WO2017186911A1

WO2017186911A1 - A vehicle, a continuously variable transmission system, a control method, and a computer program product

Info

Publication number: WO2017186911A1
Application number: PCT/EP2017/060195
Authority: WO
Inventors: Elias Van Wijk; Peter Willy C VANDEMOORTELE
Original assignee: Punch Powertrain N.V.
Priority date: 2016-04-28
Filing date: 2017-04-28
Publication date: 2017-11-02
Also published as: BE1023741B1; CN109416401A; CN109416401B

Abstract

Continuously variable transmission (CVT) system for a vehicle, comprising a variator having two friction elements. A first friction element is coupled to a second friction element through a torque transmitting member, wherein the clamping force or pressure of at least one friction element onto the torque transmitting member is adjustable. The CVT system further comprising a controller arranged for retrieving information representative of an upcoming road condition, wherein the controller is further arranged for, on the basis of the retrieved information, adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member.

Description

Title: a vehicle, a continuously variable transmission system, a control method, and a computer program product FIELD OF THE INVENTION

The invention relates to a system and method for controlling a vehicle transmission by use of retrieved road condition information.

BACKGROUND TO THE INVENTION

A vehicle transmission provides controlled application of engine power by conversion of speed and torque from a power source. A continuously variable transmission (CVT) is an automatic transmission allowing change through a continuous range of effective gear ratios. An input from a prime mover can be used to deliver variable output speeds and torques, while the input can be maintained at a constant angular velocity. A CVT can comprise a variator for providing a mechanical power transmission, wherein the variator may comprise two friction elements, wherein a first friction element is connected to a second friction element through a torque transmitting member, such as a (push) belt. A first conical pulley and a second conical pulley may be provided, each connected to a shaft. Each shaft can comprise a fixed and an axially moveable sheave. A flexible member such as but not limited to a chain or a belt, wherein a belt may be a segmented steel V- belt, clamped between two pairs of conical sheaves of the pulleys may be arranged, wherein the gap between the sheaves and thereby the belt running radius can be adjusted by axial movement of the moveable sheave. The variator can change its gear ratio continuously.

The CVT efficiency may, among other things, be influenced by the mechanical system efficiency, actuation system losses and control strategy. When the vehicle is driving at constant moderate speed, the actuation system may take a large part of the power consumption and also have a profound effect on the efficiency of the variator. If the clamping forces in the variator are lowered, the efficiency of the variator may improve and the power required by the actuation system can decrease, resulting in an improvement of the efficiency of the CVT. The clamping forces in the variator are also important for the mechanical system efficiency. Consequently, lowering the clamping forces may reduce, at least in part, both the actuation system losses and mechanical system losses.

CVT efficiency can already be at the level of manual transmission (MT), however there is still room for improvement since current CVT losses can be higher compared to MT. The main reason for the lower efficiency of CVTs is the high clamping force necessary to transfer the engine torque. In order to prevent slip of the torque transmitting member, or belt slip, the clamping forces in CVTs is usually at all times higher than needed for 'normal' operation, i.e. situation without disturbances and/or torque peaks. Higher clamping forces can therefore induce higher losses in both the hydraulic and the mechanical system, for example due to increased pump losses, extra mechanical load on the variator parts resulting in increased friction losses. The higher clamping forces may also reduce the endurance of the belt because of increased wear, since the net pulling force in this element is larger than strictly required (for normal operation). Also as a result of the clamping forces, heavier components may be required and therefore arranged in the CVT system, which may also have a detrimental effect on the power density.

Because of this, the clamping force of the torque transmitting member (e.g. push belt) has an important influence on the efficiency of a CVT. In fact, the efficiency of a CVT may largely be determined by the clamping force. Therefore, lower clamping forces can lead to better efficiencies.

Lowering the variator clamping forces can be advantageous for the fuel consumption because of the decrease in power consumed by the hydraulic pump of the CVT and decrease of friction power losses in parts of the the variator. The reduced clamping forces can also be beneficial for the power density since the push belt stresses will decrease. However, lowered clamping forces may also increase the risk of belt slip, for instance in case of torque peaks, or slow or delayed hydraulic responses.

In order to be able to cope with unexpected torque peaks created by driving on a road with bad and/or different road conditions, a higher clamping force can be employed as the minimum required to avoid belt slipping. This

precautionary measure is necessary since the road conditions for the vehicle are not known. However, if no such over-clamping is used in the CVT, disturbances may cause severe slip events which could potentially damage the variator of the CVT. It is known to use the measurements of the actual torque or of the slip in the variator in order to use a clamping force with a lower safety margin, i.e. lowered clamping force and/or no over-clamping, while reducing the risk of excessive slip.

Also, in known CVT control systems, sensors for measuring wheel speed or acceleration may also be used by the control system so as to make an

appropriate adjustment of the clamping force.

US2005/159,259 discloses a method for detection of road irregularities by means of the gradient of the summed up difference between measured wheel speed and the weighted mean value of the wheel speed, so as to adjust the contact pressure on the pulleys of a variator on the basis of the detected condition of the road. In such feedback control systems, the detection of the road irregularities may come too late, so that during "normal" driving conditions (e.g. driving conditions without road irregularities), the clamping force needs to be sufficiently large in order to be able to resist against unexpected high shocks and/or torque peaks as a result of the vehicle driving over the road irregularities. Actually, in feedback control systems using wheel speeds, incidents on the wheels are detected. However, there is no guarantee that the incidents on the wheels originate from the road irregularities. The wheel speed incidents are linked to the road condition. Although said control system can be implemented with relatively simple means, the accuracy and provided certainty tends to be also limited.

SUMMARY OF THE INVENTION

It is an object of the invention to provide for a system, a method and vehicle that obviates at least one of the above mentioned drawbacks, while maintaining the advantages.

It is a further object of the invention to improve the efficiency of a CVT system and/or a vehicle comprising said CVT system.

It is a further object of the invention to provide an efficient control strategy for a CVT, wherein risk of slipping in the variator of the CVT is reduced when the vehicle encounters different road conditions, e.g. slipping of the torque transmitting member in the variator, such as a pushbelt (cfr. "belt slipping").

The CVT system may comprise a variator having two friction elements wherein a first friction element is coupled to a second friction element through a torque transmitting member. A clamping force or pressure of at least one friction element onto the torque transmitting member is adjustable. The CVT system further comprises a controller which is arranged for retrieving information representative of an upcoming road condition. Further, the controller is arranged to adjust, on the basis of the retrieved information, the clamping force or pressure of the at least one friction element onto the torque transmitting member.

The information representative of the road condition can relate to road conditions such as hill information, weather conditions, snow, rain, slope of the ground or road, objects on the road, potholes, kerbs, road irregularities, pavement, road roughness, traffic, etc. It will be appreciated that the information

representative of the road condition can include a numerical value for a road condition. It is also possible that the information representative of the road condition is encrypted or encoded. It is also possible that the information representative of the road condition includes a classification of the road condition. Unless otherwise specified, herein road condition information refers to information representative of the road condition.

In the variator, power can be transmitted from a first pulley to the second pulley by means of a torque transmitting member. The torque transmitting member may be a pushbelt arranged between the first pulley and second pulley, wherein power is transmitted by means of friction between the push belt and pulley sheaves. Therefore, an increased efficiency can be obtained by control of the pressure or clamping force for the torque transmitting member or push belt of a CVT, using upcoming road condition information retrieved by the controller.

As has already been mentioned above, the efficiency of a CVT transmission is largely determined by the clamping force of the torque transmitting member (e.g. pushbelt). Optimizing towards lowest non-slipping clamping force leads to low hydraulic pressures. However, in order to be able to handle unexpected torque peaks created by different road conditions, a higher clamping force is usually employed to obtain a minimum clamping force required to avoid belt slipping when encountering different road conditions. The higher clamping force may have a detrimental effect on the efficiency, resulting in a higher fuel consumption of the vehicle. According to the current invention, the upcoming road conditions for a vehicle is retrieved by the controller. Thereby (relevant) road conditions to be experienced by driven wheels of the vehicle, end hence by the CVT may be predicted and processed in order to evaluate the effect on the CVT system of the vehicle before this effect is actually experienced. For example, upcoming road conditions in front of a forward moving vehicle comprising a CVT system can be used to determine the (relevant) road conditions in advance and increase, if required, the clamping force or pressure of at least one friction element onto the torque transmitting member, taking into account the retrieved road conditions. As a result, the use of a general reserve, safety margin or over-clamping for the clamping force or pressure can be avoided or at least greatly reduced, which may improve the efficiency of the CVT system. Another advantage is that the risk for adverse effects such as belt slipping in the CVT system can be reduced, which may improve the lifetime and/or reduce maintenance costs.

Accordingly, rather than using direct measurements for the detection of slipping conditions and feedback, e.g. when the wheels of a driving vehicle reach a pothole on the road, the condition of the road surface can be identified by the controller beforehand, so as to predict the required clamping force and, if necessary, adjust the clamping force in order to avoid belt slipping in the CVT ahead of time or simultaneously with the road condition being experienced.

Optionally, the controller is arranged for predicting a change in variator input and/or output torque on the basis of the retrieved road condition information, and adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member according to the predicted torque change. The adjustment of the clamping force or pressure in the variator may be performed prior to or simultaneously with the torque change occurring.

As a result, an assessment of the road condition relevant for the vehicle can be obtained in advance. For instance, information related to road irregularities on the road and/or road roughness can be detected ahead of shock events, so as to be able to increase the clamping force in time. In this way, the vehicle can be configured to employ a lower clamping force during "normal" driving conditions, which may result in a reduced fuel consumption of the vehicle. The driving comfort can also be improved. Furthermore, wear and tear can be reduced, thereby also increasing the lifetime of the vehicle and its components. Thus, a higher clamping force including a reserve can be avoided if the road conditions of the driving route of the vehicle is predicted and/or anticipated by said vehicle. In order to realize this, the road conditions are obtained in advance. The retrieved data can then be analyzed by the controller in order to recognize and take into account the road conditions ahead.

