measurement of the driver's weight can be influenced by driving over uneven floors such as door sills, lowered curbs and cobblestones, with the measured weight being less than the actual weight of the driver. For this reason, such unevenness in the ground should preferably be taken into account when determining the transition conditions. In addition, the actual weight of the user can also play an important role, wherein the one or more transition conditions can vary depending on the weight of the driver.

According to a second aspect of the present invention, the object is achieved by a method for controlling a passenger transport device which comprises a balance control unit and a steering control unit, the method comprising switching into at least the following operating states: a) an idle state in which both the balance control unit and the steering control unit are also deactivated, b) a balance state in which the balance control unit is activated and the steering control unit is deactivated, and c) an active state in which both the balance control unit and the steering control unit are activated.

Further preferred embodiments of the method according to the second aspect of the invention are claimed in claims 9-14.

According to a third aspect of the present invention, the object is achieved by a people transport device, comprising at least one step surface, which serves as a standing surface for a user when using the people transport device, and a control unit according to one of claims 1-7.

According to a fourth aspect of the present invention, the object is achieved by a control unit for a self-balancing passenger transport device, which has two or more ground contact units each driven by a motor, the control unit comprising a balance control unit for balance control and a steering control unit for steering control, wherein the control unit is set up, if a torque of the motor of a ground contact unit, which is required for a desired steering and a simultaneous balance control, exceeds the maximum torque of the motor, to prioritize the balance control via the steering control.

A prioritization of the balance control via the steering control can improve the stability of a self-balancing passenger transport device and thus prevent the passenger transport device from tipping over, above all if the user accelerates too quickly and gives a steering command at the same time.

In order to determine the available torque of a motor of a ground contact unit, the maximum torque of the motor, namely the torque limit of the motor, should preferably first be determined. In a preferred embodiment, the control unit is therefore set up to determine the maximum torque of the motor of a ground contact unit M _Max , the control unit preferably being set up to determine _{the maximum torque of the motor M Max} at least on the basis of one or more of the following parameters: a winding temperature of the motor, a state of charge of at least one battery of the motor, the capacity of the at least one battery of the motor, a speed of the motor, an internal temperature of a servo amplifier of the motor.

Furthermore, according to the fourth aspect of the invention, the control unit is preferably set up to determine a _{torque M equilibrium required for the equilibrium control of the passenger transport device.}

The available torque of the engine can be determined on the basis of the determined M _Max and M _Equilibrium. In a further preferred embodiment, the control unit is set up to determine a torque of the motor M _{steering reserve of} a ground contact unit that is available for a steering, wherein: $${\mathrm{M.}}_{\mathrm{L.}enkunGsreserve}\le {\mathrm{M.}}_{\mathrm{M.}ax}-{\mathrm{M.}}_{GleicHGewicHt}.$$

• - wenn M_{Gleichgewicht} + M_{Lenkungsbefehl} ≤ M_Max , die Steuerungseinheit dafür eingerichtet ist, das Drehmoment des Motors einer Bodenkontakteinheit auf einer Seite der Transportvorrichtung um M_{Lenkungsbefehl} zu erhöhen, und das Drehmoment des Motors einer Bodenkontakteinheit auf der anderen Seite der Transportvorrichtung um M_{Lenkungsbefehl} zu reduzieren.
• - wenn M_{Gleichgewicht} + M_{Lenkungsbefehl} > M_Max, die Steuerungseinheit dafür eingerichtet ist, das Drehmoment des Motors einer Bodenkontakteinheit auf einer Seite der Transportvorrichtung um ein anderes Drehmoment M_{Lenkungssteuerung} zu erhöhen, und das Drehmoment des Motors einer Bodenkontakteinheit auf der anderen Seite der Transportvorrichtung um das andere Drehmoment M_{Lenkungssteuerung} zu reduzieren, wobei

$${\text{M}}_{\text{Gleichgewicht}}+{\text{M}}_{\text{Lenkungssteuerung}}\le {\text{M}}_{\text{Max}}.$$

In a further preferred embodiment, the control unit is set up _{to determine a torque M steering} command required for a desired steering according to a steering command, wherein:

• - if M _balance + M _steering command ≤ M _Max , the control unit is set up to increase the torque of the motor of a ground contact unit on one side of the transport device by M _steering command, and the torque of the motor of a ground contact unit on the other side of the transport device by M _{steering command} to reduce.
• - if M _balance + M _steering command> M _Max , the control unit is set up to increase the torque of the motor of a ground contact unit on one side of the transport device by a different torque M _{steering control} , and the torque of the motor of a ground contact unit on the other side of the transport device to reduce the other torque M _{steering control} , where

$${\text{M.}}_{\text{balance}}+{\text{M.}}_{\text{Steering control}}\le {\text{M.}}_{\text{Max}}.$$

As mentioned in the introduction, a self-balancing passenger transport device is steered by a speed difference between the ground contact units. To enable cornering, a ground contact unit on one side rotates faster than another ground contact unit on the other side. For this purpose, the torque of the motor for the one ground contact unit is increased for acceleration and at the same time the torque of the motor for the other ground contact unit is reduced.

In order to maintain the balance, however, the torque of the motor for one ground contact unit and the torque of the motor for the other ground contact unit must be increased or reduced by the same amount, so that the average torque of the motors remains unchanged and thus the balance of the passenger transport device is not disturbed.

However, if the M _{steering command is} greater than the M _{steering reserve of} a motor, it is no longer possible to increase the torque of the motor by M _{steering command.} In this case, if the torque of the other motor is _{reduced by M steering} command anyway, the average torque of the motors changes. Thus, the equilibrium of the passenger transport device can no longer be maintained. Therefore, according to the invention, the balance control should be prioritized over the steering control in this situation. In particular, the torque of the respective motors is _{increased or decreased by a torque M steering control} which is different from the torque M _steering command, where M _{steering control is} equal to M _steering reserve or less than M _steering reserve.

According to a fifth aspect of the present invention, the object is achieved by a method for controlling a self-balancing passenger transport device which has two or more ground contact units each driven by a motor, the passenger transport device furthermore having a balance control unit for balance control and a steering control unit for steering control wherein the method comprises, if a torque of the motor of a ground contact unit required for a desired steering and a simultaneous balance control, the maximum torque of the motor exceeds the equilibrium control prioritized over the steering control.

Further preferred embodiments of the method according to the fifth aspect of the invention are claimed in claims 23-27.

According to a sixth aspect of the present invention, the object is achieved by a people transport device comprising two or more ground contact units, each driven by a motor, and a control unit according to one of claims 16-21.

According to a seventh aspect of the present invention, the object is achieved by a steering control unit for steering a passenger transport device, which has at least one step surface that serves as a standing surface for a user when using the passenger transport device, wherein the steering control unit is set up based on a steering factor φ, which is calculated from at least four measured or determined contact foot forces for the front and rear foot regions of the user on the at least one step to control the steering of the passenger transport device, the at least four contact foot forces being: contact foot force front left F _VL , contact foot force front right F _VR , Rear left _{foot force} F HL, right rear foot force F _HR , characterized in that the steering factor φ is calculated on the basis of a ratio A / B, where A is derived from F _VR and F _HL , or from F _VL and F _{H R is} determined and B is determined from F _VL , F _HL , F _VR , F _HR .

As already discussed in the introduction, solutions are known in the prior art which derive steering commands on the basis of a shift in weight when cornering is initiated. In an exemplary implementation of the solutions, A is determined from two contact foot forces on one side of the tread, such as F _VL and F _HL , or F _VR and F _HR . This creates the problem that getting on or off can also erroneously be interpreted as a steering command which leads to undesired rotations of the passenger transport device.

In many sports, for example snowboarding, cornering is initiated by turning the hip. This corresponds to an intuitive and natural movement, so that in this invention solutions are developed which are set up to derive steering commands on the basis of this hip rotation. Compared to shifting weight, the movement of the hip rotation leads to a different distribution of the contact foot forces on the tread surface. Thus, in the present invention, A is preferably determined from two contact foot forces on a diagonal line of the tread, namely F _VR and F _HL , or F _VL and F _HR . As a result, getting on or off can no longer be interpreted as a steering command, so that unwanted movements of the passenger transport device can be avoided.

oder des Verhältnisses $\frac{F_{VL}+F_{HR}}{F_{VL}+F_{HL}+F_{VR}+F_{HR}}$

berechnet.Preferably, the steering factor is φ based on the ratio $\frac{{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{L.}}}{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{L.}}{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{R.}}}$

or the relationship $\frac{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{R.}}}{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{L.}}+{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{R.}}}$

calculated.

The at least four contact foot forces can preferably be detected or determined by at least four force sensors, the at least four force sensors preferably being strain gauges. The force sensors can also be FSR sensors or other sensors that are suitable for measuring or determining compressive or tensile forces.

The contact foot forces can either be measured directly or determined indirectly. In a possible embodiment according to the seventh aspect of the invention, the foot forces are not measured directly. Instead, the deformation of the vehicle due to the foot forces is measured using strain gauges. From this, the uprising foot forces can be reconstructed using mathematical methods. The sensors used are not limited to force sensors such as strain gauges or FSR sensors, they can also include other sensors such as optical sensors that measure physical deflection; Sensors that measure the hydraulic pressure in chambers in the vehicle; capacitive sensors; path-dependent sensors; or a combination of the above sensor types.

The recorded sensor data can be transmitted wired or wirelessly. In a further preferred embodiment, the detected sensor data are transmitted through at least one wireless interface, the at least one wireless interface being an optical interface, an inductive interface or a radio interface. A wireless interface can be used primarily in a foldable passenger transport device, whereby the risk of a cable kinking or breaking can be avoided by folding the passenger transport device.

The steering control unit is preferably also set up to determine a yaw rate Yaw _desired by the user of the passenger transport device based on the steering factor φ.

In a preferred embodiment, the steering control unit is set up to _{input the determined desired yaw rate Yaw desired} into a control loop, preferably in a closed PID control loop, which is set up to control the steering of the passenger transport device. The control loop can continuously counteract a deviation of the measured yaw rate from the desired yaw rate Yaw _desired.

The control unit is furthermore preferably set up to take into account additional data such as internal forces in the passenger transport _{device, speed of the passenger transport device, driving mode, etc. when determining the desired yaw.} Internal forces arise, for example, from the torque of a motor. The higher the engine torque, the more twisted the chassis, since the engine torque is introduced into the chassis at different points. These internal forces can also be measured by the sensors, but are not based on a steering command actually entered, so that these forces could falsify the result of the yaw rate determination. According to one embodiment of the invention, such force influences are removed _{when determining Yaw desired.}

In a further preferred embodiment, the passenger transport device comprises at least two ground contact units, each of which is driven by a motor, the control loop being set up to adjust the torque difference between the motors of the at least two ground contact units in order to enable the passenger transport device to be steered.