Optionally, the controller is arranged for predicting a moment on which the variator input and/or output torque will change on the basis of the retrieved road condition information, and adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member according to the predicted torque change. The adjustment of the clamping force or pressure in the variator may be performed prior to or simultaneously with the predicted moment.

A vehicle comprising a CVT according to the current invention may employ a lower reserve and may also keep the reserve low so that efficiency losses can be avoided. This effect can be particularly profound when a vehicle is driving on normal road conditions with a conventional reserve or safety margin for the clamping force or pressure in the variator, arranged to handle unexpected torque peaks. The controller of the CVT system may be arranged to perform pre-control of clamping force or pressure in the variator before impact for making sure that the required clamping level is reached at the time of impact or even before.

Advantageously, post-control of clamping force or pressure in the variator after impact can also be performed by the controller in order to make sure that the required clamping force level or pressure level in the variator is kept long enough, e.g. so as to prevent belt slip due to fading out of torque oscillations.

Optionally, the controller is arranged for adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member if the predicted change in variator input and/or output torque exceeds a

predetermined threshold level.

Optionally, the controller is arranged for retrieving the road condition information from a detector for detecting a road condition.

The upcoming road conditions can be determined from data obtained from a detector such as an essentially non-intrusive remote-sensing system for recognition of relevant road condition features. A detector may be a sensor system including one or more sensors configured to sense information about an environment in which the vehicle is located or other information which may be important for the vehicle, such as future road condition information in a future path of a (driving) vehicle. In this way, changing road conditions can be timely identified. Although the detector can be arranged to obtain (relevant) upcoming road condition information for the vehicle, said information may also be obtained from a memory, a network, a data transmission, a cloud, other vehicles, other entities, and/or sensor systems arranged for other systems, such as for example sensors arranged for providing autonomous capabilities for self-driving vehicles. Consequently, the controller may, based on the retrieved upcoming road condition information, dynamically adjust the actuation of friction elements of the variator of the CVT. Furthermore it is possible to use both data coming from the remote- sensing system provided by a detector and from the cloud, for the purpose of better anticipating the road conditions for the vehicle.

Optionally, the detector is arranged for determining the road condition in front of the vehicle.

Optionally, the detector is placed in the vehicle. For instance, the detector may be arranged in the front of the vehicle so as to provide a front detection.

Optionally, the controller is arranged for being wirelessly

communicatively connected to the detector. The detector may be arranged in or on the vehicle while being wirelessly in communication with the controller. However, alternatively or additionally, upcoming road condition information may be retrieved from a detector arranged on another structure.

A wireless communication system can be arranged to provide the wireless communication between the controller and the detector. The controller may be configured to be wirelessly coupled to one or more other vehicles, sensors, or other entities, either directly or via a communication network. To this end, the wireless communication system may include an antenna and a chipset for communicating with the other vehicles, sensors, or other entities either directly or over a wireless interface. The chipset or wireless communication system in general may be arranged to communicate according to one or more other types of wireless communication (e.g., protocols) such as Bluetooth, communication protocols described in IEEE 802.11 (including any IEEE 802.11 revisions), cellular technology (such as GSM, CDMA, UMTS, EV-DO, WiMAX, or LTE), Zigbee, dedicated short range communications (DSRC), and radio frequency identification (RFID) communications, among other possibilities. The wireless communication system may take other forms as well.

Optionally, the controller is arranged for communicating with the detector, the detector being placed in a further vehicle, preferably driving in front of the vehicle including the continuously variable transmission system.

Optionally, the controller is arranged for communicating with the detector, the detector being placed stationary relative to the road.

Optionally, the controller is arranged for communicating with a network for retrieving the road condition information.

The data from the sensors on the vehicle which help to obtain an estimation of the local road condition can be communicated with the cloud, or other networked system, in order to build a database of the road conditions of roads. This data can then be used by other vehicles which have access to the cloud. Also, direct communication between different vehicles may be possible in order to obtain an improved and/or faster view of the road conditions relevant for the vehicle. Also, previous data can be stored locally and/or in the cloud, in order to improve the efficiency of determining the road condition.

In an advantageous embodiment, the road condition information can be stored into a cloud and/or a server so as to be able to summarize and provide or share adequate information on a local and global road condition to the outside world, whether it is a next vehicle, a local server connected with a central database or an internet service. Advantageously, the information retrieved from the cloud by the controller can be used in combination with a detector to increase the clamping levels of the CVT variator, if necessary or required. The communication can happen through any telecommunications device and, e.g. standard, protocol, wherein the information can be sent and received from local servers and other vehicles and also local measuring devices at (the side of) the road. A local server can gather information about the local roads. This local server can be connected with a global server, gathering road data of a big region, where some data analytics algorithms can be used to determine more accurately the road condition data as well the impact on the vehicles in use, regarding clamping force. The kind of information that can be interchanged between the vehicle and the cloud may be: GPS location, weather condition, road type, IRI classification, objects (e.g. potholes, kerbs, etc), object characteristics (height, width, location), camera pictures, wheel speed information, tyre pressure information, accelerometer sensor information, internal CVT speed sensor information, clamping force information, and so forth. Many other possibilities are possible. In some examples, the data can be summarized for communication.

Optionally, the network includes a memory storing the road condition information.

Optionally, the network communicates with one or more detectors arranged for determining the road condition, the one or more detectors being placed stationary relative to the road and/or in vehicles.

Optionally, the system includes a network server arranged for providing the road condition information to the controller. The network server can be arranged for receiving from the controller an indication of a location of the controller, and for transmitting to the controller road condition information relating to the location of the controller.

Optionally, the detector includes an optical system, such as a digital camera, a radar system, a lidar system, and/or an acoustic system.

The detector may be an essentially non-intrusive remote-sensing system arranged at least partially on a front portion of the vehicle, so as to define at least a scanning field in front of the vehicle, or at least in front of the driven wheel(s) of the vehicle, i.e. the driving direction of the vehicle. It is appreciated that other scanning fields than a front scanning field may also be arranged, e.g. lateral, bottom, rear and/or 360° scanning fields. The detector may be a remote- sensing system comprising a camera. The retrieved data from the camera, radar, lidar and or acoustic sensor input may be used to determine the road conditions in advance in order to increase the system pressure in the CVT if required by the detected road conditions. In normal road conditions, the vehicle may drive with a system pressure of the CVT kept relatively low, so that unnecessary reserve of the pressure is not needed, thereby reducing or avoiding the efficiency loss coupled with the use of a pressure reserve. Optionally, the controller is arranged for analyzing an image provided by the camera, for features indicative of the road condition.

Features which are indicative of the road condition may include among other things: hill information, weather conditions, snow, rain, slope of the ground or road, objects on the road, potholes, kerbs, road irregularities, pavement, road roughness, etc.. The feature can be relevant for the control of the clamping force or pressure in the variator of the CVT system.

The camera may be any camera (e.g., a still camera, a video camera, etc.) configured to capture images of the environment or surrounding area in which the vehicle is located. To this end, the camera may be configured to detect visible light, or may be configured to detect light from other portions of the spectrum, such as infrared or ultraviolet light. Other types of cameras are possible as well. The camera may comprise a two-dimensional sensor, or may have a three-dimensional spatial range. The camera may be, for example, a range detector configured to generate a two-dimensional image indicating a distance from the camera to a number of points in the environment. Other range detecting techniques or devices may be used in combination with the camera. In an exemplary embodiment, the camera may be configured to use a structured light technique in which the vehicle illuminates an object in the environment with a predetermined light pattern, such as a grid or checkerboard pattern and uses the camera to detect a reflection of the predetermined light pattern off the object. Based on distortions in the reflected light pattern, the vehicle may be configured to determine the distance to the points on the object. The camera can be arranged behind a front windshield of a vehicle. However, in other embodiments the camera may be mounted elsewhere on the vehicle, either inside or outside the vehicle.

The process of the classification of the road condition information may further involve the controller determining a probability distribution (e.g., a Gaussian distribution) of possible conditions associated with the detected road condition information. Such a probability distribution may take the form of a discrete probability distribution, continuous probability distribution, and/or mixed continuous- discrete distributions. Other types of probability distributions are possible as well. Optionally, the system further includes a wheel speed sensor, and the controller arranged for adjusting the clamping force or pressure of the at least one friction element onto the member further on the basis of the detected wheel speed.

Other measurement or sensing systems such as wheel speed sensors, accelerometers, CVT internal speed sensor, tire pressure sensors can be used in combination with the detector according to the current invention, to get an even more accurate analysis of the local road condition.

Optionally, the system further includes a tyre pressure sensor, and the controller arranged for adjusting the clamping force or pressure of the at least one friction element onto the member further on the basis of the detected tyre pressure.

Optionally, the system further includes an artificial horizon sensor, and the controller arranged for adjusting the clamping force or pressure of the at least one friction element onto the member further on the basis of the detected horizon.

Optionally, the system further includes a steering angle sensor, and the controller arranged for adjusting the clamping force or pressure of the at least one friction element onto the member further on the basis of the detected steering angle.

The invention further relates to a vehicle comprising a CVT according to the present invention.

Optionally, the vehicle may further comprise the detector according to the present invention.

The invention further relates to a network server arranged for transmitting information representative of a road condition to a vehicle including a continuously variable transmission system according to the invention.