As already discussed, steering of the passenger transport device is preferably implemented by increasing the torque of the motor for one wheel on one side for acceleration and at the same time reducing the torque of the motor for the other wheel on the other side. The control loop is preferably set up to set the difference between the torques on the basis of the steering command.

According to an eighth aspect of the present invention, the object is achieved by a method for steering control of a passenger transport device with at least one step surface, which serves as a standing surface for a user while using the passenger transport device, comprising: measuring or determining at least four contact foot forces of the two feet of the user in each case for the front and rear foot regions on the tread area, the at least four contact foot forces being: contact foot force front left F _VL , contact foot force front right F _VR , contact foot force rear left F _HL , contact foot force rear right F _HR ; Calculating a steering factor φ on the basis of a ratio A / B, with A being determined from F _VR and F _HL , or from F _VL and F _HR , and B being determined from F _VL , F _HL , F _VR , F _HR .

Further preferred embodiments of the method according to the eighth aspect of the invention are claimed in claims 38-44.

According to a ninth aspect of the present invention, the object is achieved by a people transport device comprising at least one step surface and a steering control unit according to one of claims 29-36.

• 1 Eine schematische Darstellung eines Zustandsautomats für eine Personentransportvorrichtung gemäß einer Ausführungsform der vorliegenden Erfindung,
• 2 Ein Flussdiagram für ein Schalten in verschiedene Zustände des Zustandsautomats der 1 mit verschiedenen Übergangsbedingungen gemäß einer Ausführungsform der vorliegenden Erfindung,
• 3 Eine schematische Darstellung der Drehmomentänderung der Motoren der Bodenkontakteinheiten einer Personentransportvorrichtung mit einem das verfügbare Drehmoment der einzelnen Motoren nicht überschreitenden Lenkungsbefehl,
• 4 Eine schematische Darstellung der Drehmomentänderung der Motoren der Bodenkontakteinheiten einer Personentransportvorrichtung mit einem das verfügbare Drehmoment der einzelnen Motoren überschreitenden Lenkungsbefehl gemäß einer Ausführungsform der vorliegenden Erfindung,
• 5 Eine schematische Darstellung der physikalischen Eigenschaften eines elektrischen Motors,
• 6 Eine schematische Darstellung verteilter Aufstandsfußkräfte auf einer Trittfläche einer Personentransportvorrichtung,
• 7 Eine beispielhafte Darstellung eines ermittelten Steuerungsfaktors auf Basis einer Gewichtsverlagerung,
• 8 Eine beispielhafte Darstellung eines ermittelten Steuerungsfaktors nach einer Lösung in der vorliegenden Erfindung auf Basis einer Hüftdrehung, und
• 9 Eine schematische Darstellung eines Regelkreises zur Lenkungssteuerung einer Personentransportvorrichtung nach einer Ausführungsform der vorliegenden Erfindung

The invention is explained in more detail below on the basis of preferred exemplary embodiments with reference to the accompanying drawings. Show it:

• 1 A schematic representation of a state machine for a passenger transport device according to an embodiment of the present invention,
• 2 A flowchart for switching to different states of the state machine of the 1 with different transition conditions according to an embodiment of the present invention,
• 3 A schematic representation of the change in torque of the motors of the ground contact units of a passenger transport device with a steering command that does not exceed the available torque of the individual motors,
• 4th A schematic representation of the change in torque of the motors of the ground contact units of a passenger transport device with a steering command exceeding the available torque of the individual motors according to an embodiment of the present invention,
• 5 A schematic representation of the physical properties of an electric motor,
• 6th A schematic representation of distributed contact foot forces on a step surface of a passenger transport device,
• 7th An exemplary representation of a determined control factor based on a weight shift,
• 8th An exemplary illustration of a determined control factor according to a solution in the present invention on the basis of a hip rotation, and
• 9 A schematic representation of a control loop for steering control of a passenger transport device according to an embodiment of the present invention

State machine of a people transportation device

1 FIG. 13 shows a state machine for a passenger transportation device according to an embodiment of the present invention. The passenger transport device is preferably a Segway or an e-board with a step surface and two ground contact units, the passenger transport device comprising a control unit, which in turn comprises a balance control unit and a steering control unit. The control unit of the passenger transport device preferably has three states: a) An idle state 10 , in which both the balance control unit and the steering control unit are deactivated, b) a balance state 20th in which the balance control unit is activated and the steering control unit is deactivated, and c) an active state 30th in which both the balance control unit and the steering control unit are activated.

The switching between the above-mentioned states is preferably carried out by the in 1 displayed foot movements of the user triggered, which define the transition conditions between the individual states.

It should be noted that a person skilled in the art can also define and add further states as required.

In order to enable automatic switching between the states, the passenger transport device should be able to recognize the foot movements of the user. The foot movements are preferably recorded or determined by one or more force sensors, but other sensors for recording the foot movements are also conceivable. When determining the transition conditions, other parameters can also be of importance, e.g. the weight of the user on the step surface, one or more contact foot forces of the user on the step surface as well as their time derivatives, the speed of the passenger transport device, etc.

In addition, preferably varying environmental conditions such as environmental influences or user properties are also to be taken into account when determining the transition conditions. These are, for example, the user's weight, the nature of the ground, lateral forces when cornering, a foot size, a shoe sole, a slight delay in ascending detection, a slight delay in ascending detection, the environmental resistance of the sensors to temperature, moisture, etc.