Optionally, the network server is arranged for receiving information representative of a road condition from one or more sensors. These sensors can be mounted in a vehicle including a CVT according to the invention. The sensors can also be placed elsewhere. Optionally, the network server is arranged for receiving information representative of a clamping force or pressure from a vehicle including a CVT according to the invention.

Optionally, the network server is arranged for receiving from a vehicle an indication of a location of that vehicle, and for transmitting to the vehicle information representative of the road condition at and/or near a location of the vehicle.

Optionally, the network server has associated therewith a memory storing information representative of road conditions. The memory can be a database. The content of the memory can be dynamic in that it can be updated regularly or continuously with information representative of road conditions obtained from sensors, such as sensors mounted to vehicles including a CVT according to the invention, or sensors positioned elsewhere.

The invention further relates to a method for operating a CVT system for a vehicle, including a variator with a first friction element and a second friction element coupled through a torque transmitting member. The method comprises setting an optimal clamping force or pressure of at least one friction element onto the torque transmitting member; retrieving upcoming road condition information; and adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member on the basis of the retrieved road condition information.

It is known that the electronic control unit of a vehicle can learn driving habits over a certain number of drive cycles, wherein some driving parameters (e.g. fuel-air mix) and aspects of the operation of the vehicle are adjusted accordingly. An adaptive transmission control may e.g. adapt the shift characteristics to the driver's wish and the driving situation. Such adaptive systems may be used in combination with the current invention so as to not only adapt to driving habits but also adapt to the conditions of the road ahead, by which a more comfortable experience for the passengers of the vehicle may be provided, next to an increased energy efficiency.

The vehicle may comprise sensors such as a Global Positioning System (GPS) device, an inertial measurement unit, a radio detection and ranging (e.g. radar) device, a laser rangefinder and/or light detection and ranging (e.g. lidar) device, a camera, and/or actuators configured to modify a position and/or orientation of the sensors. The sensor system may include additional sensors as well, including, for example, sensors that observe internal systems of the vehicle, e.g. gas monitor, a fuel gauge, an engine oil temperature, et cetera. Other sensors are possible as well. The CVT system according to the present invention may use one or more of the sensors of the sensor system of the vehicle so as to enable the controller of the CVT system to retrieve upcoming road condition information. The sensor data can also be shared, for instance wirelessly with other entities.

The controller of the CVT system may be arranged to retrieve road condition information from different sources, such as through a detector (e.g.

sensors, camera, radar, laser, lidar, etc.) e.g. mounted on the vehicle itself, through a cloud (e.g. wireless communication to a network), through other vehicles in wireless communication with the vehicle, and/or through sensor systems used by the driving control system in an auto-assist, autonomous vehicle or self-driving vehicle. Therefore, the sensors used for self-driving vehicles can partially or completely take the place of the detector according to the current invention. The controller of the CVT system can obtain information ahead from a shock event so as to be able to increase the clamping force or pressure on time and resist against unexpected high shocks in the variator.

Sensors for obtaining road condition information may be expensive, especially if accurate sensors for obtaining high quality measurements are arranged. However, scanning units may be used to map a road or an area. The retrieved road condition information can be stored in a database. The scanning unit can be a dedicated mapping system. The data can be retrieved by the vehicle comprising the CVT system according to the current invention. The controller may be arranged to use said retrieved data as a main source for retrieving road condition information, or arranged to use the data to improve the prediction of the upcoming road information. Also, it is possible that road condition

data/measurements from a plurality of vehicles are combined to improve the road condition information in a database, so that the data can be continuously improved and kept up-to-date. The road condition information can then be provided as a service to individual vehicles and be retrieved by the controller of the vehicles. Furthermore, road classification systems may be used by the controller. For instance, roads can be classified in different classes. Using such a road

classification system, the size of the data transfer to the controller can be significantly reduced. In one embodiment, the detector is only used if certain conditions are met. For instance, it is possible that certain roads are well known from previous analysis or from a network, so that scanning of the road by a detector can be turned off. The controller of CVT system may determine when the detector is used for scanning the road condition. For this purpose, a certainty and/or quality parameter can be appointed to the retrieved road condition information by the controller of the CVT system.

The controller of the CVT system may be arranged to obtain data from one or more sources, wherein sources can service-based which may include a subscription system, while other sources may provide an open access. In one embodiment, the controller will first check for the available sources for providing the upcoming road information, after which the controller can select a plurality of sources, if available, and make an assessment of the road condition by taking into account the selected sources. In an other embodiment, a plurality of the vehicles may be arranged to be in communication with each other to exchange information related to, among other things, the road condition. Sensory data from an autonomous vehicle and/or self- driving vehicle which does not comprise the CVT control system according to the current invention, can at least partially be utilized by the vehicle comprising the CVT control system.

Further, the CVT system according to the current invention may comprise a non-transitory computer-readable medium, which has program instructions stored thereon that are executable by at least one processor to provide the functionality described by the method herein.

In the present disclosure, the variator in the shown embodiments includes two friction elements and a torque transmitting member, however, other combinations of friction elements and torque transmitting members are possible.

It will be appreciated that any of the aspects, features and options described in view of the CVT system apply equally to the vehicle and the described methods. It will also be clear that any one or more of the above aspects, features and options can be combined.

BRIEF DESCRIPTION OF THE DRAWING

The invention will further be elucidated on the basis of exemplary embodiments which are represented in a drawing. The exemplary embodiments given by way of non-limitative illustration. It is noted that the figures are only schematic representations of embodiments of the invention that are given by way of non-limiting example.

In the drawing:

Fig. 1 shows a schematic diagram of an embodiment of a CVT system; Fig. 2 shows a schematic diagram of a control strategy for a CVT system;

Fig. 3 shows a schematic top plan view of a vehicle and its surrounding area;

Fig. 4a shows a schematic side view of a vehicle and its surrounding area;

Fig. 4b shows a schematic top plan view of a vehicle and its surrounding area;

Fig. 5a shows a schematic top plan view of a vehicle and its surrounding area;

Fig. 5b shows a schematic top plan view of a vehicle and its surrounding area;

Fig. 6 shows a schematic side view of vehicles;

Fig. 7 shows a schematic diagram of a control strategy for a CVT system;

Fig. 8 shows a flow chart of an embodiment of a method; and

Fig. 9 shows a schematic diagram of an example of a control strategy for a CVT system 1.

DETAILED DESCRIPTION

Fig. 1 is a schematic diagram of an example of a continuously variable transmission, CVT, system 1, in accordance with an exemplary embodiment of the present invention. The CVT system 1 provides a controlled application of engine power coming from a motor 11, such as an engine. In this example, the motor 11 is coupled to an input shaft 18a of the CVT via a clutch 11a. The CVT converts rotational speed and torque from the motor 11, presented at the input shaft 18a of the CVT to a (different) rotational speed and/or torque at an output shaft 18b of the CVT. The CVT comprises a variator 2 for providing a mechanical power

transmission, wherein the input from a prime mover 18a is used to deliver variable output speeds and torques to wheel(s) 13 of a vehicle. The input from the input shaft may be maintained at a constant angular velocity. The variator 2 comprises a primary cylinder 3 and a secondary cylinder 4. Further, the variator 2 comprises two friction elements 15, 16, namely, a first friction element 15 and a second friction element 16, wherein the first friction element 15 is connected to the second friction element 16 through a torque transmitting member 17, such as a pushbelt 17. Other torque transmitting members 17 are possible, such as a V-belt, a chain or a flexible member. In this example the first friction member 15 is embodied as a first conical pulley. In this example the second friction member 16 is embodied as a second conical pulley. The first conical pulley 15 is connected to the input shaft 18a. The second conical pulley 16 is connected to the output shaft 18b. The first conical pulley 15 includes two sheaves 19a, 19b, in this example a fixed sheave 19a axially fixed in relation to the input shaft 18a, and a moveable sheave 19b axially movable in relation to the input shaft 18a. The second conical pulley 16 includes two sheaves 19c, 19d, in this example a fixed sheave 19c axially fixed in relation to the output shaft 18b, and a moveable sheave 19d axially movable in relation to the output shaft 18b. The torque transmitting member 17, in this embodiment shown as a pushbelt 17, which may be a segmented steel V-belt, a chain, a flexible member, etc. for example, is clamped between the two pairs of conical sheaves 19a, 19b and 19c, 19d of the pulleys 15, 16. The gap between the sheaves and thereby the pushbelt 17 running radius can be adjusted by axial movement of the moveable sheave 19b, 19d of the first pulley 15 and/or the second pulley 16 of the variator 2. In this example, the variator 2 can change its gear ratio continuously. The CVT system 1 is actuated using hydraulic power coming from a hydraulic actuation system 6. The hydraulic actuation system 6 has a first hydraulic pressure line 7 which is connected to the first friction element 15 and a second hydraulic pressure line 8 which is connected to the second friction element 16. The clamping force or pressure of the first friction element 15 and/or the second friction element onto the torque transmitting member 17 can be adjusted and controlled by use of an electronic engine control unit 14 (ECU) or a separate transmission control unit 5 (TCU, also known as transmission control module TCM). In this embodiment the TCU 5 is connected with the hydraulic actuation system 6. A digital image processing control unit (DIPCU) can be provided which operates as a central control unit, processing all kind of data coming from sensors, including the retrieved upcoming road condition information. The output of the DIPCU can be used by the TCU 5. However, the DIPCU can also be part of the TCU 5. The DIPCU can be arranged to allow processing of data. The TCU 5 can be arranged to control actuators, such as the moveable sheaves, of the CVT system 1. The hydraulic system 6 can comprise hydraulic components arranged for converting actuator signals coming from the TCU 5 into hydraulic pressures. The pressures may include a first and second pressure. The first pressure and the second pressure are converted into clamping forces on the first pulley 15 and the second pulley 16 through the first hydraulic line 7 and the second hydraulic line 8, respectively.

The TCU or controller 5 can receive input from the cloud (such as road condition, weather condition, objects, GPS location, traffic information, etc.), from sensors and/or from the DIPCU. Based on a predicted road condition, the controller 5 can set the appropriate clamping force or pressure of the friction element 15 and/or the friction element 16. The controller 5 can reconstruct the road

environment, and send a more accurate update to the cloud.

The upcoming road information may be received by the controller 5 through a wired connection or a wireless connection. In case of wireless data communication, a wireless connection device may be arranged to transfer signals through mobile data transfer protocols such as 3G, 4G, 5G, etc. However, other wireless protocols such as WiFi (e.g., a wireless communication conforming to the IEEE 802.11 standard or other transmission protocol) may also be employed to obtain a wireless communication. A combination of wireless protocols is possible.

The CVT system 1 according to the current invention may also be employed in autonomous vehicles and/or self-driving vehicles. Various computing systems and sensor systems are used in autonomous vehicles for the transportation from one location to another. A driving control system of the autonomous vehicle may be arranged to receive by one or more cameras and/or sensors a plurality of data points corresponding to an environment of the autonomous vehicle. For example, lidar sensors may be employed to obtain a three-dimensional (3D) point cloud. A lidar system may use a beam to detect and measure the distance between the vehicle and an object from the reflection of the beam. Lidar works independent of ambient light, so that a 3D-map of the surrounding may be retrieved even in poor lighting conditions (e.g. night). Although accurate, a lidar system typically is more expensive than for instance a system comprising one or more cameras and/or radar.

The driving control system may also be arranged to collect information which is indicative of the road condition within the vicinity of the vehicle. For instance, the 3D point cloud of the scanned region by the lidar sensors of the surroundings of the vehicle can be used by the controller of the CVT system 1 to retrieve upcoming road condition information for the vehicle. The retrieved upcoming road condition information can be used by the controller 5 to adjust the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17.

The controller 5 of the CVT system 1 can be arranged to retrieve information regarding upcoming road condition using data coming from sensors which are already available and provided for the driving control system of autonomous vehicles and/or self-driving vehicles. As a result, the CVT system 1 may not require the arrangement of extra sensors and/or detectors, by which the costs may significantly be reduced.

The control of clamping force can be an addition to the normal calculation and/or control of clamping forces and pressures in the variator 2. If the required clamping force or pressure by normal control is sufficiently high, the controller may determine to not change said clamping force or pressure in the variator 2. If it is too low, the controller 5 may determine to change the required clamping force or pressure.

Other components coupled to or comprised in the CVT system 1 may include, an oil pump 12, further sensors (e.g. one or more speed sensors 9, lever position sensors 9a, ABS speed sensors 9b, turbine speed sensor 9c, pressure sensors 10, etc.), a drive-neutral-reverse, DNR, set 9d, et cetera. The components of the CVT system 1 may be arranged to work in an interconnected fashion with each other and or with other components coupled to respective systems. In other examples, the CVT system 1 may include more, fewer, or different systems, and each system may include more, fewer, or different components. Additionally, the systems and components shown may be combined or divided in any number of ways. Fig. 2 shows a schematic diagram of a control strategy for a CVT system 1. Certain ambient conditions 20 for a vehicle comprising a CVT system 1 may be relevant for the operation and control of the CVT system 1. For example, a surface of a road or ground on which a vehicle is travelling, or is going to travel, can be relevant for the control of the CVT system 1. Therefore, the control strategy for the CVT system 1 will acquire information 21 representative of the road condition. The information representative of the road condition can relate to road conditions such as hill information, weather conditions, snow, rain, slope of the ground or road, objects on the road, kerbs, road irregularities, pavement, road roughness, traffic (e.g. Traffic Message Channel (TMC) data, or the like), etc. It will be appreciated that the information representative of the road condition can include a numerical value for a road condition. It is also possible that the information representative of the road condition is encrypted or encoded. It is also possible that the information representative of the road condition includes a classification of the road condition. Unless otherwise specified, herein road condition information refers to information representative of the road condition.

This information is then sent to the controller or TCU 5 of the CVT system 1. According to the example of Fig. 2 the controller comprises two units namely a clamping force calculation unit which is arranged to determine and/or calculate the clamping force and a pressure setting unit which is arranged for setting the pressure commands. The controller 5 is arranged to predict torque peaks in the CVT based on received information representative of the road condition, and to adjust the pressure settings to be sent to the hydraulic system 6. The hydraulic system 6 is arranged to control friction elements 15, 16 based on the pressure setting signals coming from the controller 5. In this way, the hydraulic system 6 will adjust the hydraulic pressure or the clamping force of the at least one friction element 15, 16 onto the torque transmitting member 17 in function of the predicted torque. In this example, control of the first friction element 15 may target the clamping torque of the primary part of the variator, while control of the second friction element 16 may target the clamping torque of the secondary part of the variator. The controller 5 may be arranged to determine a desired setpoint for hydraulic pressure or clamping force for the first friction element 15 and the second friction element 16 separately. On the basis of the vehicle speed and the location of the recognized objects, the time-to-impact of a road condition for all wheels can be calculated. This can be performed for the front wheels, but also for the rear wheels of the vehicle. Even when the wheels are not directly connected to the CVT transmission shafts, the bump can cause a vehicle unbalance, which may also be noticed at the other wheels, and at the CVT transmission shafts. A path determination can be performed for all the wheels, which may be based on the vehicle speed and the steering wheel angle signal. When an object or road irregularity is on the path of a wheel, the time-to-impact can be calculated. Left and right wheels can have their own predicted paths. The detected objects can be generalized to behave for both wheels. However, also the impact for each of the wheels can be considered and calculated separately.

Based on the properties of the features (e.g. objects) of the road, the severity of the impact can be calculated. For example an ongoing kerb can be worse than an offgoing kerb, a bigger or deeper pothole can have more impact, et cetera. The same object hitting the non-driven wheels (e.g. rear wheels) can have less impact than when hitting the driven wheels (e.g. front wheels). Difference in left and right wheels may lead to a different kind of impact. The vehicle speed may play an important role for the impact prediction by the controller 5. The same bump in the road can have a higher severity of impact at higher vehicle speeds.

Fig. 3 shows a schematic top plan view of a vehicle 24 and its surrounding area 25. In this example the vehicle 24 comprises a CVT system 1. In the surrounding area 25, different irregularities and objects 26, 27, 28 in the road condition have been detected and identified by the CVT system 1. The vehicle 24 comprises four wheels, i.e. two front wheels 29, 30 and two rear wheels 31, 32. In this example the vehicle turns left, so that the front wheels 29, 30 are turned. The controller 5 may predict the paths 33, 34, 35 and 36 of the individual wheels 29, 30, 31 and 32, respectively. The irregularities and objects 26, 27, 28, e.g. their location, location relative to the wheels, size, shape, etc., form part of the road condition information. The controller 5 may then, on the basis of this retrieved road condition information predict an impact— here an impact of the presence of the irregularities and objects 26, 27, 28 - on the torque in the CVT, e.g. the torque at the input shaft 18a and/or output shaft 18b of the CVT. On the basis of the predicted impact, the controller 5 then adjusts the clamping force or pressure of the at least one friction element onto the torque transmitting member in the variator 2 of the CVT system 1, if necessary. In this example, the paths 33, 34 and 36 of respectively wheels 29, 30 and 32 are predicted by the controller 5 to not encounter irregularities 26, 27 or objects 28 on the road in the surrounding area 25 of the vehicle 24. However, path 35 of wheel 31 is predicted to come across an object 28. The controller 5 can predict torque (peaks) based on the predicted encounter and control the pressure or clamping force in at least one of the friction elements 15, 16 of the variator 2.

A local vehicle environment can be determined in the form of a surrounding area 25. In an embodiment the monitoring range can be

approximately 7.5 meter in front of the vehicle, and approximately 2 meter behind the vehicle. Other ranges can be used and/or the ranges can be adjustable by use of actuators which may be manually and/or automatically controlled by the controller 5.

In an example, the controller 5 may be arranged to build a two- dimensional map of the road in front, under and behind the vehicle 24. When a new frame, e.g. a camera image, is available for analysis, the frame can be added at the front of the existing map, and a frame at the end of the existing map corresponding with a rear of the vehicle can be deleted. However the frames can also be saved in a memory and/or database. This process may result in a complete map of the environment of the vehicle 24, in relation to the location of all wheels 29, 30, 31, 32 of the vehicle 24. In this map, the detected features or relevant properties of the road condition such as but not limited to pave, asphalt, rain, snow, etc., or any kind of object can be indicated.

Fig. 4a shows a schematic side view of a vehicle 24 and its surrounding area, the vehicle comprising a CVT system 1. The vehicle 24 according to this example comprises a detector 38, wherein the controller 5 of the CVT system 1 is arranged for retrieving the road condition information from the detector 38. In this example, the detector 38 is arranged for determining the road condition in front of the vehicle 24. The detector 38 is also placed in the front of the vehicle 24, thereby creating a forward scanning area 39 on the ground or road 37. The road condition information in the forward scanning area 39 is recorded and analyzed by the detector 38. In this example, the controller 5 may be arranged for being wirelessly communicatively connected to the detector 38.

The controller 5 receives upcoming road condition information from the detector 38 and adjusts on the basis of the received road condition information the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17. The controller 5 is arranged for predicting a change in variator 2 input and/or output torque on the basis of the retrieved road condition information, and adjusting the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17 according to the predicted torque change.