The circuit between the states is shown in 2 for example clearly illustrated by a flow chart. How out 2 can be seen, the circuit is triggered by the fulfillment of one or more transition conditions.

As discussed above, the user weight initially plays an important role in determining the transition conditions. The user weight is preferably also recorded or determined by one or more force sensors built into the passenger transport device, such as, for example, strain gauges or FSR sensors. The measured values of the strain gauges are preferably filtered with a digital FIR filter (“Finite Impulse Response” filter) with a cut-off frequency of 8 Hz, which can reduce the sensitivity of the controller to bumps and edges, for example. A so-called “RiderWeightFactor” (rider weight factor) can preferably be introduced for better, easier further use of this variable. This normalizes the measured weight to a reference weight of e.g. 80 kg. In this way, the control system can be quickly adapted to a different driver weight. In order to also be able to recognize light drivers, the threshold value from which the user is perceived as present must be low enough. At the same time, however, the value must be above the values achieved by a pure sensor drift in order to prevent accidental activation of the passenger transport device, whereby it should be avoided, for example, to recognize cats or dogs that have jumped onto the step surface as users and thus endanger the traffic. The threshold value for activating the drive train was preferably set at 32 kg in iterative tests, which corresponds to a “RiderWeightFactor” of 0.4.

When determining the user weight and the distributed contact foot forces, the influence of the variations in the different shoe sizes should preferably also be taken into account. In order to achieve robustness in relation to different shoe sizes, the foot forces can be introduced evenly into an underside made of aluminum with integrated strain gauges, for example through an upper shell of the tread surface made of carbon fiber-reinforced plastic. Thus, the flow of force is almost identical for the majority of the expected foot sizes (statistically approx. 85% of the shoe sizes are between 36 and 44), so that the control system is robust against variations in shoe sizes.

If the measured total weight of the user on the step is below a predefined threshold value, the drive train is deactivated. The control unit of the passenger transport device thus switches to the “idle state”.

If the measured total weight of the user exceeds the threshold value, the balance control unit should be switched on. However, by checking further transition conditions, it is preferably also determined whether the control unit should switch to a balancing state or to an active state. If the measured weight distribution of the user is in the middle, the control unit switches to the “active state”, whereby both the balance control unit and the steering control unit are activated.

If the measured weight distribution of the user is not centered, a further check is preferably carried out to determine whether the speed of the passenger transport device exceeds a predefined threshold value and whether cornering is currently being initiated. If the result of this test is “no”, the steering control unit should be deactivated. Thus, the control unit switches to the “balancing state” so that unwanted rotary movements when climbing or dismounting can be avoided. If the result of this test is "yes", the control unit switches to the "active state".

Particularly noteworthy is the "speed above threshold and cornering" check, which can increase the robustness against lateral accelerations that can result from cornering, for example. In spite of the uneven weight distribution, the steering is not deactivated when the vehicle is at a certain speed and a curve is being driven at the same time. The detection of whether a curve is being driven can be done, for example, by comparing the rate of rotation of the vertical axis gyroscope with a previously defined threshold value.

Prioritization of the balance control via the steering control

As already discussed in the introduction to the description, the steering control competes with the balance control of a self-balancing passenger transport device. In order to maintain the stability of the passenger transport device and to avoid tipping over, the control unit in the present invention is set up to prioritize the balance control over the steering control.

3 and 4th each show a schematic representation of the change in torque of the motors of the ground contact units of a passenger transport device with a steering command according to an embodiment of the invention, with FIG 3 the steering command has not exceeded the available torque of a motor, while in 4th the steering command has exceeded the available torque of a motor.

In 3 and 4th the torque change of the motors is shown by several partial figures, with the torque of the motor of the left ground contact unit and the torque of the motor of the right ground contact unit being shown together in each partial figure. As previously discussed, to enable steering, the torque of the motor for one ground contact unit is preferably increased for acceleration and at the same time the torque of the motor for another ground contact unit is reduced. In order to maintain the balance, however, the torque of the motor for one ground contact unit and the torque of the motor for the other ground contact unit must be increased or reduced by the same amount, so that the average torque of the motors remains unchanged and thus the balance of the passenger transport device is not disturbed.

Partial figure a) the 3 shows the required torque of the respective motors for the balance control, when a user, for example, accelerates along a straight line, whereby the same torque M required _balance for the left motor or the right motor for the balance control, so that the average torque of the two motors equals M _equilibrium . The maximum torque M _{Max and the torque M steering} reserve still available for the steering of the respective motors are also shown.

If the user still wants to initiate cornering during this acceleration, the motors are loaded even further. Partial figure b) the 3 shows a theoretical change in torque with the steering command to the left and c ) the 3 shows the actually resulting torque of the motors with the steering command.

In order to follow the steering command to the left, ideally the torque of the right motor is to be increased by a torque M _steering command required after the steering command and the torque of the left motor is to be reduced _{by the M steering command.}

From the partial figure b) the 3 it can be seen that M _steering command has not exceeded the available torque M _{steering reserve of the right motor.} So how can c ) the 4th shows the torque of the right engine around with no problem M _steering command can be increased and the torque of the left motor _{can be reduced by M steering} command, the average torque of the two motors remaining unchanged, so that the balance control is not affected.

4th consists in an analogous manner of several sub-figures. From the partial figure a) the 4th can be seen that compared to 3 more torque for balance control in 4th is needed. This corresponds, for example, to the case that a user accelerates very quickly along a straight line and the motors are thus loaded with a very large proportion of their maximum torque, for example 90%, are already loaded. If a user wants to initiate cornering in this situation, which e.g. requires an increase in the torque of the right motor by 20% and a reduction in the torque of the left motor by 20%, the right motor should theoretically be 90% + 20% = 110 % are charged as part of figure b) the 4th represents. However, an engine load over 100% is not possible. Thus, the torque of the right motor increases to a maximum of 100% of the maximum torque M _Max , while the torque of the left motor is reduced to 90% - 20% = 70%. As a result, the average torque of the motors changes from 90% to 85%, disturbing the balance control and possibly causing overturning.

In order to solve the problem, the control unit according to the exemplary embodiment of the invention is set up to prioritize the equilibrium control, the solution being for example in c ) and d) the 4th is shown. c ) shows the determined torque change of the respective motors according to an embodiment of the present invention and d ) shows the resulting torque of the motors.

If the additional torque M _steering command required after the steering command exceeds the available torque M _{steering reserve of} a motor, the control unit is preferably set up to increase the torque of the motor by a different torque M _{steering control} , and the torque of another motor by this different torque M _{Reduce steering control} , where M _{steering control is} equal to or less than the available torque M _{steering reserve} . As a result, the average torque of the motors remains unchanged, so that the stability of the people mover can be maintained.

The following explains how the maximum torque of an electric motor can be determined.

The torque of an electric motor is proportional to the current flowing through it. This applies to both common DC motors and modern permanent magnet synchronous motors. This means that the maximum motor torque is proportional to the maximum current that can flow through the motor at the current operating point. The relationship between current and torque is defined by a so-called "machine constant""C × φ": I _Mot × C × φ = M _Mot .

At the same time, an induced voltage (U _BEMF ) is generated in the windings of the motor, the voltage of which is proportional to the speed of the motor. If the revolutions per minute (rpm) of the motor is zero, the voltage is also zero.

Also, conventional motors have a certain electrical resistance (R _ESR ) in their copper windings that causes a voltage drop proportional to the current flowing through them. They also have an inductance (L _ESL ), which in some situations can lead to a voltage drop.

The motor is connected to a servo amplifier to control the movements. The servo amplifier generates an output voltage that is input to the motor (Uin). The maximum possible output voltage of the servo amplifier is known (U _inMAX ) and depends, for example, on the voltage of the mains or the battery voltage.

The physical properties of the engine can be as in an in 5 model shown.

The maximum possible current through the motor windings can be calculated using the following equation: $${\mathrm{I.}}_{\mathrm{M.}\mathrm{A.}X}=\frac{U_{in\mathrm{M.}\mathrm{A.}X}-U_{\mathrm{L.}}-U_{\mathrm{B.}\mathrm{E.}\mathrm{M.}\mathrm{F.}}}{{\mathrm{R.}}_{\mathrm{E.}\mathrm{S.}\mathrm{R.}}}$$

This in turn is used to calculate the maximum torque of the motor according to the following equation: $${\mathrm{M.}}_{max}={\mathrm{I.}}_{\mathrm{M.}\mathrm{A.}X}\times \mathrm{C.}\times \phi$$

This shows that a number of factors can influence the maximum available torque of the engine. In particular, the input voltage of the servo amplifier, the resistance of the windings and the motor speed are important factors that must be taken into account.

• • die Motordrehzahl steigt => das verfügbare Motordrehmoment sinkt;
• • die Wicklungstemperatur steigt => der Wicklungswiderstand steigt => das verfügbares Motordrehmoment sinkt;
• • die Batteriespannung sinkt => das verfügbare Motordrehmoment sinkt;
• • die Wicklungsinduktivität steigt => das verfügbare Motordrehmoment sinkt;
• • Die Innentemperatur des Servoverstärkers steigt => das verfügbare Motordrehmoment sinkt;
• • Die Leistungsfähigkeit des Akkus sinkt => das verfügbare Motordrehmoment sinkt.

There are generally the following correlations (not necessarily linear) between a few important parameters and the available engine torque:

• • the engine speed increases => the available engine torque decreases;
• • the winding temperature increases => the winding resistance increases => the available motor torque decreases;
• • the battery voltage drops => the available motor torque drops;
• • the winding inductance increases => the available motor torque decreases;
• • The internal temperature of the servo amplifier increases => the available motor torque decreases;
• • The capacity of the battery sinks => the available motor torque sinks.

Steering of a passenger transport device

As already presented in the introduction to the description, steering during cornering of a self-balancing transport device, such as a Segway or an e-board, can be controlled according to the prior art by shifting the user's weight. That is, if a user wants to initiate cornering, he leans his body when initiating cornering in the direction of the center of the curve, and a steering command is given on the basis of the resulting shift in weight.

In 6th four distributed contact foot forces are exemplified for the front and rear foot regions of a user on a step surface 150 a person transport device, the four foot forces shown are: uprising foot force, front left F _VL , uprising foot force, front right F _VR , uprising foot force, rear left F _HL, and uprising foot force, rear right F _HR .

In an example implementation of the solutions in the prior art, a steering factor steering factor φ 'was formed on the basis of a weight shifting method as follows: $$\phi \text{'}=1-2\times \frac{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{L.}}}{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{L.}}+{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{R.}}}$$

7th shows an example of the resulting values of the steering factor φ 'due to various foot movements of a user. It is clearly evident that climbing on or off using the weight shifting method is also falsely recognized as a steering command, which can lead to unwanted turns.