The controller 5 can be arranged for predicting the moment on which the variator 2 input and/or output torque will change on the basis of the retrieved road condition information by the detector 38. For this, the distance between the forward scanning area 39, the contact point of each wheel 29, 30, 31, 32 with the ground 37 can be of importance. The speed of the vehicle 24 in the driving direction 40, and the predicted and/or estimated wheel paths 33, 34, 35, 36 for each wheel of the vehicle 24, may be important. The adjustment of the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17 according to the predicted torque change can be performed prior to or

simultaneously with the predicted moment by the controller 5 of the CVT system 1.

In this example, the detector 38 comprises an optical camera 38 arranged for making images. The camera 38 may be arranged to perform image processing. For this purpose, the camera 38 may comprise hardware, such as an application-specific integrated circuit ASIC, so as to perform image processing of the captured images. A digital processing control unit (DIPCU) may be arranged to allow processing of data. The DIPCU may be a central control unit, arranged to process all kind of imaging devices, including image processing dedicated for an embodiment according to the current invention. The output of the image processing may be used by the TCU 22. Note that the DIPCU may be part of the TCU. The TCU input unit 22 may be arranged to receive input signals of measurements of the road conditions coming from the camera 38. Further, the TCU output device 23 may be arranged so as to generate and/or send out control or output signals based on the input measurements, wherein the control signal or output signal takes into account a prediction of torque peaks. The pressure of two friction members 15, 16 of a variator 2, e.g. pulley clamping force, can then be controlled by the hydraulic system 6, based on the predicted torque peaks.

The camera 38, arranged for capturing an image of a part of the road 37 ahead of the vehicle 24 in the path of the driving direction 40 of the vehicle 24 and in front of the vehicle 24, may comprise a lens system arranged to capture one or more images by the camera 38. Further, this image is transferred into electronic signals by a digital image sensor. According to some embodiments the image processing step may comprise basic techniques, such as e.g. white-balance correction, sharpening, and/or contrast enhancement. Alternatively, or

additionally, digital image processing may be performed by software. A digital processing control unit (DIPCU) can be arranged to transmit raw captured images from the camera 38 into a specified record with all kind of road properties already classified, and make the results available for the TCU 5.

The algorithms involved in image processing may result in a certain calculation time needed to calculate road condition information on the basis of one or more frames. In order to reduce the calculation time the size, or resolution, of the frames may be chosen based on the actual vehicle speed. In an advantageous embodiment, higher vehicle speeds may lead to larger frames, or lower resolution frames. Based on one image, a part of the road may be reconstructed. The process may be repeated in time so as to build up a road environment frame-by-frame. It is also possible that road condition information is determined from a plurality of frames. Then inter-frame differences may be used for determining road condition information. Furthermore, object recognition algorithms can be applied. In some embodiments the detector 38 can be a stereo optical camera with near infrared view.

In another example, the object recognition algorithm may employ object recognition in order to identify kerbs, potholes and other types of objects. In case of a kerb or pothole, the height, width, and/or location can be identified. Further, for a kerb, it may also be relevant to determine whether the kerb is ongoing or offgoing. Further, relevant properties in identifying the road condition can be an

International Roughness Index (IRI) classification and/or pavement classification. Different distances L1-L4 are shown in Fig. 4a, wherein LI is the horizontal distance between the location of the detector 38 and the contact point of the front wheels 29, 30 with the ground or road 37. L2 is the horizontal distance between the contact point of the front wheels 29, 30 with the ground 37 and a front side of the vehicle 24. L3 is the horizontal distance between the front side of the vehicle 24 and a first field of view edge 42. L4 is the distance between the first field of view edge 42 and a second field of view edge 43. In an example, LI may be approximately 1 meter; L2 approximately 1 meter; L3 approximately 4 meter; and L4 approximately 4 meter. Other configurations are possible.

The sensors of the detector of the CVT system 1 may be manually and/or automatically adjustable by the controller 5 or another control system such as a driving control system in driving-assisted, autonomous vehicles and/or self- driving vehicles. For instance, when the detector comprises a camera, the detector may also comprise additional actuators so as to adjust the field of view of the camera. The adjustment can be automatically based on vehicle speed and/or ambient conditions surrounding the vehicle, such as mist, rainfall, snow, et cetera. The controller 5 may be arranged to detect whether the field of view of the detector 38 (or camera in this embodiment) is obstructed, e.g. as a result of another vehicle in the vicinity blocking at least part of the field of view. In case that the detector 38 is not able to obtain road condition information, the controller 5 can return the

CVT to a safe mode of operation, wherein a safety margin of the clamping force or pressure in the variator is employed, so as to reduce the risk of encountering undetected road conditions and to prevent belt slip. If the controller 5 detects other vehicles in the vicinity of the vehicle 24, which may provide the controller 5 with road condition information relevant for the path of the vehicle 24 on the road 37, the vehicle 24 may also take this information into account.

The controller 5 may be configured to determine an expected adjustment of pressure or clamping force on the basis of one or more of a location of changing road conditions, a direction of travel of the vehicle 24, the relative movement between retrieved road conditions and the vehicle 24, and the (expected) time of the individual wheels of the vehicle 24 encountering the retrieved road conditions. The predicted pressure or clamping force may be determined based on an analysis, a simulation and/or a comparison of the retrieved road condition data with one or more predetermined sets of road condition data. The one or more predetermined sets of road condition data may comprise training sets of data points built from other vehicles detecting road condition data in various scenarios.

For instance, each particular set of road condition data can be classified and labeled by the controller 5 based on various features and characteristics, such as identifying features of a road roughness (e.g., changing road conditions, road irregularities, potholes, obstacles, etc. while travelling on a road) and the driving activity of the vehicle 24. The retrieved road conditions and the prediction of the wheels of the vehicle 24 encountering the road conditions may performed using a clustering analysis, wherein a dataset from the retrieved road condition data is grouped in such a way that features or objects in the same group or cluster are more similar in some sense or another to each other than to those in other groups or clusters. Other types of analysis may also be used and may include one or more supervised and unsupervised learning-based algorithms. The analysis of the retrieved road condition information may be used to compute and/or determine a probability distribution of what road condition the vehicle 24 is going to encounter. From this analysis, abnormalities and/or changing road conditions which can be relevant for the CVT system 1 can be identified. The controller 5 may also compute the estimated or expected time of possible contact of each wheel with the upcoming road condition for the vehicle 24. If required, the expected necessary adjustment of the clamping force in the CVT system 1 may be performed in advance, or right on time. In this way, the controller 5 can avoid detrimental effects as a result of too low clamping forces or pressures in the variator, or avoid a lower efficiency of the CVT system 1 as a result of too high clamping forces in the variator of the CVT. In some embodiments, also a preferred direction of travel of the vehicle 24 can be determined based on the analysis of the retrieved road condition information by the controller 5. For example, a route for the vehicle can be proposed to a driver of the vehicle 24, or a route can be followed for instance in case of self-driving vehicles. Driving on a lane where the efficiency of the CVT can be increased, can be preferred. For instance, based on the retrieved road conditions a lane may be associated with an expected decrease in necessary clamping force and consequently a increased efficiency of the CVT system 1 of the vehicle 24 driving on said lane. In some embodiments, the controller 5 may determine features from the retrieved upcoming road condition data and provide each feature with a relevance score associated with the effect on the required clamping force in the CVT system 1 to avoid slipping in the torque transmitting member 17 while providing an advantageous efficiency. Such a relevance score may also be associated with the possibility of a wheel of the vehicle 24 encountering a road feature and/or the severity of such encounter.

The effect of a specific road condition (e.g. pothole) on the variator 2 of a CVT system 1 may also depend on the speed of the driving vehicle 24. Therefore, the controller 5 may not only determine the effect as a function of the driving speed of the vehicle, but may also suggest to change vehicle speed in order to reduce the impact of the retrieved road condition to the CVT system 1. The controller may be configured to provide instructions and/or suggest to adjust a speed of the vehicle 24 and/or a direction of travel of the vehicle 24, based on the expected necessary adjustment of the clamping force or pressure in the CVT system 1. Also, the data can be provided wirelessly to a cloud so that data can be shared with other users or vehicles. It is also possible to provide road condition information directly to other vehicles 24 driving in the vicinity of the vehicle 24 by using wireless

communication. Therefore, the controller 5 may not be limited to adjust the clamping force or pressure of at least one friction element 15, 16 onto the torque transmitting member 17 of a variator 2 of a CVT system 1 on the basis of the retrieved road condition information. In some embodiments, the controller 5 may suggest or instruct adjustment of other parameters, however, the adjustment may also be performed by another control system in communication with the CVT controller 5.

Fig. 4b shows a schematic top plan view of a vehicle 24 and its surrounding area. The vehicle with a CVT system 1 comprises the detector defining a field of view 41 in front of the vehicle. The optical camera 38 of the detector can be placed at a sufficient height so as to provide a far enough view with the right depth view. The forward scanning area 39 is defined by the distance L4 and the field of view angles a and 6. Actuators may be provided so as to adjust the angles a, 6. In this example, an irregularity 27 in the road condition (e.g. pothole) is detected in the forward scanning area 39 of the vehicle 24. Since the vehicle 24 drives or intends to drive forward in the driving direction 40, the path of the wheels 29, 30, 31, 32 can be determined. From Fig. 4b it can be seen that the coinciding paths 33, 35 of the front wheel 29 and rear wheel 31 of the vehicle will encounter the road irregularity 27 in the form of a pothole. The controller 5 retrieves the road condition information and predicts the effect of the pothole 27 on the CVT system 1 of the vehicle 24. If necessary (e.g. if the controller predicts that there is a risk for slipping of the torque transmitting member 17), the controller 5 of the CVT system 1 adjusts the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17. Preferably, the risk is assessed for each wheel 29, 30, 31 and 32 of the vehicle 24 based on predictions. However, it may be possible to employ a simplified embodiment wherein only the detection of the road condition in a scanned area is taking into account, regardless of the wheel paths. Alternatively or additionally, the controller 5 of the CVT system 1 may be arranged to work with probabilities for the wheel paths 33, 35 and 34, 36.