In order to solve the problem, another method is developed within the scope of this invention which derives a steering factor on the basis of a hip rotation movement. As already mentioned, in many sports, such as snowboarding, cornering is initiated by turning the hip. This corresponds to an intuitive and natural movement, which is therefore used to derive a steering command within the scope of the invention.

According to the invention, a steering factor φ is formed, for example, as follows: $$\phi =1-2\times \frac{{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{L.}}}{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{L.}}+{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{R.}}}$$

In 8th the resulting values of the steering factor φ are represented by various foot movements of a user. It can be seen that an ascent or descent with the solution in the present invention can no longer be recognized as a steering command, so that undesired rotations can be avoided.

_{The yaw rate Yaw desired desired} by the user can be determined on the basis of the determined steering factor φ. The steering control unit of the passenger transport device is then set up to _{input the determined yaw rate Yaw desired} into a control loop, which is exemplified in FIG 9 is illustrated. In order to increase the sensitivity of the control, the determined yaw rate Yaw _{desired should} preferably be increased with a gain (gain) Kp. A limiter 170 is preferably to be used for the output of the amplifier 160 to regulate down to a certain maximum value. In order to improve the driving behavior, one or more transfer functions are preferred 180 provided, whereby it is possible with the one or more transfer functions to make the sensitivity of the steering, for example speed-dependent. Thus, the control becomes more agile, for example by increasing the steering deflections at low speeds, and safer and more pleasant by reducing the steering deflections at high speeds.

The adjusted desired yaw rate Yaw _desired is then entered as a setpoint in a PID controller 190 entered, the current yaw rate w _{z of} the passenger transport device as an actual value in the PID controller 190 is entered. The PID controller is preferably set up to continuously adjust the torques of the motors in accordance with the control deviation so that an appropriate torque difference is generated between the motors on both sides of the passenger transport device in order to enable the desired steering.

Conclusion

It should be noted that all of the logic functions of a control unit of a passenger transport device can be implemented in one or more microcomputers within the scope of the invention. In a particular embodiment of the invention, the acquisition of the sensor data and the execution of the functions described are distributed over a large number of microcomputers, which are preferably electronically connected.

The acquisition of the analog sensor values takes place via evaluation electronics (not described in detail) with a measuring amplifier, an analog-digital converter, a frequency counter or a combination thereof. It is also conceivable to use sensors that already output a digital signal via an interface.

The complete processing of the code of the state machine and the calculation for the steering is preferably carried out cyclically with a frequency between 20 and 100 Hz.

The sampling frequency ("sample rate") of the sensors can be a multiple of the frequency of the state machine and the calculations, which enables the use of digital filters.

The sensors used do not necessarily have to be in the step surface of the passenger transport device or in the vicinity of the user's feet, but can be installed in all areas. Possible locations include, but are not limited to: Internal structural components, external structural components, in joints and in ground contact units.

It should also be noted that the present invention is not limited to self-balancing vehicles. The present invention can also be used for means of transport with several wheels and at least one step surface on which a user can stand, such as transport vehicles in warehouses, for example.

Claims (45)