Fig. 5a and 5b show a schematic top plan view of a vehicle 24 and its surrounding area. The vehicle 24 comprises a detector 38 which provides a forward scanning area 39, which is formed by a projected field of view of the detector 38. In an example, the detector 38 may be an optical camera. When the vehicle is driving in the driving direction 40 it may encounter a region 44 with a noticeable change in road roughness, e.g. as a result of snow on the road, another type of road, an object on the road, et cetera. The paths 33, 34 of the front wheels 29, 30 of the vehicle 24 may be determined. The controller may predict the moment that the front wheels will encounter the region 44 if deemed necessary adjust the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17. . It will be appreciated that the simplified embodiment wherein only the detection of the road condition in the scanned area is taking into account regardless of the wheel paths will be very effective in view of road conditions formed by water (rain), snow, gravel or similar dispersed irregularities.

The controller 5 can determine a general road condition by use of information from the detector 38 and a classification on the type of road, the IRI classification and/or a pavement classification. The classification may already be performed by the DIPCU. In an embodiment, the controller 5 may monitor a range of approximately 20 meters in front and behind the vehicle. Advantageously, the controller 5 is arranged to not "rapidly" change from configurations of the clamping force or pressure in the variator for severe to less severe road conditions. For example, if one frame (of approximately 4 meter of road) indicates that the road condition is substantially improved, then this has to be confirmed several frames after each other or for a certain travelled distance, before the previous

configurations of the clamping force or pressure in the variator can be set to a new level. The image filtering may be applied on the images obtained by the camera. In an exemplary embodiment, the surface roughness can be classified in different classes, such as flat, asphalt, concrete, light pave, heavy pave, off-road, et cetera. Each class may require a different adjustment of the clamping force or pressure in the variator of the CVT system.

Fig. 5b shows a situation wherein the vehicle 24 is initially moving in the driving direction 40 and making a right turn. In this example, the path 33 of one of the front wheels is illustrated. The controller 5 can be arranged to determine such path and verify whether the predicted path will encounter a road condition which may require an adjustment of the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17. In this case a relevant road irregularity is detected. Although the predicted path 33 does not meet the road irregularity 27, the controller may take into account possible changes in the path, represented by a first boundary path 45 and a second boundary path 46. Relevant road conditions detected in the zone between the first boundary path 45 and the second boundary path 46, surrounding the path 33 may therefore be taken into account by the system to reduce risk and/or prevent pushbelt slip in the variator 2. Alternatively or additionally, a region surrounding a road irregularity may be inflated by the controller to reduce risk and/or prevent pushbelt slip in the variator 2. It will be appreciated that the field of view of the detector 38 may be coupled to a steering direction of the wheels, so as to, at least generally, look in the direction of the path of the vehicle.

Fig. 6 shows a side view schematic diagram of a vehicle 24 comprising a CVT system 1 encountering exemplary driving situations. Other scenarios are also possible. In the first case (a), the vehicle comprises a detector 38 retrieving road condition information in a forward scanning area 39 of the vehicle 24. The road condition information is analyzed and sent to the controller 5. In this case, a road irregularity 27 is detected which is anticipated by the controller 5 to require adjustment of the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17 in the variator 2 of the CVT system 1. Therefore, the controller 5 will adjust the clamping force based on the road irregularity 27. Further, after passing the detrimental road condition, the controller may readjust the clamping force based on new measurements in the forward scanning 39, if the controller 5 has determined that the scanned upcoming road condition information provided by the detector 38 allow such a configuration.

In the second case (b) in Fig. 6, two vehicles 24, 47 both comprising a CVT system 1 with a detector 38, are shown. Both vehicles are driving behind each other in the driving direction 40. There is sufficient distance between the two vehicles 24, 47 so that the detector 38 of the first vehicle 24 will be able to successfully scan a forward scanning area 39. The second vehicle 47 has detected a relevant road irregularity 27 in its forward scanning area 39. The controller 5 of the second vehicle 47 may therefore adjust, based on the retrieved upcoming road condition information, the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17 of the variator 2 of said vehicle 47. If the driving direction 40 is maintained, the first vehicle 24 will also encounter the road irregularity 27. The forward scanning area 39 of the detector 28 of the first vehicle 24 has not reached the road irregularity yet. However, the second vehicle 47 may already wirelessly communicate upcoming road condition information assessed by the detector 38 of said vehicle 47 to the CVT system 1 of the first vehicle 24, before the irregularity 27 is detected by the detector 38 of the first vehicle 24. The wireless communication of the road condition can be done directly, for instance by establishing a direct communication between the two vehicles 24, 47, or indirectly, for instance by using internet or cloud protocols. It will be appreciated that the second vehicle can also transmit clamping force or pressure information to the first vehicle. This clamping force or pressure information is then representative of the road irregularity 27.

The third case (c) in Fig. 6 is comparable with the second case (b). Here again, two vehicles 24, 47 are driving behind each other, both comprising a CVT system 1 and further a detector 38 for detecting road conditions in the forward scanning area 39 of the vehicle 24, 47. However, in this case, the distance between the two vehicles is limited, so that the point of view of the detector 38 of the first vehicle 24 is blocked by the second vehicle 47. As a consequence, the detector of the first vehicle 24 is not able to obtain a forward scanning area 39 of the ground 37 in front of the vehicle in order to obtain upcoming road information for said vehicle 24. In this case, the controller 5 of the vehicle 24 may not be able to assess the upcoming road condition so that, if no other sources can provide the upcoming road information, the controller 5 of the vehicle 24 may preemptively adjust the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17 of the variator 2 in the CVT system 1.

Alternatively or additionally, the controller 5 of the first vehicle 24 can receive the road information from the vehicle 47, which has already scanned the road before vehicle 24 without any limitation, and thus the controller 5 of vehicle 24 can, based on the received road information, adjust the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17 of the variator 2 in the CVT system 1. Alternatively, or additionally, the controller 5 of the first vehicle 24 can, in case of an autonomous, self-driving or assisted-driving vehicle, instruct a control system of said vehicle to increase the distance with the second vehicle 47, or in case of a driver operated vehicle suggest the driver to increase the distance and/or inform the driver that the point of view of the vehicle is blocked by the second vehicle 47. Also in this case, the second vehicle 47 may send road condition information to the first vehicle 24, if possible, as in the second case (b).

In the fourth case (d) in Fig. 6, a first vehicle comprising a CVT system 1 is driving behind a second vehicle 47, wherein the second vehicle 47 is an autonomous self-driving vehicle comprising one or more sensors 48 arranged to scan and assess a surrounding area of the vehicle 47. The one or more sensors 48 of the second vehicle 47 may provide a 360° view of the surrounding area, which may be used by the first vehicle 24 to obtain road condition information. While in this case the detector 38 of the first vehicle 24 has not reached the road irregularity 27 yet, the controller 5 of the first vehicle 24 may already receive relevant upcoming road condition information from the first vehicle 48. This illustrates inter- compatibility between different vehicles 24, 47 comprising different sensor systems 38, 48, respectively. Note that the second vehicle 47 may not comprise a CVT system 1. The communication between the vehicles may be achieved directly or indirectly, for instance by utilizing a cloud.

In the fifth case (e) in Fig. 6, a vehicle 24 is shown comprising a CVT system 1, wherein the controller 5 is arranged for retrieving information

representative of an upcoming road condition. The controller 5 (not shown) is arranged for, on the basis of the retrieved road condition information, adjusting the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17 in the variator 2 of the CVT system 1. In this example, information regarding the road irregularity 27 with respect to the vehicle 24, may be retrieved using local memory, cloud information and/or road condition information retrieved from other vehicles or arrangements. For example, a GPS sensor may be used to determine the location and speed of the vehicle 24, by which, if provided with upcoming road condition information the controller can adjust the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17 when deemed necessary. For instance, in this example, detailed upcoming road condition information may be available in a memory in the vehicle 24, or be downloaded from a server, and the controller 5 can retrieve the upcoming road condition information. Furthermore, the controller 5 can link the upcoming road condition information with the location and speed of the vehicle in order to predict whether one or more of the wheels will encounter the road irregularity 27.

Fig. 7 shows a schematic diagram of a control strategy for a CVT system. Certain ambient conditions 20 for a vehicle comprising a CVT system 1 may be useful for the operation and control of the CVT system 1. For example, a surface of a road or ground on which a vehicle is travelling or is going to travel can be relevant for the control of the CVT system 1. Therefore, the control strategy for the CVT system 1 will try to acquire the road condition information as predictive information by using an, e.g. optical, input device such as a camera as a detector, and or information made available by wireless communication with a cloud.

Advantageously, the optical input device may be positioned at a front of the vehicle so as to provide at least a forward scanning area for the vehicle. Furthermore, also reactive information can be obtained from other sensors such as a wheel speed sensor, tyre pressure sensor, artificial horizon sensor and/or steering angle sensor, utilized to enhance the road condition information. The acquired road condition information from the sensors and/or the cloud is then sent to the controller or TCU 5 of the CVT system 1.

According to the embodiment of Fig. 7 the controller 5 comprises two units, namely a clamping force calculation unit 22 arranged to determine and/or calculate the clamping force and a pressure setting unit 23 which is arranged for generating the pressure setting commands. The controller 5 receives road condition information and can predict torque peaks based on the information representative of the road condition. The hydraulic system is arranged to control friction members based on the pressure setting commands coming from the controller 5. In this way, the hydraulic system 6 will adjust the hydraulic pressure and/or the clamping force of the at least one friction element 15, 16 onto the torque transmitting member 17 in function of the predicted torque. In this example, control of the first friction element 15 may target clamping torque of the primary part of the variator while control of the second friction element 16 may target the clamping torque of the second part of the variator. The hydraulic system 6 may further be arranged to control other components of the CVT system 1.

During contact of the wheels with a road irregularity or object on the road, all kind of signals can be measured. For example, the event can be measured by use of severity estimation sensors, such as internal speed sensors, tyre pressure sensors, steering wheel angle sensors, artificial horizon sensor, wheel speed sensors, accelerometers and/or throttle pedal demand sensors. Pattern recognition can be performed to identify roads or road bumps. Other characteristics may be used, such as the fact that the location of the feet of the driver of the vehicle can vary shortly due to the vehicle movements. Based on this information a more accurate determination of the road condition can be performed. Said measurements can be used to improve the quality of the information on the road available in the cloud by sending the information or a summary of this information to the cloud.

The required clamping force or pressure in the variator 2 can be calculated based on corrected general road condition, wherein the road condition signals can be linked with a certain required clamping force or pressure level. This can be calibrated for each type of vehicle 24 during design and development of the CVT system 1. The severity of the impact, the effect on the wheels, object classification, the required clamping force or pressure level, etc. can be based on calibrations, tests, powertrain models, and/or training (e.g. artificial intelligence). Powertrain models can predict the torque fluctuations at the driven shafts, and thus the required clamping force or pressure levels.

In an embodiment, a general road condition estimation is obtained by use of a camera. It is possible that the general road condition, e.g. approximately 20 meters around vehicle, may comprise relevant features, such as a bad pavement, which are detected by use of the camera, but not registered by the other sensors (cfr. internal speed sensors, tyre pressure sensor, steering wheel speed angle sensor, accelerometer and throttle pedal demand sensor). In this case the expected/predicted road condition information may not fully correspond with the effects on the vehicle, so that the camera input can be corrected by the measured estimation by the other sensors, depending on the reliability of the actual inputs.

Weather information may be useful for the required clamping force or pressure in the variator 2 of the CVT system 1. Road type classifications coming from the cloud can be remapped to the classification used in this invention (e.g. IRI index, pavement, etc.). Available information on road objects, like potholes, kerbs, etc. and their properties can be used by the controller 5 to predict possible impact. GPS location can be used to determine exact location of the vehicle. GPS location of the vehicle can also be used to calibrate, and e.g. update in storage such as the cloud, known locations of road irregularities. Road condition information from previous vehicles can be made available to the vehicle 24. The required clamping force or pressure in the variator 2 depending on a location can be made available based on previous passes of the same vehicle or other vehicles able to communicate this information with the vehicle 24 comprising the CVT system 1.

Fig. 8 shows a flow chart of a method according to the invention. The method can be used for operating the CVT system 1 for a vehicle 24, comprising the variator 2 with the first friction element 15 and the second friction element 16 coupled through the torque transmitting member 17. The method comprises a step of setting a clamping force or pressure of at least one friction element 15, 16 onto the torque transmitting member. The clamping force or pressure can be optimally or advantageously be chosen in such a way that a reserve or safety margin, which may have a detrimental effect on the efficiency of the CVT system, can be avoided or reduced. The method can further comprise a step of retrieving information representative of an upcoming road condition, and a step of adjusting, on the basis of the retrieved information, the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17. The method for operating a continuously variable transmission system for a vehicle can at least partly be performed using dedicated hardware structures, such as ASIC and/or FPGA components. Otherwise, the method can also at least partially be performed using a computer program product comprising instructions for causing a processor of the computer system to perform the above described steps of the method according to the invention. Processing steps can in principle be performed on a single processor, in particular steps of retrieving upcoming road condition information. However, it is noted that at least one step can be performed on a separate processor.

The controller 5 may be arranged to receive current traffic situation in the environment of the vehicle, which can be at least partially information representative of an upcoming road condition. The traffic situation information may be a general measure, such as for example light traffic, medium traffic and heavy traffic. However, the traffic situation information may also include more detailed or specific data, such as positions and velocities of other road users (e.g. cars, cyclists, pedestrians, etc.), state of traffic lights and/or other features which could have an influence on the traffic. The controller 5 can be arranged to adjust the clamping force or pressure of the at least one friction element 15, 16 onto the torque transmitting member 17 on the basis of the retrieved traffic situation information in combination, possibly together with other retrieved road condition information. It is also possible that the traffic situation information is at least partially based on a traffic prediction by a computer model. Furthermore, the controller 5 may be arranged to retrieve said traffic situation information wirelessly from a network or cloud, an internal system in the vehicle and/or an external device (e.g. smartphone).

Herein, the invention is described with reference to specific examples of embodiments of the invention. It will, however, be evident that various

modifications and changes may be made therein, without departing from the essence of the invention. For the purpose of clarity and a concise description, features are described herein as part of the same or separate examples or embodiments, however, alternative embodiments having combinations of all or some of the features described in these separate embodiments are also envisaged.

The CVT system 1 may be implemented in or may take the form of a vehicle 24. Alternatively, the CVT system 1 may be implemented in or take the form of other vehicles, such as cars, recreational vehicles, trucks, buses,

motorscooter, bicycles, motorcycles, scooter, lawn mowers, agricultural vehicles, construction vehicles, golf carts, trolleys and robotic vehicles. Other vehicles are possible as well. The shown embodiments involved vehicles comprising four wheels, however vehicles with a different number of wheels can be utilized, such as but not limited to trikes, three-wheeled vehicles, squads, motorcycles, trucks vehicles including trailers etc.. Furthermore, the CVT system 1 can be employed in vehicles coupled to a trailer, semi-trailer, lorry, etc., wherein optionally the wheels of the trailer and/or semi-trailer can be considered as additional wheels of the vehicle by the CVT system 1. The CVT system 1 can be arranged to take into account wheels of other coupled vehicles in a similar fashion as the wheels of the vehicle

comprising the CVT system 1. It is also perceivable that a plurality of CVT systems 1 are included in a vehicle.

Fig. 9 shows a schematic diagram of an example of a control strategy for a CVT system 1. The road condition can be monitored using a camera and a cloud retrieving information representative of the road condition information.

Additionally, also other sensors can be employed so as to obtain a better prediction of the road condition information and/or to improve available road condition information for example available in a memory and/or a cloud. In the controller or TCU 5, a distinction is made between a general road condition and local road condition. Information representative for the road condition obtained using the camera and/or the cloud can be used by the TCU 5 so as to obtain both local road condition information and general road condition information. Information retrieved by other sensors can be used by the TCU 5 so as to build a general road condition information. On the basis of the retrieved general and local road condition information, the TCU 5 is arranged for adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member 17. From the obtained general road condition, the severity of impact can be estimated or determined by the TCU 5. The severity of impact can also be estimated or determined by the TCU 5 by employing the obtained local road condition information. However, said local road condition information can be used to predict time of impact. The severity of impact and time of impact enables the TCU 5 to perform a clamping torque calculation, wherein the result of the calculation or estimation can be used to set a clamping pressure (i.e. pressure setting) of at least one friction element 15, 16 onto the torque transmitting member 17. The pressure setting is used to control the hydraulic actuation system 6 of the CVT system 1, wherein the hydraulic actuation system 6 has a first hydraulic pressure line 7 which is connected to the first friction element 15 and a second hydraulic pressure line 8 which is connected to the second friction element 16. The hydraulic pressure in the first hydraulic pressure line 7 results in a first clamping force on a first friction element of the variator 2, and the hydraulic pressure in the second hydraulic pressure line 8 results in a second clamping force on a second friction element of the variator 2.

In the shown embodiments, the clamping force is delivered by a hydraulic actuation system 6. However other embodiments may include actuation by means of mechanical, electromechanical or electro-hydraulic systems.

The motor or engine 11 of the vehicle 24 comprising the CVT system 1 according the current invention may be or include any combination of an internal combustion engine and an electric motor. Other motors and engines are possible as well such as a fuel-cell motor. In some embodiments, the motor 11 could include multiple types of engines and/or motors. For instance, a gas-electric hybrid car could include a gasoline engine and an electric motor. Other examples are possible.

With regard to the torque transmitting member, a number embodiments are disclosed herein comprising a pushbelt type variator. However, different types of belts for CVTs are known, such as dry belts, chain belts and push belts, which can be used for the invention according to the current application. Also other types of CVT systems, for which the torque is transmitted based on friction elements being controlled by one or more clamping forces are disclosed herein, which can be toroidal type CVT's, Ratcheting CVT's, Cone CVT's or others. It will be appreciated that the method may include computer

implemented steps. All above mentioned steps can be computer implemented steps. Embodiments may comprise computer apparatus, wherein processes performed in computer apparatus. The invention also extends to computer programs,

particularly computer programs on or in a carrier, adapted for putting the invention into practice. The program may be in the form of source or object code or in any other form suitable for use in the implementation of the processes according to the invention. The carrier may be any entity or device capable of carrying the program. For example, the carrier may comprise a storage medium, such as a ROM, for example a CD ROM or a semiconductor ROM, or a magnetic recording medium, for example a floppy disc or hard disk. Further, the carrier may be a transmissible carrier such as an electrical or optical signal which may be conveyed via electrical or optical cable or by radio or other means, e.g. via the internet or cloud.