Control unit for a passenger transport device, comprising a balance control unit and a steering control unit, the control unit being set up to switch to at least the following operating states: a. an idle state (10) in which both the balance control unit and the steering control unit are deactivated, b. a balance state (20) in which the balance control unit is activated and the steering control unit is deactivated, and c. an active state (30) in which both the balance control unit and the steering control unit are activated. Control unit for a passenger transport device according to Claim 1 , characterized in that the control unit is set up to switch from one operating state to another operating state when at least one transition condition from one operating state to the other operating state is met. Control unit for a passenger transport device according to Claim 2 , characterized in that the passenger transport device has at least one step surface that serves as a standing surface for a user while using the passenger transport device, the control unit being set up to detect a foot movement of the user, with the at least one transition condition being met by at least one detected foot movement of the user is enabled. Control unit after Claim 3 , characterized in that the control unit is set up to detect the at least one foot movement by one or more force sensors. Control unit for a passenger transport device according to one of the Claims 2 - 4th , characterized in that the control unit is set up to determine the at least one transition condition on the basis of one or more of the following parameters: - the total weight of the user on the step surface, - at least one contact foot force of the user on the step surface, - at least one time derivative the total weight of the user on the step surface, - at least one time derivative of a contact foot force of the user on the step surface, - at least one factor determined from several contact foot forces of the user on the step surface, - at least one speed of the passenger transport device Control unit for a passenger transport device according to Claim 5 , characterized in that the at least one transition condition is defined by comparing the one or more parameters with in each case a predetermined threshold value. Control unit for a passenger transport device according to Claim 5 or Claim 6 , in which the control unit is set up to take into account one or more of the following additional parameters when determining the at least one transition condition: - at least one measured or estimated unevenness of the ground, - at least one acceleration of the passenger transport device, - at least one yaw rate of the passenger transport device, - the weight of the user . A method for controlling a passenger transport device which comprises a balance control unit and a steering control unit, the method comprising switching into at least the following operating states: a. an idle state (10) in which both the balance control unit and the steering control unit are deactivated, b. a balance state (20) in which the balance control unit is activated and the steering control unit is deactivated, and c. an active state (30) in which both the balance control unit and the steering control unit are activated. Procedure according to Claim 8 , characterized in that switching from one operating state to another operating state is triggered in that at least one transition condition from one operating state to the other operating state is met. Procedure according to Claim 9 , characterized in that the passenger transport device has at least one step surface that serves as a standing surface for a user while using the passenger transport device, the method detecting a foot movement of the user, wherein the at least one transition condition can be met by at least one detected foot movement of the user becomes. Procedure according to Claim 10 , characterized in that the foot movement is detected by one or more force sensors. Method according to one of the Claims 9 - 11 , characterized in that the method comprises determining the at least one transition condition on the basis of one or more of the following parameters: - the total weight of the user on the step surface, - at least one contact foot force of the user on the step surface, - at least one time derivative of the total weight of the User on the step surface, - at least one time derivative of a contact foot force of the user on the step surface, - at least one factor determined from several contact foot forces of the user on the step surface, - at least one speed of the passenger transport device Procedure according to Claim 12 , characterized , characterized in that the at least one transition condition is defined by comparing the one or more parameters with a predetermined threshold value in each case. Procedure according to Claim 12 or 13th , the method also taking into account one or more of the following additional parameters when determining the at least one transition condition: at least one measured or estimated unevenness of the ground, at least one acceleration of the passenger transport device, at least one yaw rate of the passenger transport device, the weight of the user. Passenger transport device, comprising at least one step surface, which serves as a standing surface for a user while using the passenger transport device, and a control unit according to one of the Claims 1 - 7th . Control unit for a self-balancing passenger transport device, which has two or more ground contact units, which are each driven by a motor, wherein the control unit comprises a balance control unit for balance control and a steering control unit for steering control, the control unit being set up, if one for a desired steering and a simultaneous balance control required torque of the motor of a ground contact unit exceeds the maximum torque of the motor to prioritize the balance control over the steering control. Control unit for a self-balancing passenger transport device according to Claim 16 , characterized in that the control unit is set up to determine the maximum torque of the motor of a ground contact unit M _Max. Control unit for a self-balancing passenger transport device according to Claim 17 , wherein the control unit is set up to determine _{the maximum torque of the motor of a ground contact unit M Max} on the basis of at least one or more of the following parameters: a winding temperature of the motor, - a state of charge of at least one battery of the motor, - the capacity of the at least one battery of the motor, - a speed of the motor, - an internal temperature of a servo amplifier of the motor. Control unit for a self-balancing passenger transport device according to one of the Claims 16 - 18th , characterized in that the control unit is set up to determine a _{torque M equilibrium} required for the equilibrium control of the passenger transport device. Control unit for a self-balancing passenger transport device according to Claim 19 , characterized in that the control unit is set up to determine a torque of the motor M available for a steering steering _{reserve of} a ground contact unit, wherein: $${\mathrm{M.}}_{\mathrm{L.}enkunGsreserve}\le {\mathrm{M.}}_{\mathrm{M.}ax}-{\mathrm{M.}}_{GleicHGewicHt}.$$

Control unit for a self-balancing passenger transport device according to Claim 20 , characterized _{in that the control unit is set up to determine a torque M steering} command required for a desired steering according to a steering command, where: - if M _balance + M _steering command ≤ M _Max , the control unit is set up to set the torque of the motor a Ground contact unit on one side of the transport _device to increase m steering command, and the torque of the motor of a ground contact unit on the other side of the transport _device to reduce M steering command. - If M _balance + M _steering command> M _Max, the control unit is set up to increase the torque of the motor of a ground contact unit on one side of the transport device by a different torque M _{steering control} , and the torque of the motor of a ground contact unit on the other side of the transport device by to reduce the other torque M _{Lenkunassteuer, wherein} $${\mathrm{M.}}_{GleicHGewicHt}+{\mathrm{M.}}_{\mathrm{L.}enkunGssteuerunG}\le {\mathrm{M.}}_{\mathrm{M.}ax}.$$

A method for controlling a self-balancing passenger transport device which has two or more ground contact units each driven by a motor, the passenger transport device further comprising a balance control unit for balance control and a steering control unit for steering control, the method, if one for a desired steering and a simultaneous balance control required torque of the motor of a ground contact unit exceeds the maximum torque of the motor, the balance control prioritizes over the steering control. Procedure according to Claim 22 , characterized in that the method comprises determining the maximum torque of the motor of a ground contact unit M _Max. Procedure according to Claim 23 , characterized in that the maximum torque of the motor of a ground contact unit M _{Max is determined} at least on the basis of one or more of the following parameters: a winding temperature of the motor, a state of charge of at least one battery of the motor, the performance of at least one battery of the motor , - a speed of the motor, - an internal temperature of a servo amplifier of the motor. Method according to one of the Claims 22 - 24 characterized in that the method further comprises _{determining a torque M equilibrium} required for the equilibrium control of the passenger transport device. Procedure according to Claim 25 , characterized in that the method further comprises determining a torque of the motor M, which is available for a steering, of a steering _{reserve of} a ground contact unit, wherein: $${\mathrm{M.}}_{\mathrm{L.}enkunGsreserve}\le {\mathrm{M.}}_{\mathrm{M.}ax}-m_{GleicHGewicHt}.$$