Some embodiments may be implemented, for example, using a machine or tangible computer-readable medium or article which may store an instruction or a set of instructions that, if executed by a machine, may cause the machine to perform a method and/or operations in accordance with the embodiments. Such a machine may include, for example, any suitable processing platform, computing platform, computing device, processing device, computing system, processing system, computer, processor, or the like, and may be implemented using any suitable combination of hardware and/or software. The machine-readable medium or article may include, for example, any suitable type of memory unit, memory device, memory article, memory medium, storage device, storage article, storage medium and/or storage unit, for example, memory, removable or non-removable media, erasable or non-erasable media, writeable or re-writeable media, digital or analog media, hard disk drive, floppy disk, Compact Disk Read Only Memory (CD- ROM), Compact Disk Recordable (CD-R), Compact Disk Rewriteable (CD-RW), optical disk, magnetic media, magneto-optical media, removable memory cards or disks, various types of Digital Versatile Disk (DVD), a tape, a cassette, or the like. The instructions may include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, encrypted code, and the like, implemented using any suitable high-level, low-level, object-oriented, visual, compiled and/or interpreted programming language.

Various embodiments may be implemented using hardware elements, software elements, or a combination of both. Examples of hardware elements may include processors, microprocessors, circuits, application specific integrated circuits (ASIC), programmable logic devices (PLD), digital signal processors (DSP), field programmable gate array (FPGA), logic gates, registers, semiconductor device, microchips, chip sets, et cetera. Examples of software may include software components, programs, applications, computer programs, application programs, system programs, machine programs, operating system software, mobile apps, middleware, firmware, software modules, routines, subroutines, functions, computer implemented methods, procedures, software interfaces, application program interfaces (API), methods, instruction sets, computing code, computer code, et cetera.

The graphics and/or image/video processing techniques may be implemented in various hardware architectures. Graphics functionality may be integrated within a chipset. Alternatively, a discrete graphics processor may be used. For example, processing of images (still or video) may be performed by a graphics subsystem such as a graphics processing unit (GPU) or a visual processing unit (VPU). As still another embodiment, the graphics or image/video processing functions may be implemented by a general purpose processor, including e.g. a multi-core processor. In a further embodiment, the functions may be implemented in a consumer electronics device. Embodiments, using a combination of different hardware architectures are possible.

In various embodiments, the controller can communicate using wireless systems, wired systems, or a combination of both. When implemented as a wired system, the system may include components and interfaces suitable for

communicating or wired communications media, such as input/output (I/O) adapters, physical connectors to connect the I/O adapter with a corresponding wired communications medium. When implemented as a wireless system, the system may include components and interfaces suitable for communicating over a wireless shared media, such as one or more antennas, transmitters, receivers, transceivers, amplifiers, filters, control logic, and so forth. An example of wireless shared media may include portions of a wireless spectrum, such as the RF spectrum and so forth. A wireless communication device may be included in order to transmit and receive signals using various suitable wireless communications techniques. Such techniques may involve communications across one or more wireless networks. Exemplary wireless networks include, but are not limited to, cellular networks, wireless local area networks (WLANs, cfr. WiFi), wireless personal area networks (WPANs), wireless metropolitan area network (WMANs), satellite networks, et cetera. In communicating across such networks, the transmitter may operate in accordance with one or more applicable standards in any version.

modifications, variations, alternatives and changes may be made therein, without departing from the essence of the invention. For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, alternative embodiments having combinations of all or some of the features described in these separate embodiments are also envisaged and understood to fall within the framework of the invention as outlined by the claims. The specifications, figures and examples are, accordingly, to be regarded in an illustrative sense rather than in a restrictive sense. The invention is intended to embrace all alternatives, modifications and variations which fall within the spirit and scope of the appended claims. Further, many of the elements that are described are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word 'comprising' does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words 'a' and 'an' shall not be construed as limited to 'only one', but instead are used to mean 'at least one', and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to an advantage.

Claims

1. Continuously variable transmission system for a vehicle, comprising:

a variator having two friction elements, wherein a first friction element is coupled to a second friction element through a torque transmitting member, a clamping force or pressure of at least one friction element onto the torque transmitting member being adjustable;

a controller arranged for retrieving information representative of an upcoming road condition

wherein the controller is arranged for, on the basis of the retrieved information, adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member.

2. Continuously variable transmission system according to claim 1, wherein the controller is arranged for predicting a change in the variator input and/or output torque on the basis of the retrieved information, and adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member according to the predicted torque change.

3. Continuously variable transmission system according to claim 1 or 2, wherein the controller is arranged for predicting a moment on which the variator input and/or output torque will change on the basis of the retrieved information, and adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member according to the predicted torque change.

4. Continuously variable transmission system according to claim 2 or 3, wherein the controller is arranged for adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member if the predicted change in the variator input and/or output torque exceeds a

predetermined threshold level.

5. Continuously variable transmission system according to any one of the preceding claims, wherein the controller is arranged for retrieving information representative of the road condition from a detector for detecting a road condition.

6. Continuously variable transmission system according to any one of the preceding claims, wherein the detector is arranged for determining the road condition in front of the vehicle.

7. Continuously variable transmission system according to any one of the preceding claims, wherein the detector is placed in the vehicle.

8. Continuously variable transmission system according to any one of the preceding claims, wherein the controller is arranged for being wirelessly communicatively connected to the detector.

9. Continuously variable transmission system according to claim 8, wherein the controller is arranged for communicating with the detector, the detector being placed in a further vehicle, preferably driving in front of the vehicle including the continuously variable transmission system.

10. Continuously variable transmission system according to claim 8 or 9, wherein the controller is arranged for communicating with the detector, the detector being placed stationary relative to the road.

11. Continuously variable transmission system according to any one of the preceding claims, wherein the controller is arranged for communicating with a network for retrieving the road condition information.

12. Continuously variable transmission system according to claim 11, wherein the network includes a memory storing the road condition information.

13. Continuously variable transmission system according to claim 11 or 12, wherein the network communicates with one or more detectors arranged for determining the road condition, the one or more detectors being placed stationary relative to the road and/or in vehicles.

14. Continuously variable transmission system according to claim 11, 12 or 13, further including a network server arranged for providing the road condition information to the controller.

15. Continuously variable transmission system according to claim 14, wherein the network server is arranged for receiving from the controller an indication of a location of the controller, and for transmitting to the controller road condition information relating to the location of the controller.

16. Continuously variable transmission system according to any one of the preceding claims, wherein the detector includes an optical system, such as a digital camera, a radar system, a lidar system, and/or an acoustic system.

17. Continuously variable transmission system according to claim 16, wherein the controller is arranged for analyzing an image provided by the camera, for features indicative of the road condition.

18. Continuously variable transmission system according to any one of the preceding claims, wherein the system further includes a wheel speed sensor, and the controller is arranged for adjusting the clamping force or pressure of the at least one friction element onto the member further on the basis of the detected wheel speed.

19. Continuously variable transmission system according to any one of the preceding claims, wherein the system further includes a tyre pressure sensor, and the controller arranged for adjusting the clamping force or pressure of the at least one friction element onto the member further on the basis of the detected tyre pressure.

20. Continuously variable transmission system according to any one of the preceding claims, wherein the system further includes an artificial horizon sensor, and the controller arranged for adjusting the clamping force or pressure of the at least one friction element onto the member further on the basis of the detected horizon.

21. Continuously variable transmission system according to any one of the preceding claims, wherein the system further includes a steering angle sensor, and the controller arranged for adjusting the clamping force or pressure of the at least one friction element onto the member further on the basis of the detected steering angle.

22. Continuously variable transmission system according to any one of the preceding claims, wherein the system is arranged to deliver variable output speeds and torques to one or more wheels coupled to the system, wherein the retrieved information representative of the road condition is employed to determine an estimated interaction of at least one of the one or more wheels with an upcoming road.

23. Continuously variable transmission system according to claim 22, wherein a plurality of wheels are coupled to the system for which an estimated interaction with an upcoming road is determined, wherein said estimated interaction is determined together or individually.

24. Continuously variable transmission system according to claim 22 or 23, wherein the controller is arranged such as to recognize when one or more additional wheels are coupled to the system, wherein the retrieved information representative of the road condition is further employed to determine an estimated interaction of at least one of the additional wheels with an upcoming road.

25. Vehicle comprising a continuously variable transmission according to any one of claims 1-24.

26. Vehicle according to claim 25 further comprising the detector.

27. Network server arranged for transmitting information representative of a road condition to a vehicle including a continuously variable transmission system according to any one of claims 1-24.

28. Network server according to claim 27, arranged for receiving information representative of a road condition from one or more sensors.

29. Network server according to claim 27 or 28 arranged for receiving information representative of a road condition and/or a clamping force or pressure from a vehicle.

30. Network server according to any one of claims 27-29, arranged for receiving from a vehicle an indication of a location of that vehicle, and for transmitting to the vehicle information representative of the road condition at and/or near a location of the vehicle.

31. Network server according to any one of claims 27-30, having associated therewith a memory storing information representative of road conditions.

32. Method for operating a continuously variable transmission system for a vehicle, including a variator with a first friction element and a second friction element coupled through a torque transmitting member, the method including:

setting an optimal clamping force or pressure of at least one friction element onto the torque transmitting member;

- retrieving information representative of an upcoming road condition;

on the basis of the retrieved information, adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member.

33. A computer program product for operating a continuously variable transmission system for a vehicle, including a variator with a first friction element and a second friction element coupled through a torque transmitting member, which computer program product comprises instructions for causing a processor to perform the steps of: providing a signal for setting an optimal clamping force or pressure of at least one friction element onto the torque transmitting member;

receiving information representative of an upcoming road condition; and providing a signal for adjusting the clamping force or pressure of the at least one friction element onto the torque transmitting member, based on the retrieved information.