Procedure according to Claim 26 , characterized _{in that the method comprises determining a torque M steering} command required for a desired steering according to a steering command, wherein: - if M _balance + M _steering command ≤ M _Max, the method further comprises the following steps: increasing the torque of the motor to a ground contact unit one side of the transport device around M _{steering command} , Reducing the torque of the motor of a ground contact unit on the other side of the transport device by M _{steering command} ; - If M _balance + M _{steering command} > M _Max, the method further comprises the following steps: increasing the torque of the motor of a ground contact unit on one side of the transport device by a different torque M _{steering control} reducing the torque of the motor of a ground contact unit on the other side of the transport device by the other torque M _{steering control} where $${\mathrm{M.}}_{GleicHGewicHt}+{\mathrm{M.}}_{\mathrm{L.}enkunGssteurunG}\le {\mathrm{M.}}_{\mathrm{M.}ax}.$$

Passenger transport device, comprising two or more ground contact units, each driven by a motor, and a control unit according to one of the Claims 16 - 21 . Steering control unit for steering a passenger transport device, which has at least one step surface (150) that serves as a standing surface for a user when using the passenger transport device, the steering control unit being set up for this, based on a steering factor φ, which is derived from at least four measured or determined contact foot forces each for the front and rear foot regions of the user on the at least one tread surface (150) are calculated to control the steering of the passenger transport device, the at least four contact foot forces being: contact foot force front left F _VL , contact foot force front right F _VR , contact foot force rear left F _HL , Rear right foot force F _HR , characterized in that the steering factor φ is calculated on the basis of a ratio A / B, A being determined from F _VR and F _HL , or from F _VL and F _HR , and B from F _VL , F _HL , F _VR and F _{HR is} determined. Steering control unit according to Claim 29 , characterized in that the steering factor φ is based on the ratio $\frac{{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{L.}}}{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{L.}}+{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{R.}}}$

or the relationship $\frac{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{R.}}}{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{L.}}+{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{R.}}}$

is calculated. Steering control unit according to Claim 29 or Claim 30 , characterized in that the at least four contact foot forces are detected or determined by at least four force sensors, the at least four force sensors preferably being strain gauges. Steering control unit according to Claim 31 , characterized in that the detected sensor data are transmitted through at least one wireless interface, the at least one wireless interface being an optical interface, an inductive interface or a radio interface. Steering control unit according to one of the Claims 29 - 32 , characterized in that the steering control unit is set up _{to determine a yaw rate Yaw desired} by the user of the passenger transport device based on the steering factor φ. Steering control unit according to Claim 33 , characterized in that the steering control unit is set up _{to determine a setpoint based on the determined yaw rate Yaw desired} and input it into a control loop, preferably in a closed PID control loop, which is set up to control the steering of the passenger transport device. Steering control unit according to Claim 33 or Claim 34 , characterized in that the control unit is also set up to take into account additional data such as internal forces in the passenger transport _{device, speed of the passenger transport device, driving mode, etc. when determining Yaw desired.} Steering control unit according to Claim 34 or Claim 35 , characterized in that the people transport device comprises at least two ground contact units, which are each driven by a motor, wherein the control loop is set up to adjust the torque difference between the motors of the at least two ground contact units in order to enable steering of the people transport device. A method for steering control of a passenger transport device with at least one step surface, which serves as a standing surface for a user while using the passenger transport device, comprising: measuring or determining at least four contact foot forces of the two feet of the user for the front and rear foot regions on the step surface, wherein the at least four contact foot forces are: contact foot force front left F _VL , contact foot force front right F _VR , contact foot force rear left F _HL , contact foot force rear right F _HR , - calculation of a steering factor φ based on a ratio A / B, where A is derived from F _VR and F _HL , or is determined from F _VL and F _HR , and B is determined from F _VL , F _HL , F _VR , F _HR . - Controlling a steering of the passenger transport device based on the steering factor φ. Procedure according to Claim 37 , characterized in that the steering factor φ is based on the ratio $\frac{{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{L.}}}{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{L.}}+{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{R.}}}$

or the relationship $\frac{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{R.}}}{{\mathrm{F.}}_{V\mathrm{L.}}+{\mathrm{F.}}_{H\mathrm{L.}}+{\mathrm{F.}}_{V\mathrm{R.}}+{\mathrm{F.}}_{H\mathrm{R.}}}$

is calculated. Procedure according to Claim 37 or Claim 38 , characterized in that the at least four contact foot forces are detected or determined by at least four force sensors, the at least four force sensors preferably being strain gauges. Procedure according to Claim 39 , characterized in that the detected sensor data are transmitted through at least one wireless interface, the at least one wireless interface being an optical interface, an inductive interface or a radio interface. Method according to one of the Claims 37 - 40 , characterized in that the method further comprises: determining a yaw rate Yaw _desired by the user of the passenger transport device based on the steering factor φ. Procedure according to Claim 41 characterized in that the method further comprises: determining a target value based on the determined yaw rate Yaw _desired ; Entering the setpoint in a control loop, preferably in a closed PID control loop, which is set up to control the steering of the passenger transport device. Procedure according to Claim 41 or Claim 42 , characterized in that the method takes into account additional data such as internal forces in the passenger transport device, speed of the passenger transport device, driving mode, etc. _{when determining the desired yaw.} Procedure according to Claim 42 or Claim 43 , characterized in that characterized in that the people transport device comprises at least two ground contact units, each driven by a motor, wherein the control loop is set up to adjust the difference in torques between the motors of the at least two ground contact units in order to steer the people transport device enable. Passenger transport device, comprising at least one step surface and a steering control unit according to one of the Claims 29 - 36 .

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